# Hatari User's Manual

Version 1.5

Manual written by: Thomas Huth, Matthias Arndt & Eero Tamminen

Hatari on the WWW: http://hatari.berlios.de/

## Index

- Introduction
  - General description
  - Features
  - STE hardware emulation
  - Experimental TT hardware emulation
  - Falcon hardware emulation
  - System requirements
- Compiling and running
  - Compiling Hatari
  - Installation of a TOS ROM
  - Installation of the binary
  - Running Hatari for the first time
- Command line options and arguments
- Using the emulated system
  - The GUI
    - The Main Menu
    - The File Selector Dialog
    - The System Dialog
    - The Floppy Disks Dialog
    - The Hard Disks Dialog
    - The Memory Dialog
    - The ROM Dialog
    - The Joystick Dialog
    - The Atari Monitor Dialog
    - The Hatari Screen Dialog
    - The Keyboard Dialog
    - The Sound Dialog
    - The Devices Dialog
  - Keyboard shortcuts
  - Emulated Atari ST keyboard
  - Emulated mouse
  - Emulated joystick
  - Emulated video
  - Emulated printer
  - Emulated RS232
- Floppy disk images
- Hard disk support
  - GEMDOS based hard disk emulation
  - ACSI hard disk emulation
  - IDE hard disk emulation
- Moving files to/from hard disk images
  - Using HD Driver with GEMDOS partitions
  - Accessing HDD image partitions outside of Hatari
- The debugger
  - General debugger use
  - Inspecting emulation state
  - Debug symbols
  - Breakpoints
  - Tracing
  - Profiling
  - Usage examples
  - Build notes
- Performance
  - Improving Hatari performance
  - Emulation options
  - Emulator options
  - Measuring the performance
- Appendix
  - Copying
  - Introduction to Emulation

## Introduction

### General description

Hatari is an Atari ST, STE, TT and Falcon emulator for Linux, OSX, Windows and other Systems which are supported by the SDL library. The emulator is open source software and is distributed under the terms of the GNU General Public License (GPL).

The Atari ST was a 16/32 bit computer system which was first released by Atari in 1985. Using the Motorola 68000 CPU, it was a very popular computer having quite a lot of CPU power at that time. See Appendix B for details on emulation in general.

Unlike many other Atari ST emulators which try to give you a good environment for running GEM applications, Hatari tries to emulate the hardware of a ST as close as possible so that it is able to run most of the old ST games and demos. Of course you can run normal GEM applications with Hatari, too. Recent versions of Hatari even feature STE, Falcon and basic TT emulation.

### Features

- 68000 - 68040 emulation via the UAE CPU core (no PMMU support though)
- ST RAM size variable (from 512kiB up to 14MiB are possible)
- optional cartridge images for the ST ROM port
- most of the ST specific hardware
- ST Shifter with ST-High, ST-Medium and ST-Low resolutions, overscan effects for all borders in color resolutions
- 512 color ST palette
- Spec512 mode support for low and medium resolutions
- many raster effects
- scaling of low resolutions by factor two
- interleaved lines rendering of ST-medium and (scaled) ST-low resolutions for the TV "monitor type"
- Blitter chip emulation
- PSG YM2149 emulation (soundchip) including STFM samples
- Printer port emulation on hardware level (print to file)
- RS232 emulation
- MIDI input/output/through emulation
- Mega ST real time clock
- IKBD emulation (keyboard, mouse and joystick) with custom keyboard mapping
- joystick emulation via cursor keys and joystick emulation via a connected PC joystick
- FDC emulation using floppy disk images in standard formats (*.ST, *.MSA and *.DIM)
- support for packed disk images (PkZip and Gzip)
- optional write-protection for floppy disk images
- partial ACSI emulation for harddisk support
- GEMDOS interface driver to mount directories as harddrives with optional write-protection
- support for memory snapshots (save whole system state)
- driver for extended VDI resolutions
- recording of sound as .WAV and .YM files
- screenshots in PNG or BMP format
- AVI animation capturing with sound
- TOS versions 1.00, 1.02, 1.04 and 2.06 (and EmuTOS) can be used in ST mode.

#### STE hardware emulation

There is support for following additional STE features:

- horizontal and vertical hardware fine scrolling
- split screen techniques / in-screen video address manipulations
- (STE specific) left border opening
- 4096 colors STE palette
- Stereo DMA sample sound
- Experimental Microwire/LMC1992 emulation
- STE joypads
- TOS versions 1.06, 1.62, 2.05 and 2.06 (and EmuTOS) can be used in STE mode.

#### Experimental TT hardware emulation

There is support for following additional TT features:

- TT low/med/high resolution support
- ST/TT palette switching and video shifter
- RAM upto 14MiB (ST-RAM only, there is no support for TT-RAM yet)
- Only TOS version 3.06 (and EmuTOS) can be used in TT mode.

#### Falcon hardware emulation

There is support for following additional Falcon features:

- Partial Videl emulation for all Falcon screen modes
- Aspect correction and scaling of small resolutions by an integer factor
- STE/Falcon palette switching and shifter
- Mono/RGB/VGA/TV monitor types
- DSP co-processor emulation
- Experimental microphone (jack) emulation
- Experimental Crossbar sound matrix (ADC (mic & PSG), DAC, DMA, DSP) interconnect emulation + support for the additional DMA sound sample rates
- Experimental IDE master and slave emulation for harddisk support
- TOS versions 4.00, 4.02, 4.04 and 4.92 (and EmuTOS) can be used in Falcon mode.

See the developers' doc/todo.txt file (included with Hatari sources) for the details on the few remaining emulation gaps and the Hatari Atari Software Compatibility List for which Atari programs are known to be affected by them.

### System requirements

Hatari currently has the following minimum system requirements:

- a fast PC (>500MHz, for Falcon and TT emulation even faster)
- some sort of Unix (preferable GNU/Linux)
- the SDL library (http://www.libsdl.org/)
- the zLib (http://www.gzip.org/zlib/) for support of ZIP-packed disk images (*.zip and *.gz)

Earlier versions of Hatari have successfully been tested by various people on the following systems:

- Linux/i86 with Kernel 2.4.x and 2.6.x
- Linux/PPC with Kernel 2.4.x and 2.6.x
- BeOS/i86
- Apple Mac OS X on PowerPC and i86
- NetBSD 1.6
- NetBSD on a Digital Alpha
- FreeBSD 4.1 on an i486, FreeBSD 4.8 on a Pentium 4 and FreeBSD 5.1
- OpenBSD 3.5
- Solaris 8 on a SUN UltraSparc 1
- Linux/ARM (oabi) on Sharp Zaurus SL-C760 PDA
- Linux/ARM (eabi) on Nokia Maemo Internet Tablets and N900 phone

## Compiling and running

### Compiling Hatari

Required:

- A C compiler. Preferably GCC, but others have worked too.
- A working CMake installation. See http://www.cmake.org/ for details.
- The SDL library v1.2.10 or newer. You can get it from http://www.libsdl.org/.
- The zLib compression library. You can get it from http://www.gzip.org/zlib/.

Optional:

- The PNG image library for PNG format screenshots and to decrease AVI video recording file sizes. You can get it from http://www.libpng.org/.
- The GNU Readline library for Hatari debugger command line editing.
- The Xlib library to support Hatari Python UI window embedding on systems with the X window system (Linux and other unixes).
- The portaudio library for Falcon microphone recording support

The versions available in your Linux distribution will be sufficient in most cases, but make sure you have also the header files installed for the libraries as well! Typically they're in a corresponding -dev package.

After you've verified that you have the required libraries and their development files, change to the hatari/ directory. Create a build/ directory under it and configure the build system for your environment:

    mkdir -p build
    cd build
    cmake ..

Then compile Hatari by typing make. If all works fine, you'll get the executable hatari in the src/ subdirectory.

Note: Instead of calling CMake directly, you can also use the supplied configure script to run CMake and to give the arguments (like install prefix) in a format familiar from GNU Autotools using programs. Type "./configure --help" to see all the options supported by this script.

### Installation of a TOS ROM

Before you can start Hatari, you have to copy a TOS ROM image to the data directory (<prefix>/share/hatari/, by default /usr/local/share/hatari/) and rename it to tos.img, or use the --tos command line option to tell Hatari where to find a TOS ROM. Hatari needs a TOS ROM image because this contains the operating system of the emulated Atari.

Unfortunately it is not possible to ship an original ROM image with the Hatari package since these images are still copyrighted. But you can easily create an image with a real ST and one of those various ROM-image programs for the ST (search for "TOSDUMP" with your favourite internet search engine). If your old ST does not work anymore, you can also try to search the internet directly for corresponding TOS ROM image, but don't ask the Hatari team where to get one.

Another solution is EmuTOS, which is also shipped with the official release versions of Hatari. EmuTOS is an open-source TOS clone. You can find it at: http://emutos.sourceforge.net/. It is not the best solution for playing games or running other old software due to compatibility issues (see emutos.txt for more details), but it's free and compatible with Hatari.

If you do not specify a TOS image on the commandline nor can Hatari find a suitable TOS image in the default dir, you'll get the chance to select a TOS image file from the GUI.

### Installation of the binary

Type make install as "root" user to do a systemwide installation.

Assuming you didn't change the default installation prefix and that /usr/local/bin/ is in your PATH, you should be now able to start the Hatari executable from anywhere.

When you finally have got a TOS image, try starting Hatari with the option --help to find out more about its command line parameters.

### Running Hatari for the first time

Now type hatari to run the emulator for the first time. If all goes well, you should now be presented with a window showing you the familiar little green desktop of the Atari ST. Press F12 to turn on the GUI to configure Hatari to suit your needs, press F11 to toggle windowed and fullscreen mode.

## Command line options and arguments

Usage:

     hatari [options] [disk image | directory | Atari program ]

As an argument one can give either a name of:

- A floppy disk image,
- A directory that should be emulated as a virtual GEMDOS hard disk, or
- An Atari program that should be autostarted. In this case the program's directory will be used as the C: drive from where this program will be started. (Note that autostarting a program might not work if you've also specified a floppy image for drive A: on command line or in config file which contains a desktop.inf/newdesk.inf/emutos.inf file on it.)

Booting will be done from the disk image or directory that's given last on the command line as an option or the argument (and which corresponds to A: or C:).

Hatari command line options are split into several categories:

### General options

| -h, --help

| Print command line options and terminate

| -v, --version

| Print version information and terminate

| --confirm-quit <bool>

| Whether Hatari confirms quitting

| -c, --configfile <filename>

| use the given file as configuration file instead of ~/.hatari/hatari.cfg

| -k, --keymap <file>

| load keyboard mapping from <file>

### Common display options

| -m, --mono

| Start in monochrome mode instead of color

| --monitor <x>

| Select monitor type (x = mono/rgb/vga/tv)

| -f, --fullscreen

| Start the emulator in fullscreen mode

| -w, --window

| Start the emulator in window mode

| --grab

| Grab mouse (also) in window mode

| --fast-forward <bool>

| On fast machine helps skipping (fast forwarding) Hatari output

| --frameskips <x>

| Skip <x> frames after each displayed frame to accelerate emulation (0=disabled, >4 uses automatic frameskip with given value as maximum)

| --statusbar <bool>

| Show statusbar (with floppy leds etc etc)

| --drive-led <bool>

| Show overlay drive led when statusbar isn’t shown

| --bpp <bool>

| Force internal bitdepth (x = 8/15/16/32, 0=disable)

### ST/STE specific display options

| --borders <bool>

| Show screen borders (for low/med resolution overscan demos)

| --spec512 <x>

| Hatari uses this threshold to decide when to render a screen with the slower but more accurate Spectrum512 screen conversion functions (0 <= x <= 512, 0=disable)

| -z, --zoom <x>

| Zoom low resolution (1=no, 2=yes)

### Falcon/TT specific display options

Zooming to sizes specified below is internally done using integer scaling factors. This means that different Atari resolutions may show up with different sizes, but they are never blurry.

| --desktop <bool>

| Whether to use desktop resolution on fullscreen to avoid issues related to resolution switching. Otherwise fullscreen will use a resolution that is closest to the Hatari window size

| --max-width <x>

| Maximum window width for zooming

| --max-height <x>

| Maximum window height for zooming

| --aspect <bool>

| Whether to do monitor aspect ratio correction

### VDI options

| --vdi <bool>

| Whether to use VDI screen mode

| --vdi-planes <x>

| Use extended VDI resolution with bit depth <x> (x = 1, 2 or 4)

| --vdi-width <w>

| Use extended VDI resolution with width <w> (320 < w <= 1280)

| --vdi-height <h>

| Use extended VDI resolution with height <h> (200 < h <= 960)

### Screen capture options

| --crop <bool>

| Remove statusbar from the screen captures

| --avirecord

| Start AVI recording

| --avi-vcodec <x>

| Select avi video codec (x = bmp/png)

| --avi-fps <x>

| Force avi frame rate (x = 50/60/71/...)

| --avi-file <file>

| Use <file> to record avi

### Devices options

| -j, --joystick <port>

| Emulate joystick with cursor keys in given port (0-5)

| --joy<port> <type>

| Set joystick type (none/keys/real) for given port

| --printer <file>

| Enable printer support and write data to <file>

| --midi-in <filename>

| Enable MIDI support and write MIDI data to <file>

| --midi-out <filename>

| Enable MIDI support and read MIDI data from <file>

| --rs232-in <filename>

| Enable serial port support and use <file> as the input device

| --rs232-out <filename>

| Enable serial port support and use <file> as the output device

### Disk options

| --disk-a <file>

| Set disk image for floppy drive A

| --disk-b <file>

| Set disk image for floppy drive B

| --protect-floppy <x>

| Write protect floppy image contents (on/off/auto). With "auto" option write protection is according to the disk image file attributes.

| --protect-hd <x>

| Write protect harddrive <dir> contents (on/off/auto). With "auto" option the protection can be controlled by setting individual files attributes as it disables the file attribute modifications for the GEMDOS hard disk emulation.

| -d, --harddrive <dir>

| Emulate harddrive partition(s) with <dir> contents

| --acsi <file>

| Emulate an ACSI hard disk with an image <file>

| --ide-master <file>

| Emulate an IDE master hard disk with an image <file>

| --ide-slave <file>

| Emulate an IDE slave hard disk with an image <file>

| --slowfdc <bool>

| slow down FDC emulation (deprecated)

### Memory options

| -s, --memsize <x>

| Set amount of emulated RAM, x = 1 to 14 MiB, or 0 for 512 KiB

| -t, --tos <imagefile>

| Specify TOS ROM image to use

| --cartridge <imagefile>

| Use ROM cartridge image <file> (only works if GEMDOS HD emulation and extended VDI resolution are disabled)

| --memstate <file>

| Load memory snap-shot <file>

### CPU options

| --cpulevel <x>

| Specify CPU (680x0) to use (use x >= 1 with EmuTOS or TOS >= 2.06 only!)

| --cpuclock <x>

| Set the CPU clock (8, 16 or 32 Mhz)

| --compatible <bool>

| Use a more compatible but slower 68000 CPU mode

### Misc system options

| --machine <x>

| Select machine type (x = st, ste, tt or falcon)

| --blitter <bool>

| Enable blitter emulation (ST only)

| --dsp <x>

| Falcon DSP emulation (x = none, dummy or emu, Falcon only)

| --mic <bool>

| Enable/disable (Falcon only) microphone

| --sound <x>

| Sound frequency: 6000-50066. "off" disables the sound and speeds up the emulation. To prevent extra sound artifacts, the frequency should be selected so that it either matches evenly with the STE/TT/Falcon sound DMA (6258, 12517, 250033, 50066 Hz) or your sound card frequencies (11025, 22050, 44100 or 6000...48000 Hz). Check what your sound card supports.

| --sound-buffer-size <x>

| SDL's sound buffer size : 10-100, or 0 to use default buffer size. By default Hatari uses an SDL buffer size of 1024 samples, which gives approximatively 20-30 ms of sound depending on the chosen sound frequency. Under some OS or with not fully supported sound card, this default setting can cause a bigger delay at lower frequency (nearly 0.5 sec). In that case, you can use this option to force the size of the sound buffer to a fixed number of milliseconds of sound (using 20 is often a good choice if you have such problems). Most users will not need this option.

| --ym-mixing <x>

| Select a method for mixing the three YM2149 voice volumes together. "table" uses a lookup table of audio output voltage values measured on STF and "linear" just averages the 3 YM voices.

| --timer-d <bool>

| Patch redundantly high Timer-D frequency set by TOS. This about doubles Hatari speed (for ST/e emulation) as the original Timer-D frequency causes most of the interrupts.

| --rtc <bool>

| Enable real-time clock

### Debug options

| -D, --debug

| Toggle whether CPU exceptions invoke the debugger

| --bios-intercept

| Toggle Bios/XBios call interception and BIOS CON: output (e.g. EmuTOS console) redidirection to host terminal. Needed for Bios/XBios call tracing. Allows Atari programs to modify Hatari state through XBios 255 calls.

| --trace <trace1,...>

| Activate debug traces, see --trace help for available tracing options

| --trace-file <file>

| Save trace output to <file> (default=stderr)

| --parse <file>

| Parse/execute debugger commands from <file>

| --control-socket <file>

| Hatari reads options from given socket at run-time

| --log-file <file>

| Save log output to <file> (default=stderr)

| --log-level <x>

| Log output level (x=debug/todo/info/warn/error/fatal)

| --alert-level <x>

| Show dialog for log messages above given level

| --run-vbls <x>

| Exit after X VBLs

Type hatari --help to list all the command line options supported by a given version of Hatari.

## Using the emulated system

Once you've started Hatari succesfully, you can use the emulator as an almost complete Atari ST computer system.

### The GUI

Press F12 to enter the GUI. Navigate it with the mouse. The GUI is rather self explanatory.

#### The Main Menu

You can reach the other setup dialogs from the main menu by clicking on the appropriate buttons.

You can load the current settings from a configuration file by clicking on Load config. and you can save the current settings to a configuration file by clicking on Save config..

Click OK to go back and continue the emulation. All changed options will be applied.

Select the Reset machine option if you want the emulated machine to perform a cold reset. This is equal to switching the power off and on again on a real Atari machine.

Click Quit to terminate Hatari and return to the host OS.

Click Cancel to abandon any changes that you have made.

#### The File Selector Dialog

The file selector dialog appears whenever you are prompted to choose a file or folder.

To enter a folder or choose a file, simply click on the entry in the main box of the dialog. You can use the arrows at the right, the cursor up and down keys and the page up and down keys to navigate through the list.

You can use the three buttons in the upper right corner for additional folder navigation. Use the .. button to go up one level in the directory tree. Use the ~ button to return to your home directory. The / button can be used to go to the root directory of the file system.

#### The System Dialog

First you can select the CPU type here. Here are some important hints for choosing the correct CPU type:

- Atari ST and STE have only been shipped with a 68000 CPU, so for best compatibility with old programs, choose this CPU type.
- Atari TT and Falcon computers were using the 68030 CPU, so you should switch use 68EC030+FPU (Hatari doesn't support 030 with MMU and some programs don't work with 68020 so this is the best choice).
- TOS 1.0x only works with 68000, while TOS 3.0x and 4.0x work only with a CPU >= 68020.
- 68010 and 68040 have never been used in official Atari computers, so don't use these CPU types unless you've got some good reasons.

Beside the CPU type, you can also choose the machine type to emulate. The ST was the very first 16/32-bit computer from Atari. Most older games and demos require an ST. The STE was introduced some years later and had some more advanced hardware features. There are not that many demos or games that really require an STE but since most normal ST games/demos also work with an STE, it's normally safe to always work in STE mode.
TT and Falcon are more advanced, but they are not as compatible to the ST as the STE was. Therefore many old games and demos do not work with these machine types anymore. There were only very few programs that were made for the TT exclusively, while there were some interesting games and demos specially made for the Falcon. Note: TT and Falcon emulation are incomplete. They may not work very well.

For STE emulation a STE compatible TOS image, e.q. version 1.06, 1.62 or 2.x, is strongly recommended. For TT emulation you need TOS 3.0x and for Falcon emulation you need TOS 4.0x. EmuTOS can be used on all machine types.

Select the CPU clock you want to use. 8Mhz is ST standard and the most compatible. Use 16MHz for Mega STE and Falcon emulation. The CPU in the TT was clocked with 32 MHz.

With the "Slower but more compatible CPU" option, you can enable the emulation of 68k address errors and the CPU prefetch buffer. This is needed for best compatibility, but it slows down emulation a little bit so you can disable it if you don't need it.

For Falcon mode, you can choose whether you want to enable DSP emulation, fake it or completely disable it. Most Falcon programs only play sound or work correctly when you enable the DSP emulation, but it needs a lot of host CPU power (more than 2 GHz). So if you have a slow host CPU, you can try if your Falcon program also runs with DSP disabled or in "dummy" mode. Note that you can not change this option while the DSP based program already runs.

You can also enable/disable Blitter emulation here. The Blitter is a custom chip that accelerates some graphical operations. This switch only toggles the Blitter in plain ST mode. In STE mode, the Blitter is always enabled (since all STEs have been sold with a Blitter chip).

If you enable the "Real time clock emulation" switch, a RTC will be emulated based on the time of the host computer. Note that you need at least TOS 1.02 for proper RTC emulation, TOS 1.00 does not support this.

The Timer-D patch changes the Timer-D initialization from TOS. TOS uses the MFP timer D as a baudrate generator for RS232. However, the TOS default value slows down the emulation. The patch gives you a better performance. It is normally safe to enable the patch, but if you encounter a program that does not work, you can try to disable the patch to see if it works then.

NOTE: The emulated Atari is very very sensitive to these options and it is strongly recommended to reset the emulation after changing them (for most things that's done automatically). The correct CPU type and clock are automatically selected when one uses the --machine command line option.

#### The Floppy Disks Dialog

This dialog can be used to choose which floppy disks should be emulated in the disk drives. You can use most standard Atari ST disk image files. You may select and browse also zipped disk images. See the chapter "Floppy disk images" for details.

Click on the button Browse next to the A: and B: option to go to the fileselector to choose a disk image for the corresponding drive.

Click on Eject to eject a disk image from the emulated drive. The emulated ST will act as if had no floppy disk in its drive.

You can specify a default directory where Hatari will start to browse the filesystem.

Check the "Auto insert B" option if you want Hatari to be smart and insert the second disk of a two disk game automatically. Some games then use the second drive automatically. In the case that a game is not able to find the disk in the second drive, you have to insert the second disk in drive A: manually when prompted.
NOTE: This option only works properly if the file name of the first disks ends with an 'a' before the extension and the second disk name ends with a 'b'.

Select if you want to use slow FDC (Floppy Disk Controller) emulation. "Slow floppy access" is normally not required, except for some few slideshows / intros which run too fast without this option.

You can choose if you want Hatari to write-protect your disks. Atari ST virii can spread on disk images too so it might be a good idea to enable the write protection option. However you can't save highscores or games to your disk images in that case.

If you need to create a new blank disk image, click on Create blank image. Parameters for the new image can be set in the following dialog. HD and ED disk sector counts are for non-Atari disk sizes, but such disks are useful for programs that don't work with GEMDOS emulation. Click on Create to save the new image or on Back to return to the disk dialog.

After clicking Create, a fileselector appears. You can browse the filesystem now. Select the target directory, click beside "File:" and type in a name for the new disk image. The name should terminate with .st or .msa.

Hatari can currently create plain .ST and .MSA disk images exclusively. hmsa command line utility can be used to convert disk images between .ST and .MSA formats.

#### The Hard Disks Dialog

This dialog can be used to change the harddisk settings.

You can select a harddrive image for ACSI, IDE master or slave hard drive emulation via image file here or you may select a directory of your local filesystem to be emulated as the harddrive of the emulated system.

Check "Boot from HD" if you want Hatari to execute the AUTO folder on the harddrive. This option is checked by default if you specify a harddrive image or a directory via the command line.

Removing the check from the "Allow GEMDOS drive modification" option will prevent Atari programs from modifying the files in GEMDOS HDD emulation directory or creating new files under it.

Note that for IDE hard disk emulation you also need a TOS version >= 2.05. And ACSI hard disk emulation does not work with TOS 4.0x in Falcon mode.

#### The Memory Dialog

You can select the amount of RAM for the emulated ST here. Only amounts that were valid on a real unmodified STFM can be selected.

Note: This option is critical and you are strongly advised to reset the emulated ST when changing this option.

Here you will find the options to save memory snapshots as well.

Click on Save to save a memory snapshot to file. You can select a new filename here.

Click on Restore to restore a memory snapshot from a file. Use the fileselector to select the snapshot to be restored.

NOTE: Memory snapshots are not interchangeable between different versions of Hatari. E.q. if you compile a newer Hatari, you cannot load your old memory snapshots back.

#### The ROM Dialog

Here you can select the TOS image to use. Click on Browse to select it via the fileselector. You can also select an optional cartridge image to use. Click on Browse to select one via the fileselector. Click on Eject to disconnect the custom cartridge image.

For ST mode, use TOS 1.00, 1.02, 1.04 or 2.06. For STE mode, use TOS 1.06, 1.62, 2.05 or 2.06. If you want to use the TT mode, you must specify a TOS 3.06 image here. And in Falcon mode, you have to use either TOS 4.00, 4.02, 4.04 or 4.92. However, you should always use TOS 4.04 for Falcon mode, it's the most common one. Also note that TOS 4.92 can not be booted from a boot disk (like it's done on a real Falcon), you have to specify it directly in the TOS ROM setup dialog here.

Keep in mind that any custom cartridge image will not work together with GEMDOS hard disk emulation or the VDI extended resolution emulation since some additional driver code will be used in the cartridge memory space for these emulations.

Note: These options are critical and you are strongly advised to reset the emulated ST when changing one of these option.

#### The Joystick Dialog

In this dialog, you can configure the emulated joysticks. With the upper two arrows, you can choose the joystick which you want to configure.

Joystick 1 is the normal ST joystick port and 99.9% of all ST games use this port. Joystick 0 emulates a joystick plugged into the ST mouse port and is often used in games for two players.

With STE joypad A and B, you can enable the emulation of Jaguar joypads which are plugged in the enhanced joystick ports of the Atari STE. Only very few STE games support these joypads, so you often won't need this.

Finally, Hatari also emulates joysticks which were plugged on the parallel port with a special adapter on a real ST. These were used in some few multi-player games like "Gauntlet 2".

For each ST joystick, choose whether you want to disable it, use the keyboard for emulation or use a real PC joystick.

For keyboard emulation, you can select the keys by pressing the Define keys button. You will be prompted to press the keys for up, down, left, right and fire.

If you want to use a real PC joystick for the emulation, you should connect it to your PC before you start Hatari. Then you can choose the joystick with the two lower arrows.

Check the "Enable autofire" option if you are too lazy to pound on the fire button in shoot'em-up games. However, this option only works with certain games. In some other games, it gets worse if you enable this option.

See also the chapter "Emulated Joystick" for details.

#### The Atari Monitor Dialog

Here you control the video output of the emulated Atari.

You can select which sort of monitor to use. This option depends on the machine type which you have selected in the "System options" dialog. In ST and STE mode, you can choose between monochrome mode (select "Mono") and color mode (select one of the other monitor types). Note that when you select "TV" and use zoomed low resolution or switch to ST medium resolution, you will get a TV-like screen rendering which is a little bit faster but darker compared to the normal "RGB" monitor mode. Switching between mono and a color monitor acts like a monitor switch on a real ST - so beware, this will reboot your emulated system!
In TT mode, you can only choose between TT-high resolution ("Mono") and normal modes (select one of the other monitor types). Finally the Falcon mode supports all four types of monitors. Note that most Falcon demos/games require a RGB or TV mode and do not work with VGA.

"Show ST/STE borders" toggles the displaying of the borders around the ST / STE screen. Some demos and games use the screen borders for displaying additional graphics. As enabling this option increases CPU computing time, don't enable it if you have a very slow computer. This option affects only the ST and STE modes, TT and Falcon modes are always displayed without borders.

Extended VDI resolutions will emulate a sort of extended graphics card in the emulated ST which give you larger resolutions with a higher colordepth for GEM. Select a resolution and color depth. Check to activate. It will disable all other video options mentioned above. Uncheck to get back to a normal ST behaviour.
Note: Using an extended resolution will only work with GEM conformant applications. 99% of all games and demos will not run if you activate any extended resolution here.

#### The Hatari Screen Dialog

Here you control how the video output of the emulated Atari appears on your screen.

Check "Fullscreen" to run Hatari in fullscreen. By default Hatari runs in windowed mode.

The "Frame Skip" option can be used to speed up the emulator if it is running too slow on your system. Disable frame-skip if you have a fast computer. When selecting 1, 2 or 4, drawing of corresponding number of frames will be skipped after each frame actually shown by Hatari. Select "Auto" to let the emulator to decide whether, and how many frames will be skipped.
Note: The frameskip option also affects the frame rate of the screen animation recording!

Indicators that you can have on the Hatari window:

- "Statusbar" at the bottom of the screen. The statusbar shows the floppy drive LEDs, the current frameskip value, the machine type including TOS version and memory size, and whether recording is currently active.
- "Drive led" is a colored rectangle shown on top of the Hatari window contents. It will show any disk (floppy or hard disk) activity.
- "None" turns both of above options off.

"Keep desktop resolution" option will use your desktop resolution for fullscreen to avoid issues related to resolution switching, especially on LCD monitors (they're slow). If this isn't enabled, values from the "Max zoomed win" option are used in selecting a suitable resolution.

"Max zoomed win" option controls up to which size Hatari tries to scale the Atari resolutions and how much of the borders (enabled in Atari Monitor dialog) will be shown. Note that there are several limitations in this and the "Keep desktop resolution" option, partly because Hatari has different implementations for different video modes:

- VDI resolutions (selectable in Atari Monitor dialog) aren't scaled.
- ST and STE video emulation supports only doubling of the ST-low resolution.
- Hatari doesn't support downscaling. If the original Atari resolution is larger than the specified size (e.g. TT-high), the Hatari screen size will also be larger than requested. Hatari Falcon/TT window size will be limited to the Desktop size though.
- TT and Falcon resolutions support only integer scaling ratios. If the scaling ratio cannot match the requested size exactly, Hatari will use a ratio that will produce smaller size closest to the requested one.

You should set these values to a size that suits best your monitor resolution. It's intended to help in getting Hatari to best use your monitor space on a windowed mode and in fullscreen avoiding "fuzzy" scaling done by your LCD monitor.

Giving "-z 2" option on command line will reset max zoomed size to default values and "-z 1" will disable all zooming. Note that zooming takes additional CPU computing time and should not be enabled on very slow computers.

Click the Screenshot button to create a screenshot in PNG (or BMP) format to the current working directory or click the Record AVI button to record an AVI format video of Hatari screen (and audio) output.

Selecting "Crop statusbar" option will leave statusbar out from the screenshots and recorded videos.

#### The Keyboard Dialog

Here you can select the keyboard mapping to use. Two different mappings called "Symbolic" and "Scancode" are predefined.

"Symbolic" tries to map the symbolic values of your PC keys to the ST keys. It should be working pretty good on all systems as long as your keyboard layout looks close to the standard english keyboard layout. However, you might experience some problems with special keys like brackets etc.

"Scancode" uses the scancode values of your PC keys for keyboard mapping. This only works on certain architectures like Linux where the scancodes are similar to the ST scancodes (e.g. it does not work on Mac OS X). If it works on your system, this often gives better results than the symbolic mapping. Note that you also need a TOS version with the right language (e.g. use a French TOS if you are using a French keyboard).

You can also load a custom keyboard mapping file here if you wish. Please note that the custom keyboard mapping will use the "symbolic" mapping for all keys that are not defined by your map file. Have a look at the supplied example mapfile (keymap-sample.txt) to see how to create your own keyboard mapping.

When the emulator runs in fast forward mode, and you want to type text, it can be annoying that the emulated system detects multiple key events due to the key repetition of the emulated system. To avoid this you can disable the key repetition in fast forward mode here.

#### The Sound Dialog

Here you can control the sound subsystem.

Check if you want emulated sound at all. Emulation is faster if sound emulation is turned off.

Nine frequencies from low to high quality are available. Experiment a little bit to find out which fits best for your setup. For most modern computers, 44100 Hz or 48000 Hz should be fine. For older or slower host systems, you should use a lower frequency. 12517, 250033 and 50066 Hz are frequencies supported by the STE/TT/Falcon sound DMA.

YM voice volume mixing "ST table" method uses a lookup table of audio output voltage values measured on STF and "Linear" just averages the 3 YM voices.

You can select to record a piece of sound here. Use the Browse button to choose a file. The file name extension that you use (.WAV or .YM) determines in which format the sound is recorded in. The Record sound button is a toggle so you will need to return to the GUI to switch sound recording off again (or to use the keyboard shortcut for that).

#### The Devices Dialog

Check the first checkmark to enable experimental printer support. See the Emulated printer section for details.

As Hatari currently only supports printing to file, click on Browse to select the file to print to. You can enter a new filename as well.

Check the second checkmark to enable experimental RS232 support. The RS232 device is configured according to the settings of the emulated RS232 of the Atari ST. This means Hatari will automatically use baudrate and handshaking as configured for the emulated ST.

Click on Browse to select suitable device files for serial input and output. On Linux a good choice is /dev/ttyS0 or /dev/ttyS1.

Check the third checkmark to enable experimental MIDI support. Click on Browse to select a suitable MIDI device files for MIDI input and output.

midi-linux.txt file explains how to select the correct MIDI device file, how to set up software sound synthetizing on Linux (using Alsa) if your sound card/driver doesn't support MIDI, and how to set up MIDI networking e.g. between multiple Hatari instances.

### Keyboard shortcuts

While the emulator is running, you can activate or toggle various features via Hatari keyboard shortcuts. Below are listed the default shortcut key bindings:

Shortcut | Purpose
ALTGR+a | record animation
ALTGR+g | grab a screenshot
ALTGR+i | boss key: leave full screen mode, pause Hatari and iconify its window
ALTGR+j | toggle joystick emulation via cursor keys on/off between ports 0 and 1
ALTGR+m | (un-)lock the mouse into the window
ALTGR+r | (warm) reset the ST
ALTGR+c | coldreset the ST (same as the original power switch)
ALTGR+d | open dialog to select/change disk A
ALTGR+s | enable/disable sound
ALTGR+q | quit the emulator
ALTGR+x | toggle normal speed/fast forward
ALTGR+y | enable/disable sound recording
ALTGR+k | save memory snapshot
ALTGR+l | load memory snapshot
ALTGR+f or F11 | toggle between fullscreen and windowed mode
ALTGR+o or F12 | activate the options GUI
PAUSE | pause emulation
AltGr+PAUSE | invoke the internal Hatari debugger

You can change the key bindings from the Hatari configuration file. The required key values can be seen in the SDL_keysym.h include file (usually in /usr/include/SDL/).

### Emulated Atari ST keyboard

All other keys on the keyboard act as the normal Atari ST keys so pressing SPACE on your PC will result in an emulated press of the SPACE key on the ST. The following keys have special meanings:

Key | Meaning
Alt | will act as the ST's ALTERNATE key
left CTRL | will act as the ST's CONTROL key
Print Screen | will emulate the ST's HELP key
Scroll Lock | will emulate the ST's UNDO key
Page Up | will emulate the ST's ( key in the keypad
Page Down | will emulate the ST's ) in the keypad

If joystick emulation via keyboard is enabled, by default cursor keys are used for the directions and right CTRL key as the fire button. Otherwise they act as corresponding keys of the emulated Atari ST.

NOTE: Problems with simultenous keypresses most likely aren't an issue in Hatari as many modern keyboards report/support only three simultenous key presses (or even just two depending on which keys are in question). Expensive gaming keyboards support more.

### Emulated mouse

For obvious reasons your PC mouse will act as the emulated Atari ST mouse. In fullscreen mode it will act as expected, directly controlling the ST mouse pointer.

However it is a little bit different in windowed mode. To make the mouse work there as expected you need to grab it first or lock it into the Hatari window. Do this by pressing the ALTGR+m hotkey combination or starting Hatari with the --grab command line option. Press the shortcut key (again) to go back to normal mouse behaviour which allows you to move mouse outside outside the Hatari window while Hatari is up and running. Note: pausing the emulation will also (temporarily) release the mouse grab.

Mouse scrollwheel will act as cursor up and down keys.

### Emulated joystick

The Atari ST joysticks are emulated ofcourse allowing you to play your favourite games with Hatari.

The default mode is to use a connected PC joystick. You can use any joystick that is supported by your kernel. If your joystick works with other applications, it will likely work with Hatari as well. Make sure it is calibrated and then off you go. Move the stick to point into the desired direction. Please note that Hatari will not detect analogue movement as the Atari ST only had digital joysticks. The first firebutton will act as the normal firebutton on the Atari ST while the second firebutton will emulate a keypress of the SPACE key on the ST as many ST games utilize the SPACE bar for secondary game functions. (Xenon for example)

If you do not have a PC joystick or joypad, then you do not need to desperate. You can emulate one of the two Atari ST joysticks via the cursor keys. Just activate it in the GUI. Then the cursor keys will act as the joystick directions, the right CTRL key will act as the firebutton. You can still use the cursor keys as the ST's cursorkeys in this mode as long as you press SHIFT along with the cursorkeys. You can also configure these keys from the joystick options.

### Emulated video

Hatari emulates all screen modes of the original machine.

ST/STE shifter overscan effects are emulated, but due to the fact that these effects are achieved by using quirks and glitches in the original chips to do things beyond their specification, emulation is a bit tricky for these effects. As a result, some demos using these techniques might not be displayed correctly in Hatari, known ones are listed in the compatibility.html file.

Beside that you can setup extended VDI modes. These only work with GEM-compliant applications and they are equal to fitting a videocard into your Mega ST.

Make sure to disable extended VDI modes for playing games as 99% of all ST games will not be able to make use of higher resolutions.

### Emulated printer

Due to the fact that printer handling is very different between Unix style machines and the Atari ST, emulation of the printer is achieved by writing all printer output to a file.

The file will contain a sequence of data, the same that would appear on the data pins of the Atari ST printer port. That would include control characters and commands for graphic printing. Clicking "Print desktop" on the GEM desktop would result in a messy data dump in the printer output.

Printer emulation works best for plain text files or programs that do not format the output for a specific printer. The file contents can be used with your favourite text editor for further processing and printing to a real printer.

To get real direct printing out of Hatari on a PostScript printer, you may set up a GDOS printer with a PostScript driver on the emulated Atari and set your printer device file as Hatari's printer output.
NOTE: This has not been tested yet and the Hatari team cannot guarantee that it will work.

### Emulated RS232

Serial communications in Hatari is designed to directly use a serial port on your PC.

Communications parameters are set automatically upon the settings of the emulated ST. This means all you do is to set the communication parameters like baudrate from your ST communications software. Hatari will do the rest and handle the serial input and output for you.

## Floppy disk images

Hatari does not use floppy disks directly but disk images due to differences between the floppy disk controllers of the ST and the PC. Three types of disk images are currently supported: The raw "ST" type, the similar "DIM" type and the compressed "MSA" (Magic-Shadow-Archiver) type.

The raw type (file suffix should be "*.st") is simply a sector by sector image of a real floppy disk. You can easily create such an image with the dd program which should normally be pre-installed on every Unix-like system. Simply type something like dd if=/dev/fd0 of=myimage.st to create a disk image. Of course you need access to /dev/fd0, and depending on your system and the type of floppy disk you might have to use another device name here (for example I use /dev/fd0u720 for 720kB disks). However, if the disk is copy-protected or doesn't use a MSDOS compatible file system, this might fail. So be very careful if you are not sure about the disk format.

The other possibility is to image the disk on a real Atari ST. There are programs like the Magic Shadow Archiver for this task. Hatari supports this slightly compressed MSA disk images, too. Note that Hatari only supports the "old" MSA format, there are some Magic Shadow Archiver clones (like Jay-MSA) that create better compressed but Hatari-incompatible disk images. However, if you have got such a MSA disk and want to use it with Hatari, you can still run the corresponding MSA program within Hatari to extract the incompatible disk image to a normal floppy disk image.

While *.ST and *.MSA are more or less the "standard" types of Atari disk images, you might sometimes also find STT or ADF images on the internet. These currently do not work with Hatari.

Hatari can now also utilize *.DIM images just as *.ST ones without any problems. Note that DIM images are nearly the same as the raw ST images (they only have an additional 32 bytes header), so you can easily transform the DIM images into ST images by stripping the header from the files. For example try something like: dd if=input.dim of=output.st bs=32 skip=1

If you've got a disk image that has been created with the old ST emulator PaCifiST (for DOS) or with early versions of the program Makedisk, and the disk image does not work with Hatari, then the disk probably suffers from the "PaCifiST bootsector bug" (Hatari will display a warning message then). In this case, the bootsector of the disk contains some illegal data, so that the disk even does not work on a real ST any more. However, if it is a .ST and not a .MSA disk, you can easily fix it by using a hex-editor to change the byte at offset $D (13) from 0 to 1 (don't forget to backup your disk image first, since you can also easily destroy your disk image when changing a wrong byte there). If the disk contains a bootsector program, you probably have to adjust the boot sector check sum, too (it can be found at offset $1FE + $1FF).

Hatari supports disk images that are compressed with (Pk-)ZIP (file suffix must be ".zip") or GZip (file suffix must be ".st.gz" or ".msa.gz"), so you can archive your disk images into zip archives. You can also directly run the zip archives you may download from the net as long as the archive contains a disk image in .ST or .MSA format.

Note: Hatari does not save disk images back to *.ZIP files so your highscores and savegames are lost if you load the game from such a zipped disk image.

## Hard disk support

Hatari supports three ways of emulating Atari hard drives: The low-level ACSI and IDE hard disk emulation and a GEMDOS based drive emulation. In most cases the GEMDOS based hard disk emulation is best as it allows exchanging files easily between the emulated and the host environment.

Please note that changing the HD-image or the GEMDOS HD-folder will reset the emulated Atari since it is not possible to switch the hard disk while the emulator is running.

On a 32-bit host system, the size of a hard disk image is limited to 2 GB. On 64-bit host systems, bigger images might be possible but the support for bigger images is not tested very well yet.

### GEMDOS based hard disk emulation

With the GEMDOS based drive emulation, you can easily "mount" a folder from the host file system to a drive of the emulated Atari. To use the GEMDOS based drive emulation, you should use a folder on your hard disk that only contains files and folders with valid TOS filenames i.e. file and folders names shouldn't contain invalid GEMDOS filename characters and their length shouldn't exceed the 8+3 file name length limit.

If you provide --harddisk option a directory containing only single letter subdirectories, each of these subdirectories will be treated as a separate partition, otherwise the given directory itself will be assigned to drive "C:". In the multiple partition case, the letters used as the subdirectory names will determine to which drives/partitions they're assigned.

GEMDOS drive emulation is an easy way to share files between the host system and the emulated Atari, but there are also some known limitations which are due to the way the GEMDOS drive emulation is implemented:

- It is not possible to use a cartridge image at the same time with the GEMDOS drive emulation (Hatari has it's own cartridge code that is used for GEMDOS emulation).
- As MiNT installs its own GEMDOS handler, it doesn't work with the GEMDOS drive emulation. MiNT needs to be booted from a real hard disk image.
- GEMDOS drive emulation conflicts with the ACSI and IDE harddisk images. If you want to use GEMDOS HD emulation and ACSI/IDE disk images together, use a multiple partition GEMDOS emulation setup and select the partition subdirectories (letters) so that they don't conflict with the ACSI/IDE drive partitions (letters). With HD Driver you have also another option, see Using HD Driver with GEMDOS partitions.
- The GEMDOS drive emulation does not work (very well) with TOS 1.00 and 1.02. Use at least TOS 1.04 if you want the GEMDOS drive emulation to work properly.

So, if your programs complain that they could not find/read/write files on the GEMDOS emulated drive, you should try to copy them to a floppy disk image or a real hard disk image!

### ACSI hard disk emulation

To use the ACSI hard disk emulation, you need a hard disk image file with a pre-installed HD driver in it. You can try to get an image of your old ST hard disk or grab one from the internet (e.g. from the Hatari website).

To create a new ACSI hard disk image, you can start with an empty image that you have created for example with the following command: dd if=/dev/zero of=hd.img bs=512 count=xxx (where 'xxx' is size in 512 byte blocks). Copy the complete AHDI 5.0 package to a floppy disk image, then boot Hatari with this floppy disk image and the fresh hard disk image like this: --acsi hd.img ahdi.st. Then start HDX.PRG from the floppy disk and format + partition the hard disk image with it.

Formatting and partitioning works currently only with AHDI 5, but you can install the AHDI 6 driver to the hard disk after it's formatted. Restart the emulated system, run AHDI.PRG from the floppy disk to access the hard disk image from the emulated Atari and then run HINSTALL.PRG. After installing the hard disk driver to the fresh HD image with HINSTALL.PRG, you can boot directly from the hard disk image.

### IDE hard disk emulation

As the IDE disk format (little endian) differs from the ACSI disk format (big endian), you need separate disk images for them. Hatari doesn't currently support formatting IDE disks with AHDI, but you can do it with Cecile.

First create an empty image file with the size of your choice with: dd if=/dev/zero of=hd.img bs=1k count=xxx. Then get the Cecile hard disk driver from http://centek.free.fr/atari/softs/s_cecile.htm and put it on a floppy disk image (e.g. to one named "cecile.st" using: zip2st.sh cecile.zip).

Run Hatari with hatari --machine falcon --tos tos404.rom --ide-master hd.img cecile.st, switch to larger color resolution and warm up your French language skills. Then start the Cecile hard disk driver CECILE.PRG and run CC_TOOLS.APP to partition your hard disk image. Click the "Partition" button, select "Hatari IDE disk" and set suitable partition size with the arrows (below type field). Then click "Valider".

If you only want to use your HD image in Falcon mode, you can install the Cecile hard disk driver to the image from the Cecile CC_TOOLS.APP: Click the "Installer" button and save the Cecile driver to the 1st partition on "Hatari IDE disk". If you want to also use your HD image in ST/STE mode, you need to get and install AHDI 6 driver on it instead (see ASCI hard disk emulation section).

Then you can boot from your hard disk image by simply specifying it with the --ide-master parameter.

## Moving files to/from hard disk images

Moving files to and from Atari hard disk images can be done either through GEMDOS partitions (host directories mounted inside Hatari emulation) or accessing the images directly on the host (outside the emulation). Both have their own limitations.

If it's fine for the IDE/ACSI partitions to be first, you can use hard disk images with AHDI or Cecile driver and a multipartition GEMDOS setup as described in above sections. If you want to boot from a GEMDOS partition i.e. such to be before hard disk image partitions, and still to be able to access all the IDE/ACSI partitions, you need to use HD Driver.

### Using HD Driver with GEMDOS partitions

Uwe Seimet's HD Driver works fine with both the Hatari GEMDOS partitions and normal hard disk images. However, it doesn't work with EmuTOS so you need real TOS (at least version v1.04).

First copy the HDDRIVER.PRG binary into your GEMDOS drive emulation directory AUTO folder. Then start the HDDRUTIL.APP configuration utility, locate HDDRIVER.PRG, open the "Devices and Partitions" dialog and select the "Preserve Existing Partitions" option. Then you can just start Hatari with your hard disk image and this GEMDOS directory, for example like this: "hatari --harddisk gemdos-hd/ --ide-master ide-hd.image".

If you're using the demo version of HD Driver, you can write files only to the C: partition, i.e. in above case only copy files from the hard disk image partition to the GEMDOS partition (with some write slowndowns included into the demo version). If you want to copy files to the hard disk image with the demo version of the HD Driver, you need to set the hard disk image as drive C:.

To accomplish this, set the GEMDOS partitions to be from D: forward, i.e. have a directory which contains only single letter subdirectories, starting from "D" like in "mkdir gemdos-hd; mkdir gemdos-hd/D". Then give Hatari (as the last parameter) a boot floppy image containing the demo version of HDDRIVER.PRG in its AUTO folder, like this: "hatari --ide-master ide-hd.image --harddisk gemdos-hd/ hd-driver-floppy.st".

### Accessing HDD image partitions outside of Hatari

If you want to access the harddisk image partitions also outside the emulation, the disk image needs to have a DOS partition table. The atari-hd-image script included with Hatari can be used to create such an image.

Inside the Hatari emulator, EmuTOS can access partition(s) on these kind of images directly without any driver software. Of the Atari HD drivers mentioned above, Centek's Cecile and Uwe Seimet's HD Driver (demo) work fine with these partitions. E.g. AHDI and CBHD don't.

Note that plain EmuTOS supports only ACSI and the listed HD drivers support only IDE (emulation). Cecile needs TT or Falcon and HD Driver doesn't work with EmuTOS. To summarise; if ASCI emulation and EmuTOS are enough, use those. Otherwise, if you want to use TT or Falcon emulation, use Cecile (or full HD Driver version if you have it), otherwise use HD Driver (demo).

To access the content of the partitions on Linux host, there are two possibilities:

#### Using Mtools

For this you need to add an entry for the hard disk image to your ~/.mtoolsrc and specify which partition you want to access from the image. For an image created with the above mentioned script, the line in the configuration file should look something like this:

    MTOOLS_NO_VFAT=1
    drive c: file="/home/user/hatari/hd.img" partition=1

Note that Mtools is instructed to use FAT compatibility mode because EmuTOS cannot deal properly with VFAT file information. If you don't want this setting for all your Mtools drives, you can set it also via the environment like this ("::" refers to the drive image given with the "-i" option):

    MTOOLS_NO_VFAT=1 mcopy -spmv -i hd.img files/* ::

#### Using a loopback device

This is recommended even by Mtools documentation, but it's less convenient as it requires root rights. First you need to "loop" mount the image:

    $ su
    # image="hd.img"; mountdir="hd"
    # start=$(parted $image unit s print | awk '/ 1 /{print $2}' | tr -d s)
    # losetup -f $image -o $((512*$start))
    # loop=$(losetup -a | tail -1 | cut -d: -f1)
    # mkdir -p $mountdir
    # mount -t msdos $loop $mountdir

This uses parted to find out the first partition offset in sectors and then tells losetup to bind the first free loop device to a corresponding offset from the hd.img image. mount is then used to mount the file system from the loop device on top of the "hd" directory.

After you've copied the relevant files to the "hd" directory, you need unmount the file system and remove the loop device binding before using the disk image from Hatari:

    # umount $mountdir
    # losetup -d $loop

## The debugger

Hatari has a built-in debugging interface which can be used for analyzing code that runs in the emulated system. To invoke the debugger, press the AltGr + Pause key combination.

If you start Hatari with the "-D" command line option, m68k exceptions will automatically invoke the debugger. You can toggle this also later from the debugger with the "setopt -D" command.

To run debugger commands at Hatari startup, one can use the "--parse <file>" command line option. This is useful e.g. for debugging TOS or some demo startup code, or if you always want to use some specific debugger setup (breakpoints etc).

The debugger uses Hatari's parent console window, so make sure you run Hatari from the command line when you want to use the debugger. On Linux you can add for example an icon to your desktop that does it with something like this (replace "xterm" with your favorite terminal program):

    xterm -T "Hatari debug window" -e hatari

### General debugger use

At the debugger prompt, type "help" to get a list of all the available commands and their shortcuts:

    Generic commands:
               cd (  ) : change directory
         evaluate ( e) : evaluate an expression
             help ( h) : print help
             info ( i) : show machine/OS information
             lock (  ) : specify information to show on entering the debugger
          logfile ( f) : open or close log file
            parse ( p) : get debugger commands from file
           setopt ( o) : set Hatari command line and debugger options
        stateload (  ) : restore emulation state
        statesave (  ) : save emulation state
            trace ( t) : select Hatari tracing settings
             quit ( q) : quit emulator

    CPU commands:
          address ( a) : set CPU PC address breakpoints
       breakpoint ( b) : set/remove/list conditional CPU breakpoints
           disasm ( d) : disassemble from PC, or given address
          profile (  ) : profile CPU code
           cpureg ( r) : dump register values or set register to value
          memdump ( m) : dump memory
         memwrite ( w) : write bytes to memory
          loadbin ( l) : load a file into memory
          savebin ( s) : save memory to a file
          symbols (  ) : load CPU symbols & their addresses
             cont ( c) : continue emulation / CPU single-stepping

    DSP commands:
       dspaddress (da) : set DSP PC address breakpoints
         dspbreak (db) : set/remove/list conditional DSP breakpoints
        dspdisasm (dd) : disassemble DSP code
       dspmemdump (dm) : dump DSP memory
       dspsymbols (  ) : load DSP symbols & their addresses
       dspprofile (dp) : profile DSP code
           dspreg (dr) : read/write DSP registers
          dspcont (dc) : continue emulation / DSP single-stepping

#### Entering arguments to debugger commands

After writing (with TAB completion) one of the above command names, pressing TAB will (for most commands) show all the available subcommands.

If you want to give numbers in other number bases than the default/selected one, they need to be prefixed with a character indicating this. For decimals this prefix is "#" (#15), for hexadecimals "$" ($F), and for binary values it's "%" (%1111).

By default debugger expects all numbers without a prefix to be decimals, but you can change the default number base with the "setopt" command, just give it the desired default number base (bin/dec/hex). When using the hexadecimal number base, remember still to prefix hexadecimal numbers with '$' if they could be confused with register names (a0-7, d0-7)! Otherwise results from expressions and conditional breakpoints can be unexpected.

#### Calculations and immediate evaluation

Instead of a number, you can also use an arithmetic expression, by surrounding it with quotes (""). An expression can contain calculations with CPU and DSP register, symbol and Hatari variable values in addition to numbers. For example to give a sum of A0 and D0 register values to a command, use "a0+d0".

Within arithmetic expressions parenthesis are used both to change the order of precendence and to indicate indirect addressing. Unlike with conditional breakpoint expressions (explained below), you cannot give size for the indirect addressing, a long value is always read from the RAM address given within parenthesis. For example to get a long value pointed by stack pointer + 2, use "(a7+2)".

Values of arithmetic expressions are always evaluated before being given to a command. Except for "evaluate" and "address" commands, they always need to be marked with quotes (""). Besides arithmetics, this can be used also to give symbol/register/variable values to commands that don't otherwise interpret them. If command complains that it didn't recognize e.g. a register name, just put it to quotes and it will be "evaluated" before being given to the command.

With command argument completion (see build notes), result from the last "evaluate" command can be inserted by typing '$' and pressing TAB.

### Inspecting emulation state

In the beginning, probably the most interesting commands are "m" and "d" for dumping and disassembling memory regions. You can use "dm" and "dd" commands to do the same for the DSP.

    > help memdump
    'memdump' or 'm' - dump memory
    Usage:  m [start address-[end address]]
            dump memory at address or continue dump from previous address.

    > help disasm
    'disasm' or 'd' - disassemble from PC, or given address
    Usage:  d [start address-[end address]]
            If no address is given, this command disassembles from the last
            position or from current PC if no last position is available.

    > disasm pc
    $00aa6e : 2f08                                 move.l    a0,-(sp)
    $00aa70 : 0241 0fff                            andi.w    #$fff,d1
    $00aa74 : 207c 00fe 78c0                       movea.l   #$fe78c0,a0
    $00aa7a : 2070 1000                            movea.l   (a0,d1.w),a0
    $00aa7e : 4ed0                                 jmp       (a0)

Both commands accept in addition to numeric addresses also register and symbol names, like in above example. If you don't specify an address, the commands continue showing from an address that comes after the previously shown data. "disasm" command default address will be reseted to PC address everytime you re-enter the debugger.

You can use the "info" command to see state of specific sets of HW registers (e.g. "info videl") and Atari OS structures (e.g. "info gemdos").

#### Selecting what information is shown on entering the debugger

By using the "lock" command, you can ask Hatari to show specific information whenever you enter the debugger / hit a breakpoint. For example to see disassembly from current PC address, use "lock disasm".

With the "regaddr" subcommand, you see disassembly or memory dump of an address pointed by a given register ("lock regaddr disasm a0"). Of the DSP registers, only Rx ones are valid for this subcommand.

"file" subcommand can be used to get (arbitrary number of) commands parsed and executed from a given debugger input file whenever debugger is entered. With this you can output any information you need:

    lock file debugger.ini

To disable showing of this extra information, use "lock default". Without arguments "lock" command will show the available options (like the "info" command does).

### Debug symbols

You can load symbol name/address information from a file to the debugger with the "symbols" command (and with "dspsymbols" for DSP). These symbolic names can be used in arithmetic expressions and conditional breakpoint expressions. They also show up in the "disasm" command output.

The symbols file format is following:

    e01034 T random
    e01076 T kbdvbase
    e0107e T supexec

Where 'T' means text (code), 'D' means data and 'B' means BSS section type of address. The hexadecimal address, address type letter and the symbol name are separated by white space. Empty lines and lines starting with '#' (comments) are ignored.

AHCC C-compiler can provide a symbol file suitable for this with its "-n" 'nm' list option (not enabled by default). If you're reverse engineering some code, you could just create your own symbols file to help in debugging it later.

If you're debugging normal TOS/GEM programs instead of code loaded into a fixed address (like e.g. EmuTOS is), after the program has been loaded, load the symbols with the program text segment address offset:

    symbols calc.sym "TEXT"

(The value of the above virtual "TEXT" debugger variable comes from a program basepage, it's set after the program is loaded by TOS, see "info basepage" output.)

### Breakpoints

There are two ways to specify breakpoints for Hatari. First, there are the simple address breakpoints which trigger when the CPU (or DSP) program counter hits a given address. Use "a" (or "da" for the DSP) to create them, for example:

    a $e01034
    a some_symbol

Note that address breakpoints are just wrappers for conditional breakpoints so you need to use "b" command to remove or list them.

Then there are the conditional breakpoints which can handle much more complex break condition expressions; they can track changes to register and memory values with bitmasks, include multiple conditions for triggering a breakpoint and so on. Use "b" (or "db" for the DSP) to manage them.

Help explains the general syntax:

    > help b
    'breakpoint' or 'b' - set/remove/list conditional CPU breakpoints
    Usage:  b <condition> [&& <condition> ...] [:<option>] | <index> | help | all

    Set breakpoint with given <conditions>, remove breakpoint with
    given <index>, remove all breakpoints with 'all' or output
    breakpoint condition syntax with 'help'.  Without arguments,
    lists currently active breakpoints.

Unless you give breakpoint one of the pre-defined subcommands ('all', 'help'), index for a breakpoint to remove or no arguments (to list breakpoints), the arguments are interpreted as a new breakpoint definition.

Each conditional breakpoint can have (currently up to 4) conditions which are separated by "&&". All of the breakpoint's conditions need to be true for a breakpoint to trigger.

#### Breakpoint options

Normally when a breakpoint is triggered, emulation is stopped and you get to the debugger. Breakpoint options can be used to affect what happens when a breakpoint is triggered. These options are given after the conditions and are prefixed with ':'.

<count>
  Break only on every <count> hit. For example, to stop on every other time PC is at given address, use:

      a $1234 :2

once
  Delete the breakpoint when it's hit i.e. trigger it only once. It may be useful if you just want to get a specific address. Or if you're on an instruction that jumps back to a start of the loop and you want to finish the loop, you couuld use:

      b pc > "pc" :once
      continue

trace
  Continue emulation without stopping after printing the value that triggered the breakpoint and doing other possible option actions. This is most useful when investigating memory or register value changes (explained below).
lock
  Show the same information on breakpoint hit as you see when entering the debugger (see the "lock" command in Inspecting emulation state above). This enables also trace option as you would anyway see this information if debugger would be entered.
file <file>
  Execute debugger commands from given <file> when this breakpoint is hit. With this you have complete control over what information is show when the debugger is hit, you can even chain breakpoints (as explained in Chaining breakpoints later on) etc. Use this if "lock" option isn't enough or you want different information show on breakpoints and when entering the debugger.

Note: you can give multiple options for conditional breakpoints, but for address breakpoints you can give only one these options. And "file" option is supported only for conditional breakpoints.

#### Breakpoint conditions

"b help" explains very briefly the breakpoint condition syntax:

    > b help
    condition = <value>[.mode] [& <mask>] <comparison> <value>[.mode]

    where:
            value = [(] <register/symbol/variable name | number> [)]
            number/mask = [#|$|%]<digits>
            comparison = '<' | '>' | '=' | '!'
            addressing mode (width) = 'b' | 'w' | 'l'
            addressing mode (space) = 'p' | 'x' | 'y'

For CPU breakpoints, mode is the address width; it can be byte ("b"), word ("w") or long ("l", default). For DSP breakpoints, mode specifies the address space: "P", "X" or "Y". Note that on DSP only R0-R7 registers can be used for memory addressing. For example;

    db (r0).x = 1 && (r0).y = 2

If the value is in parenthesis like in '($ff820)' or '(a0)', then the used value will be read from the memory address pointed by it. Note that this conditional breakpoint expression value is checked at run-time whereas quoted arithmetic expressions (mentioned in Entering arguments to debugger commands above) are evaluated already when adding a breakpoint. For example, to break when a value in an address (later) pointed by A0 matches the value currently in D0, one would use:

    b (a0) = "d0"

If you're interested only on certain bits in the value, you can use '&' and a numeric mask on either side of comparison operator to mask the coresponding value, like this:

    b ($ff820).w & 3 = (a0)  &&  (a1) = d0 & %1100

Comparison operators should be familiar and obvious, except for '!' which indicates inequality ("is not") comparison. For example:

    b d0 > $20  &&  d0 < $40  &&  d0 ! $30

As a convenience, if the both sides of the comparison are exactly the same (i.e. condition is redundant as it's always either true or false), the right side of the comparison is replaced with its current value. This way you can give something like this:

    b pc > "pc"

As:

    b pc > pc

That in itself isn't so useful, but for inequality ('!') comparison, conditional breakpoint will additionally track and output all further changes for the given address/register expression. This can be used for example to find out all value changes in a given memory address, like this:

    b ($ffff9202).w ! ($ffff9202).w :trace

Typically with this one would use the breakpoint "trace" option like above.

#### Breakpoint variables

In addition to loaded symbols, the debugger supports also setting conditional breakpoints on values of some "virtual" variables listed by "b help". For example:

- If you want the emulation to stop on the first instruction of next program; after TOS desktop is up, set a breakpoint on the TEXT segment address given in a program basepage:

      b  pc = TEXT :once

  Note1: It's better to trigger it only once because if you'd leave it on, during reboot you would get a warning for every instruction until TOS sets a valid basepage.
  Note2: you cannot use an address breakpoint for this because value of a variable given to it is evaluated when the breakpoint is set, not at run-time, so it cannot get the new value that the TEXT variable gets when you start a program.
- To find out current program DATA and BSS segment contents, use the corresponding variables:

      m  data
      m  bss

- If you want to stop at a specific cycle within a frame (that is, PC relative to the current VBL/HBL in cycles), set breakpoints to specific "HBL" and "FrameCycles" variable values. If you for example want to break after 20 HBLs, use:

      b  HBL = "HBL+20"

- Aes/Bios/Gemdos/LineA/LineF/Vdi/XbiosOpcode variables can be used to catch AES, BIOS, GEMDOS, Line-A, Line-F, VDI and XBIOS OS-calls. By default they contain the 0xffff value, so to trace e.g. AES calls, one needs to use something like this:

      b  AesOpcode ! AesOpcode  &&  AesOpcode < 0xffff  :trace

Hint: "info" command "aes", "gemdos" and "vdi" subcommands for can be used to list the corresponding OS-call opcodes. For example, to see the GEMDOS opcodes, use:

    info gemdos 1

#### Chaining breakpoints and other actions

As the file pointed by the breakpoint ":file" option (see Breakpoint options) can contain any debugger commands, it can also be used to do automatic "chaining" of debugger and breakpoint actions so that after one breakpoint is hit, another one is set.

For example if you have these input files:

- "break.ini":

      b GemdosOpcode = 0x3D :trace :file trace.ini

- "trace.ini":

      setopt --bios-intercept --trace gemdos,xbios,fdc,io_all
      b VBL = "VBL+4" :trace :file disable.ini

- "disable.ini":

      trace none
      b all

And then start Hatari with the first debugger input file and a GEMDOS harddisk directory containing "desktop.inf" file:

    hatari --parse break.ini -d testdir

1. "break.ini" input file will break when TOS opens the "desktop.inf" file (it's the first Fopen() i.e. GEMDOS call 0x3D done by TOS at boot) and the breakpoint will run the debugger commands from the "trace.ini" file
2. "trace.ini" input file sets Hatari to trace several things (see Tracing section below) in the emulated system for few VBLs until breakpoint runs commands from the "disable.ini" file
3. "disable.ini" input file will disable tracing and remove all (remaining) breakpoints

Note: because debugger input files cannot "continue" emulation, ":trace" option needs to be used for the breakpoint(s) if you want emulation to continue after the breakpoint action(s).

Hint: It's better to test each input file separate before testing the whole chain. Besides the ":file" breakpoint option, these debugger input files can be also read with the debugger "file" command, "lock" command "file" option and with the Hatari "--parse" command line option.

### Tracing

After analyzing the emulation state and/or setting new breakpoints, you can continue the emulation with the "c" command. You can continue for a given number of CPU instructions (or DSP instructions when "dc" is used), or you can continue forever (until a non-tracing breakpoint triggers) if you omit the instruction count.

If you want to continue with real-time disassembling, you can enable it with "trace cpu_disasm" (or "trace dsp_disasm" for DSP) at the debugger prompt before continuing.

Disable tracing with "trace none" when you enter the debugger again. "trace help" (or TAB) can be used to list all the (over 30) supported traceable things, from HW events to OS functions.

Because Hatari normally emulates things at the hardware level, tracing certain Atari OS Traps requires setting additional Hatari options which tell it to intercept this higher level functionality:

- BIOS and XBIOS tracing require enabling of the BIOS intercepting with the "--bios-intercept" option (which has also some other side-effects)
- GEMDOS tracing requires enabling the GEMDOS harddisk emulation (which doesn't work under MiNT because it re-implements GEMDOS)

If use of above isn't possible for the things you'd like to track, you can use the OS call opcode breakpoints explained above with the ":trace" breakpoint option.

Tracing options can be set even from a program within the emulation if you enable the Hatari "--bios-intercept" option and call XBios 255 from the program with a suitable Hatari command line string. Bios interception will also show the (Bios level) CON: output on the host console.

Note that the trace output file can be set only when Hatari starts, it cannot be changed from within the debugger (or emulation).

### Profiling

Profiling tells where the emulated code spends most of its (emulated) time. It can be used to find out where a program is (apparently) stuck or what are the largest performance bottlenecks for a program.

Profiling is used by first enabling the profiler (use "dp" for DSP):

    > profile on
    Profiling enabled.

And profiling will start once you continue the emulation:

    > c
    Returning to emulation...
    Allocated CPU profile buffer (18 MB).

When you get back to the debugger, the collected profiling information is processed and a summary of in which parts of the RAM the execution happened is shown:

    Allocated CPU profile address buffer (4 KB).
    Normal RAM (0-0x400000):
    - no activity
    Cartridge ROM (0xFA0000-0xFC0000):
    - no activity
    ROM TOS (0xE00000-0xE80000):
    - active address range:
      0xe0014c-0xe23f02
    - active instruction addresses:
      707 (100.00% of all)
    - executed instructions:
      629144 (100.00% of all)
    - used cycles:
      9408503 (100.00% of all)
    - address with most cycles:
      0xe0dcca, 402628 cycles (4.28% of all in area)
    - address with most hits:
      0xe004a4, 4900 hits (0.78% of all in area)

(DSP RAM will be shown only as single area in profile information.)

After this you can request more detailed profiling information:

    > profile
    'profile' - profile CPU code
    Usage:  profile <on|off|counts|cycles|symbols|stats> [show count]
    	on & off enable and disable profiling.  Data is collected
    	until debugger is entered again after which you can view
    	statistics about the data or view PC addresses that took
    	most cycles or functions/symbols called most often.
    	You can specify how many items are shown at most.

For example:

    > profile counts 8
    addr:           count:
    0xe004a4        0.78%   4900
    0xe004b6        0.78%   4896
    0xe0dcbc        0.55%   3448
    0xe0dcc6        0.55%   3448
    0xe0f59e        0.55%   3446
    0xe0dcce        0.55%   3445
    0xe0dcd6        0.55%   3445
    8 CPU addresses listed.

If you have loaded symbol information for code addresses, with the "profile symbols" command you get a list of how many times the code execution passed through the defined symbol addresses.

After the profiling information has been post-processed, it will also be shown in the disassembly output.

### Usage examples

Here's a list of some common debugging tasks and how to do them with the Hatari debugger:

Stopping on program startup and examining its data
  Please see Breakpoint variables and Inspecting emulation state sections.
Tracing specific things in the system
  To trace e.g. all GEMDOS calls and IO operations, use:

      trace  gemdos,io_all

  Please see Tracing section for more information on tracing, what's possible with in and what are its limitations.
Stopping when certain PC address is passed Nth time
  To stop e.g. after function/subroutine at $12345 is called for the 6th time:

      a  $12345 :6

Stopping when register has a specific value
  To stop when e.g. D1 register contains value 5, set a breakpoint on:

      b  d1 = 5

Stopping when a register value changes
  To stop when e.g. D1 register value changes, set a breakpoint on:

      b  d1 ! d1

Stopping when register value is within some range
  To stop when e.g. D1 register value is within range of 10-30, set a breakpoint on:

      b  d1 > 9  &&  d1 < 31

Stopping when memory location has a specific value
  To stop when e.g. bit 1 of the Video Shifter Sync Mode byte at IO address $ff820a is set i.e. video frequency is 60Hz, set a breakpoint on:

      b  ($ff820a).b & 2 = 2

Stopping when a memory value changes
  To stop when above bit changes, set a breakpoint on its value being different from the current value ('!' compares for inequality):

      b  ($ff820a).b & 2 ! ($ff820a).b & 2

Tracing all changes in specific memory location
  To see the new values and continue without stopping, use the ":trace" breakpoint option:

      b  ($ff820a).b & 2 ! ($ff820a).b & 2  :trace

Stopping at specific screen position
  To stop e.g. when VBL is 100, HBL is 40 and line cycles is 5, use the corresponding debugger variables:

      b  VBL = 100  &&  HBL = 40  &&  FrameCycles = 5

Stopping after value increases/decreases by certain amount
  To stop e.g. after D0 value has increased by 10, set breakpoint on:

      b  d0 = "d0 + 10"

Single step so that new register values are shown after each step

      lock registers
      c 1
      [new register values]
      c 1
      [new register values]
      ...

Showing current stack contents
  To see first 64 bytes on top of the stack, use:

      m  "a7-64"-a7

Seeing specific information each time debugger is entered
  To see above information whenever some breakpoint is hit, you enter debugger manually etc, write that command to e.g. stack.ini file and then use:

      lock  file stack.ini

  Please see also Chaining breakpoints section for more examples on what you can do with the debugger input files.
Finding where program or OS is stuck
  Profiling tells from which addresses CPU is running executing the instructions:

      profile  on
      c
      [after a while, use AltGr+Pause to get back to debugger]
      profile  counts

Hint: for most of above commands, one just needs to prefix them with "d" (or "dsp" if using full command names) to do similar operation on DSP.

### Build notes

Lastly, the debugger is much nicer to use with the command line history, editing and especially with the command, command argument and symbol name completion support. If you're building Hatari yourself, please make sure that you have the GNU readline development files installed (on Debian / Ubuntu these come from the libreadline5-dev package). Otherwise completion doesn't get enabled when you configure Hatari.

ENABLE_TRACING define needs to be set for tracing to work. By default it should be enabled.

## Performance

Hatari performance varies between Atari programs, depending on what features Hatari needs to emulate for them. Less accurate Atari emulators may be faster as emulation accuracy has a performance overhead.

The operating system and libraries below Hatari can also sometimes have a noticeable effect on performance.

### Improving Hatari performance

Hatari currently runs best in 16 or 32 bits per pixel color depth mode, so try to avoid 24 bits per pixel display modes if possible. 16-bit mode is fastest.

On OSX, frame skipping, zooming and drive LED options (listed below) seem to have a large effect on performance in the windowed mode. This is apparently due to issues in the SDL OSX backend and how OSX itself composites non-fullscreen window contents. OSX uses always 32-bit mode.

Unless you've disabled compiler optimizations (like GCC's -O2 or -O3 options) in the Hatari build, the extra optimization flags (like GCC's "-mtune=i686") don't seem to have very large effect on Hatari performance. Using GCC -O3 option instead of -O2 can give minor (5-10%) performance improvements for things (demos) that use very heavily interrupts.

However, Hatari can be sped up considerably by giving up some emulation or emulator accuracy. Except for DSP, these options should be needed only on very slow devices like handhelds. See below.

If nothing else helps, try an earlier Hatari version. More accurate emulation or emulator output in newer Hatari versions means that they can be slower despite optimizations.

### Emulation options

Emulation options have the largest impact on performance. These options can be changed from the Hatari GUI System dialog and the emulation needs to be rebooted for any of these changes to take an effect!

##### DSP

Emulating the Falcon DSP is performance-wise several times more demanding than emulating the m68k; DSP runs at higher frequency, executes many instructions for each m68k instruction and emulation isn't as mature and optimized. Unless some program needs DSP, none or dummy DSP emulation mode could be used. Even of the programs that do use DSP, many use it only for background music and work fine without the real DSP emulation.

##### Timer-D

The single largest factor contributing to general Hatari emulation performance is the handling of interrupts. Enabling Timer-D patching option (about) doubles Hatari ST/STE emulation performance as it significantly reduces the number of interrupts generated by the emulated Atari machine. Using this has adverse effect only for very rare programs.

##### Compatible CPU

After the DSP and interrupts, m68k emulation takes most time. Disabling the "Slower but more compatible CPU" option will speed up the emulation a lot, but it won't anymore be cycle accurate. This can be fine for many games and other programs, but won't work e.g. for demos using overscan or rasters.

Roughly speaking, for DSP emulation, one needs at least 2Ghz machine. For normal (unpatched) Timer-D frequency on some specific cases (like demos with overscan 512 color animations) one may need over 1GHz machine, but some rare ST/STE demos may require over 1GHz machine even with Timer-D patching. For "Compatible CPU" one needs at least 1/2Ghz machine.

NOTE: Above options may cause some programs not to work correctly. The Hatari Software Compatibility List lists programs known to need real real Falcon DSP emulation or Timer-D frequency. Disabling "Compatible CPU" option is recommended only as a last resort.

### Emulator options

Emulator options don't usually have as large effect on performance as emulation options, but they don't affect the emulated programs at all, just the quality of the emulation "output". These options can also be toggled at run-time without rebooting the emulation.

##### Sound

Internal Hatari sound handling and the SDL_mixer sound thread libALSA sound processing can account up to 1/3 of the Hatari CPU usage in normal ST/STE emulation. Disabling sound will get rid of that. Using low sound frequency or one matching your sound card may also help. Best is if you disable also background music from the programs you run in Hatari as this can significantly reduce the number of generated interrupts.

##### Frame skipping

Screen rendering can take noticeable amount of CPU time. The default Hatari "auto" frame skipping should be used unless there's a good reason not to. It will skip converting and showing some of the frames if there's not enough time for them.

Also, if your monitor refresh frequency is lower than the selected Hatari monitor frequency (e.g. LCD monitors usually use 60Hz whereas Atari monochrome monitor uses 71Hz), you should use frameskip of one. The reason is that if your SDL library uses VSync to synchronize the output to screen (like OSX one?), with zero frame skip that forces the emulation to run slower than a real Atari. If SDL doesn't use VSync, Hatari does redundant work to convert frames you can't see.

##### Zooming

If you are not using frame skip, disabling zooming can have noticeable improvement on performance. You can do this by specifying suitably low "Max zoomed" resolution (--zoom 1 command line option sets it to 320x200). If you still want to have a nice fullscreen mode, you should rather add the right resolution mode-lines (e.g. "320x200") to your xorg.conf file. If you still want to use zooming, disabling borders may help a bit.

##### Spec512 color handling

Handling Spec512 color modes which change the ST/e palette constantly takes some extra CPU. If you have problems with CPU usage in such screens and you care more e.g. from the sound quality than visuals, you can disable the Spec512 mode handling by zeroing the threshold for that with the --spec512 0 option.

##### Statusbar and drive LED

If your version of libSDL uses VSync to synchronize the screen output, drawing of the statusbar or the drive LED may have some minor impact on performance too. Normally they shouldn't.

### Measuring the performance

There are a couple of ways to monitor and measure Hatari performance.

By default Hatari has Statusbar visible and automatic frameskip enabled. When Hatari has enough time that it can sleep a little each frame, the statusbar frame skip ("FS") value keeps at zero. If Hatari is completely busy, it will increase to the maximum specified (automatic) frame skip value.

Hatari has also a facility to measure FPS i.e. Frames Per Second. Just enable the --fast-forward option on command line (or use the corresponding keyboard shortcut), and after a while, press the "Pause" key. Whenever Hatari emulation is paused, Hatari will output on console how many VBLs it could show per second along with some other numbers.

It depends on what you want to measure, but usually it's best to disable sound and set high frame skip like --sound off --frameskips 60 so that the associated external overheads are minimized. E.g. video output can on some platforms do VSync and measurements would then show your monitor refresh frequency instead of actual Hatari performance.

On Unix systems with times() function call, only the time spent by the Hatari process itself is measured. On other systems much less accurate SDL "wall clock" timings are used. To make latter more accurate you could use also --run-vbls option to specify how many VBLs Hatari should run before it exits. In this case it's best to either have the test-case run automatically from the AUTO-folder or given as memory snapshot to Hatari with the frame skip set equal to the VBL count.

Note that the numbers can fluctuate quite a bit, especially when the SDL timings are used, so for (statistically) reliable numbers you may need to repeat the measurement several times. You should of course make also sure that the system doesn't have any other activity at the same time you're making the measurements.

## Appendix

### Copying

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA

The GNU Project and the Free Software Foundation | The GNU General Public License

### Introduction to Emulation

Emulation via software is an art and Hatari is an example of this.

Emulation is to make a computer behave like a (probably) completely different machine on the lowest possible niveau. This includes CPU and custom chip emulation allowing software written for the emulated machine to be run without notice. A good emulator will run most of the software intended for the emulated platform without trouble.

The key to emulation is to simply do those things with a software program, the emulator, that normally chips would perform. So you have an CPU emulator that basically consists of a large loop that does exactly what the real thing would do:

- fetch an instruction from virtual memory
- interpret this instruction
- fetch operands from the emulated registers and memory
- perform the operation like addition or changing the program counter on a jump instruction
- writes results back into the intended registers or memory locations
- increment of the program counter and loop

The typical von-Neumann CPU can be emulated very fast, stable and error-free using such a simple loop system.

But in most cases the CPU emulation is the simplest part. Correct emulation of the various custom chips and hardware parts of the emulated system is much trickier.

| June 2011