PaCifiST
The Atari ST Emulator

PaCifiST is an ATARI ST emulator which runs on a PC under plain DOS (or from a Windows 95 DOS session).  The project was started in April 1996.

The emulator is being developed in both C (for system simulation, sound and internal monitor/dissembler) and in assembly language (for 68000 emulation & screen rendering).  Unlike STonX, a great emulator under DOS, Unix and X, PaCifiST isn't portable because of the assembly language parts and the direct PC hardware access, so it won't be released on other platforms.  Unlike
GEMulator, it can run many games and demos.  GEM-based applications can be used as well.

PaCifiST emulates the following components of an Atari ST:

Motorola 68000
All the 68000 opcodes are supported, there are certainly some bugs left.  Flags after BCD are bogus.  Regarding exceptions handling, some bus errors are triggered, zero divide, illegal instructions as well as trace mode.

Shifter
All 3 native ST graphic modes are supported.  The video building can be screen-oriented (the fastest way) or line-oriented (thus allowing raster effects).   The last mode needs VBE 2.0 for better emulation (256 color mode has limitations).

Yamaha 2149 sound chip
Since version 0.35 emulation is provided on Sound Blaster compatible cards.  The YM2149 emulation is being developed by Arnaud Carré. He also wrote a better Sound Blaster driver than mine, which is used in version 0.4 and up.

Interrupts
ACIA & VBL are OK. MFP Timer A, B (in events count mode) as well as Timer C are supported at this time. NEW: Timer D.  Priorities are not always good.  Also, there is a big constraint: Currently, only one interrupt can occur each rasterline.   This will be fixed one day...

6301 chip
ST arrows are mapped to PC numeric pad.  NEW Mouse & Joystick emulation entirely rewritten.  Most games are playable now.  Also, if no PC joystick is detected, Arrows & CTRL keys will be use to simulate one in Port 1 (providing the NUM LOCK key is turned off)

Serial and Parallel
Serial communication is possible at the Bios level but is not correct in this version.   Low-level Parallel output works well and is redirected to LPT1.

Disks
There are three levels of disk access possible in PaCifiST: GEMDOS, BIOS and Hardware.   With GEMDOS simulation, you could optionally mount any PC directory as an Atari unit.  With BIOS and hardware simulations you will use images of ST disks (simply containing all the sectors in logical order).  BIOS-level allows you to both read and write, unlike the hardware-level which is read-only.

Keyboard Mapping
Not all the keys are well mapped. The numeric pad is used for arrow keys, insert, etc.   If there is no joystick connected to your machine, Arrows & CTRL keys will be used to simulate an Atari joystick in port 1.

PaCifiST
Go to the PaCifiST homepage

This emulator can be downloaded directly from it's homepage.

NOTE: In order to run this emulator, you must have the emulator itself, and a copy of the ROM's from the original system.  The emulator itself is Freeware.  The ROM's are copyrighted by the programmer or the manufacturer. You are only legally entitled to use ROM files if you own the actual game, or a PCB/ROM Cartridge from the game that you are emulating.

ROM's are not available on Back In Time,
but they can be found on the Internet.