Atari 800 Emulator for Unix, Version 0.1.5
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    Copyright (C) 1995 David Firth. E-Mail: david@signus.demon.co.uk

    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 1, or (at your option)
    any later version.

This is the version 0.1.4 of my Atari 800 emulator for Unix (consider
it an early Alpha). My main objective is to create a portable freely
distributable emulator (i.e. with source code available). It can be
configured to run in the following ways :-

	1. BASIC mode
	2. CURSES Mode
	3. SVGALIB for Linux Systems
	4. X-Windows

The basic mode is only useful for running programs such as MAC65,
Atari Basic etc. I have had this version running on Linux, SunOS 4.1.3,
Solaris 2.4, VAX/VMS, CBM Amiga (Dice C) and the HP-UX 9000/380.

The CURSES mode is similar to the basic mode, but it also enables full
screen editing capability. Some computer don't seem to support curses
fully - SunOS 4.1.3, VAX/VMS, LINUX (but ncurses is OK).

The SVGALIB version runs at a reasonable speed. The screen dimensions
are limited to 320x200 and is unable to display the overscan modes.
Instead SVGALIB displays the core 320x192 pixels.

The X-Windows version supports graphics but runs *very* slowly. This
appears to be due to overheads with X-Windows.

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Why have I written this emulator instead of using PC Xformer?

A few years ago (85/86) I wrote a small 'test' compiler for the Atari 800
computer (It was never released commercially but has had a commercial
game written in it - Enigmatix released by Page 6). For historical reason
I would always like to be able to keep a usable copy of my first compiler.
This was not possible using PC Xformer since it only runs on MS-DOS and
without access to the source code have no chance of porting it to
future computers. This emulator originally had a text only interface
which is all I needed, but as so often happens one gets carried away :-)

Features
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Note: Not all features are supported on all platforms.

48K/52K Atari 400/800 emulation (optional RAM between 0xc000 and 0xcfff)
OSS Super Cartridges.
Should run on any Unix computer running X-Windows.
Wide / Normal / Standard Playfields.
Joystick controller using numeric keypad.
Paddle controller using X-Windows mouse position.
Display List Interrupts.
Vertical Blank Interrupts.
All Antic Display modes.
Player Missile Graphics with collision detection.
Character vertical reflect, invert and blank.
Files can be stored directly on your host computer via the H: device.
	(H: replaces the C: device which serves no useful purpose)
Reads XFD disk files.
Disk swapping (Crude but works - needs to be improved)
PIL modes - allows memory between 0x8000 and 0xbfff to be toggled
between RAM and ROM.

Bugs / Known Problems
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A lot of colours have the wrong RGB values. Contact me if you know a
way of converting the Atari colours into RGB values. I am using a
lookup table but a lot are just set to cyan (R=0x00, G=0xff, B=0xff).

A few programs cause the emulator to enter its built in debugger. The
reason for this is unknown at the moment. It might be use of undocumented
instructions.

Player missile priority is ignored.

Future Atari 800 Enhancements
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Hardware scrolling - pointless until the screen refresh rate is improved.
GTIA graphics support for ANTIC modes.
Atari 800XL/XE emulation.
Printer support (Print to file + spool on close).
Paged memory using PORTB.
Sound possibly through /dev/audio (don't hold your breath though)

It should be possible to add support for non OSS Super Cartridges. If
you can forward details on how the cartridge works I'll see what I
can do.