CHIP-8
======

An interpreter for CHIP-8 and SUPER-CHIP
1.1 programs, the little games of the
COSMAC VIP (1977) and the HP 48
calculators, for the Atari ST and its
successors. A GEM program loads the
program; it runs in a full screen mode.

Runs on every Atari with TOS 1.04 or
newer, MagiC or MiNT, in any resolution.
ST Low and ST High are drawn directly,
all other screens through the VDI.
CHIP8.APP is for 68000 to 68060
machines, CHIP8V4E.APP for the FireBee.
CHIP8.RSC has to be next to them.

Starting a game
---------------

File > Open... (Control+O) asks for a
program file (.CH8, .SC8, ...). The
first time, the settings come up; Play
starts the program. After that its
settings are remembered and it starts
at once. Files ending in .SC8 start as
SUPER-CHIP 1.1, all others as CHIP-8.
A program file can also be dropped on
CHIP8.APP, or sent by a desktop that
knows VA_START.

If there is a text file with the name
of the program and .TXT next to it,
Help > Game manual (Shift+Help) shows
it in a window.

The window shows the picture of the
program. Return goes on playing, File >
Restart (Control+R) starts it again.

Controls
--------

The hex keypad

  1 2 3 4    keys 1 2 3 C
  Q W E R    keys 4 5 6 D
  A S D F    keys 7 8 9 E
  Z X C V    keys A 0 B F

The keys are taken by their position,
so on a German keyboard Y is key A.

Joystick and cursor keys

  Joystick   port 1
  Cursors    the same as the joystick
  Space      the same as fire

They give the CHIP-8 keys set in
Options > Controls... (Control+L): up 5,
down 8, left 7, right 9, fire 6 at
first (as in Octo).

Jaguar pad (STE, Falcon)

  Pad        as the joystick
  A, B, C    fire
  0 to 9     keys 0 to 9
  * and #    keys A and B

In the full screen mode

  Esc        back to the window
  P          pause (Pause on the pad)
  Keypad -   slower
  Keypad +   faster
  Help       this manual
  Control+Q  quit to the desktop
  * and #    on the pad: quit

In the window

  Control+O  Open...
  Return     play
  Control+R  restart
  Control+S  settings
  Control+L  controls
  Control+E  view
  Help       this manual
  Shift+Help the program's manual
  Control+Q  quit

Playing in the window

  Esc        stop
  P          pause
  Keypad -   slower
  Keypad +   faster
  Help       stop, show this manual
  Control+Q  quit to the desktop

A click outside the picture or another
window on top stops the program, too.

In the manual windows

  Cursors    scroll (Shift: a page)
  Control+W  close it (also the
             dialog windows)

Settings
--------

Options > Settings... (Control+S) opens
a window that can stay open. Changes
count at once, also for a program that
is running, and are kept for the loaded
program. Alt with the underlined letter
works a button; Alt+P and Alt+S step
through the platforms and speeds.
Controls... opens the Controls.

Platform: CHIP-8 is the COSMAC VIP.
SCHIP 1.1 is SUPER-CHIP on the HP 48.
SCHIP modern is SUPER-CHIP as most
newer interpreters do it. Octo is
SUPER-CHIP with the CHIP-8 quirks, as
most programs of the Octojam expect.

Quirks: the small ways in which the
platforms differ. Choosing a platform
sets them; they can be changed one by
one. If a game does odd things, try
another platform or quirk.

- VF reset: AND, OR, XOR clear VF.
- Load/store I+: FX55 and FX65 move I.
- Display wait: one sprite per frame.
- Clip sprites: cut off at the edges
  instead of wrapping round.
- Shift VX: 8XY6 and 8XYE shift VX, not
  VY.
- Jump to XNN+VX: BXNN adds VX, not V0.

Speed: instructions per frame (60 frames
a second). CHIP-8 games like 7 to 15,
SUPER-CHIP games 30 or more. An 8 MHz ST
keeps up with about 150; above that the
game runs slower. Keypad - and + change
the speed while playing.

Options > View... (Control+E): Full
screen off plays in the window. Invert
shows dark pixels on a light ground.

With BubbleGEM installed, the right
mouse button explains what is under
the pointer.

CHIP8.INF, next to the program, keeps
the places of the windows, the last
folder, the joystick keys, the view and
the settings of each program.

Additions to the original
-------------------------

- SUPER-CHIP 1.1: 128 x 64 pixels,
  scrolling, large digits, flags.
- Four platforms and six quirks to
  choose from.
- Joystick, cursor keys and Jaguar pad.
- Pause, speed keys and this manual.
- Playing in a window, inverted colours.
- A manual for each program (.TXT).
- VA_START and BubbleGEM help.

Differences to the original
---------------------------

- The tone is 440 Hz, on the sound chip.
- Programs run 60 frames a second on
  every screen (50, 60 or 71 Hz); the
  picture is shown at the screen rate.
- Machine code calls (0NNN) are not
  run; the program stops with a message.

Notes
-----

Written using Claude AI tools, design
by Kimchipenguin (Mia)
