Namco Pac-Man/Memory Mapped I/O
Sprite Attributes (read/write, $4FF2-4FFD)
The twelve bytes from $4FF2 through 4FFD choose sprite number, palette, and flip.
4FF0, 4FF1, 4FFE, and 4FFF are never drawn because the video hardware is drawing 36 columns of tiles instead of 32.
IN0 (read-only, $5000-503F)
Reads return Player 1 joystick, one DIP switch, coin acceptors, and "credit" button
IN1 (read-only, $5040-507F)
Reads return Player 2 joystick, "test" button, start buttons, and "table" button
DIPSW (read-only, $5080-50BF)
Reads return six DIP switches and two solder jumpers
Open bus (read-only, $50C0-50FF)
Reads aren't driven.
Interrupt enable and acknowledge (write-only, $5000, $5008, ... $5038)
If high, start of vblank asserts Z80 /IRQ input. If low, /IRQ input is reset and start of vblank cannot assert Z80 /IRQ input.
Mute (write-only, $5001, $5009, ... $5039)
If low, sound generator DAC and volume multipler is forced to zero. If high, sound generator DAC works normally
Ignored (write-only, $5002, $5004, $5005, $5006, $500A, ... $503E)
These four latched bits exist, but are connected to nothing.
Screen rotation (write-only, $5003, $500B, ... $503B)
If high, the tilemap, sprites, and tiles are rotated 180 degrees. For use in cocktail cabinets.
Coin counter (write-only, $5007, $500F, ... $503F)
If high, the coin counter pin is pulled low.
Sound RAM 1 (write-only, $5040-504F)
RAM is only 4 bits wide: top 4 bits are ignored.
The exact interpretation of these nybbles depends on the contents of the sound sequencer ROM.
The stock ROM uses
- $5045: Voice 1 waveform selector (bottom 3 bits)
- $504A: Voice 2 waveform selector
- $504F: Voice 3 waveform selector
Sound RAM 2 (write-only, $5050-505F)
RAM is only 4 bits wide: top 4 bits are ignored.
The exact interpretation of these nybbles depends on the contents of the sound sequencer ROM.
The stock ROM uses:
- $5050-5054: 20 bits of waveform pitch as a fraction of 96kHz
- $5055: Voice 1 volume
- $5056-5059: 16 bits of waveform pitch
- $505A: Voice 2 volume
- $505B-505E: 16 bits of waveform pitch.
- $505F: Voice 3 volume
Sprite coordinates (write-only, $5062-506D)
Big number = top right corner.
Bytes at $5060, 5061, 506E, 506F exist but aren't used
Ignored (write-only, $5070-50BF)
No hardware listens to writes in these addresses
Watchdog reset (write-only, $50C0-50FF)
A counter is incremented every vblank. Writes to this address clear this counter. When 15, the CPU and the registers at $5000-5007 are reset.
