Asteroids Hardware

There is 1K game RAM, 2K vector-RAM, 2K vector-ROM, and 6K game ROM.

The CPU runs at 1.5MHz.

The MMI interrupt is clocked at 250Hz.

The upper address line is ignored. Thus the interrupt vectors beginning at FFFA map to the ROM space at 7FFA. The ROM was assembled with 6000-7FFF addresses and not E000-FFFF.

The DVG and CPU share the memory space from 4000-5FFF (8K bytes). The DVG reads this as 4K words. The address mapping is shown above. Only half of the RAM/ROM space is actually populated. There is room for expansion.

IN0

2001 3 KHz
2002HALT
2003Hyperspace Switch
2004Fire Switch
2005Diag. Step
2006Slam Switch
2007selfTestSelf Test Switch

IN1

2400 Left Coin Switch
2401Center Coin Switch
2402Right Coin Switch
24031 Player Start Switch
24042 Player Start Switch
2405Thrust Switch
2406Rotate Right Switch
2407Rotate Left Switch

DSW1

2800 0 = Free Play, 1 = 1 Coin 2 Credits, 2 = 1 Coin 1 Credit, 3 = 2 Coins 1 CreditCoinage
28010 = 1x, 1 = 4x, 2 = 5x, 3 = 6xRight Coin Multiplier
28020 = 1x & 4, 1 = 1x & 3, 2 = 2x & 4, 3 = 2x & 3Center Coin Multiplier & Starting Lives
28030 = English, 1 = German, 2 = French, 3 = SpanishLanguage

Other

3000 AVG/DVG Go
3200Bit 1 = 2 Player Start Lamp, Bit 2 = 1 Player Start Lamp, Bit 3 = RAMSEL, Bit 4 = Left Coin Counter, Bit 5 = Center Coin Counter, Bit 6 = Right Coin Counter
3400Watchdog
3600Sound (explosion)
3A00Sound (thump)
3C00Sound (saucer)
3C01Sound (saucer fire)
3C02Sound Select (large/small saucer)
3C03Sound (ship thrust)
3C04Sound (ship fire)
3C05Sound (bonus life)
3E00Sound (noise reset)
4000:47FFVector RAM DVG word 0000-03FF
4800:4FFFUnused VRAM DVG word 0400-07FF
5000:47FFVector ROM DVG word 0800-0BFF
5800:5FFFUnused VROM DVG word 0C00-0FFF