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      • 1loader-dec
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  • Arcade
    • Asteroids 80%
      • Hardware
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      • Journal
    • Crazy Climber 1%
      • BigSpriteGraphics.pdf
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      • cclimber.asm
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    • Defender 75%
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      • SoundROM.txt
    • Frogger (Sound)
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    • Galaga 5%
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    • Moon Patrol 75%
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      • Hardware
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    • Phoenix 35%
      • Hardware
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      • Background
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      • Scramble HHi
        • phoenixj-func-main2.pdf
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    • Space Invaders
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        • after_start.txt
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  • NES
    • Zelda 5%
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      • Bank0
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    • Kid Icarus 1%
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  • Gameboy
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    • Link's Awakening 1%
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    • Morris Worm 1%
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  • Tools
    • Blend
      • blend.zip

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  • Asteroids Hardware
    • IN0
    • IN1
    • DSW1
    • Other

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 CLCK3KHZ 3 KHz Clock
2002 HALT HALT Switch
2003 SWHYPER Hyperspace Switch
2004 SWFIRE Fire Switch
2005 SWDIAGST Diagnostic Step
2006 SWSLAM Slam Switch
2007 SWTEST Self Test Switch

IN1

2400 SWLCOIN Left Coin Switch
2401 SWCCOIN Center Coin Switch
2402 SWRCOIN Right Coin Switch
2403 SW1START 1 Player Start Switch
2404 SW2START 2 Player Start Switch
2405 SWTHRUST Thrust Switch
2406 SWROTRGHT Rotate Right Switch
2407 SWROTLEFT Rotate Left Switch

DSW1

2800 SWCOINAGE Coinage 0 = Free Play, 1 = 1 Coin 2 Credits, 2 = 1 Coin 1 Credit, 3 = 2 Coins 1 Credit
2801 SWCNRMULT Right Coin Multiplier 0 = 1x, 1 = 4x, 2 = 5x, 3 = 6x
2802 SWCNCMULT Center Coin Multiplier & Starting Lives 1x & 4, 1 = 1x & 3, 2 = 2x & 4, 3 = 2x & 3
2803 SWLANGUAGE Language 0 = English, 1 = German, 2 = French, 3 = Spanish

Other

3000 GODVG AVG/DVG Go
3200 LMPSCNS Bit 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
3400 WATCHDOG Watchdog
3600 SNDEXP Sound (explosion)
3A00 SNDTHUMP Sound (thump)
3C00 SNDSAUCR Sound (saucer)
3C01 SNDSFIRE Sound (saucer fire)
3C02 SNDSELSAU Sound Select (large/small saucer)
3C03 SNDTHRUST Sound (ship thrust)
3C04 SNDFIRE Sound (ship fire)
3C05 SNDBONUS Sound (bonus life)
3E00 SNDRESET Sound (noise reset)
4000:47FF VRAM Vector RAM DVG word 0000-03FF
4800:4FFF VRAMunusd Unused VRAM DVG word 0400-07FF
5000:47FF VROM Vector ROM DVG word 0800-0BFF
5800:5FFF VROMunusd Unused VROM DVG word 0C00-0FFF