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c7086e691c
Probing the SCV reveals that the TV-1 asserts \WAIT when accessed, extending T2 by one T-cycle. This includes uPD1771C accesses (for which the TV-1 decodes address).
46 lines
1.2 KiB
Plaintext
46 lines
1.2 KiB
Plaintext
References
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==========
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https://forums.atariage.com/topic/130365-atari-7800-vs-epoch-super-cassette-vision/ - [takeda.txt]
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http://takeda-toshiya.my.coocan.jp/scv/index.html
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Memory maps
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===========
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CPU memory
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----------
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0000-0FFF uPD7801G internal ROM
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1000-1FFF (undefined; alias of 3000-3FFF?)
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2000-2FFF External VRAM (2*2KB SRAM) - sprite patterns
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3000-31FF EPOCH TV-1 internal VRAM - screen data (char. index / bitmap)
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3200-33FF EPOCH TV-1 internal VRAM - sprite attributes
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3400-3403 EPOCH TV-1 registers
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3404-35FF (unused)
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3600-3600 uPD1771C register
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3601-7FFF (unused)
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8000-FF7F Cartridge memory (ROM, RAM)
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FF80-FFFF uPD7801G internal RAM (128B) - WRAM
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Character memory
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----------------
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000-3FF Character ROM (1KB ROM) - text patterns
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Ports
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PC[0]: pause button - 0=pressed
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PC[3]: uPD1771C \RESET
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PC[6:5]: Cartridge-specific function:
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- 32K ROM + 8K RAM: Overlay RAM enable = PC[5] & &A[14:13]
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- 64K+ ROM: ROM (32K window) bank select: PC[6:5] => A[16:15]
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- 128K ROM (+ 4K RAM): ROM (32K window) bank select: PC[6:5] => A[16:15],
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and Overlay RAM enable = PC[6] & &A[14:12]
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Interrupts
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==========
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INT1: uPD1771C ACK (PB0)
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INT2: Vblank - asserted (rising) on start, de-asserted (falling) on end
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