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Four lines will identify to the RAM/ROM selector which RAM/ROM mode to select.

MODE0,MODE1,MODE2,MODE3 will define 1 of 16 modes.

MEMRQ, RD and RW will synchronise the operation.


Logged in as:guest: 1:guest ** :./data/ROMSelect

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Page0NotesRAM Page addrROM Page addrTechnical NotesThoughts.
RAMExternal ROMCS--No internal access, external ROM selected.
1RAM74000H-ALL RAM in memory.
2RAM78000H-ALL RAM in memory.
3RAM7C000H-ALL RAM in memory.
4RORAMRead Only Ram70000H-Ram Write Protected
5RORAMRead Only Ram74000H-Ram Write Protected
6RORAMRead Only Ram78000H-Ram Write Protected
7RORAMRead Only Ram7C000H-Ram Write Protected
8ROM16K ROM-0000H16K ROM / 16K RAM
9ROM48K ROM-0000H48K(16K) ROM
10ROM128K ROM-4000H128K Base ROM
11ROM-8000HNot yet certain what to put here.
12RAM/ROM Microdrive ROM70000HC000HPage In/Out on memory location
13RAM/ROM Multiface ROM74000HE000HPage In/Out on NMI
14RORAM/ROM Non-Specific70000H-RAM Half Write Protected. Memory Page In
15RORAM/ROM Non-Specific74000H-RAM Half Write Protected. NMI Page In.