ZIP Chip Heartbreak

[jeff.brielmaier@yob.com (Jeff Brielmaier)]

GT>Now I don't have the 6502 pinout in front of me but I seem to remember a 
GT>DMA signal line to the CPU.  Otherwise how would the CPU know to stop 
GT>when a DMA cycle is occourring?

The CPU doesn't know when DMA is occurring.  In an Apple //, if an add-in card 
pulls the DMA* (pin 22 on the slot connector) low, the on-board CPU is 
disconnected from the address bus and the cpu is halted (not fed a clock 
signal).

* KingQWK 1.05 # [PK] * Remember when 4K RAM encouraged efficient programming!

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