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Re: Crosspost: Did the cpu influence the display?

Darren Salt wrote:


True. But the *layout* of the display memory was certainly influenced by the
CPU.


In the case of the Apple II, the (somewhat unusual) layout of display
memory was a consequence of using the video refresh to accomplish the
refresh of the DRAMs.

The result is that no special refresh circuitry is used, and, since
all video accesses occur on the alternate half-cycles not used by
the processor, there is never any interference with the processor
for video or DRAM refresh.

A little cleverness simplifies a lot.

-michael

Music synthesis for 8-bit Apple II's!
Home page:  http://members.aol.com/MJMahon/

"The wastebasket is our most important design
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