On 2013-06-18, at 22:54, Ingo Korb wrote: >> Jim Drew raised the issue that the 1541 board timing had a problem >> with fast SRAM, and that 120ns was about the fastest that worked >> without corruptions. >> ( http://www.lemon64.com/forum/viewtopic.php?t=41396 ) > > I suspect he is wrong about that and/or the control circuit for his RAM > was badly designed. Two of my 1541s (an older one with PCB 251830 and a > 1541-II) have no problems accessing a 70ns 62256 SRAM chip. That adds to my question: how accessing own SRAM chip can be badly influenced by what is there in the remaining areas of the 6502 address space. The way I understand it, what is needed to properly access SRAM (of any speed) in such system is proper processing of clock and r/_w signal from the CPU itself. This should end with timed feeding the SRAM with _CS and R/_W signals but if I build the expansion - it is me who process the signals.. Or am I missing something? -- SD! Message was sent through the cbm-hackers mailing listReceived on 2013-06-18 23:01:12
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