On 6/13/2018 5:07 PM, silverdr@wfmh.org.pl wrote: >> On 2018-06-13, at 19:53, Jim Brain <brain@jbrain.com> wrote: >> >> implement if the 64 requests the transfer. The issue, as I understand >> it, is if you want to surreptitiously DMA data into the running 64 >> memory map, since you don't know where the 6510 is in it's instruction >> fetch/decode/action cycle, and pulling DMA low will corrupt CPU >> activities in flight. > Roger that. I am about something a litte different though. Something like: the CPU puts some data into a buffer and goes about its other businesses. Once it returns it finds the data processed by a DMA capable circuit that reads the data left by the 6502/6510, processes it and writes back to the same (or another) RAM area. All that without actually stopping the CPU. I heard there were some DMA implementations that worked in such way. > I don't think you need DMA for that. Using shared memory (PHI clock sharing, like I have implemented before) will accomplish the bulk of what you want. You'd only need DMA if you want to push the memory into the second CPU faster. You could. DMA a block of memory from local to remote. CPU is stopped for this action Have second CPU operate on data Set a flag CPU watches for the flag (or interrupt). When found, DMA the memory back Jim -- Jim Brain brain@jbrain.com www.jbrain.comReceived on 2018-06-14 08:00:59
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