Den Thu, 11 Jul 2019 17:18:00 +0200 skrev Gerrit Heitsch <gerrit_at_laosinh.s.bawue.de>: > On 7/11/19 2:37 AM, Jim Brain wrote: > > On 7/10/2019 1:32 PM, laughton_at_cyg.net wrote: > >> > >> Sorry to tease everyone -- it was the '816 I was thinking of. My > >> notion was to run it in parallel with the 6510, not to replace > >> it. In other words, the '816 address bus etc would connect to > >> nothing, but during reads (code fetches) its data bus would have > >> the 6510 data bus copied to it. Then the oh-so-convenient VPA/VDA > >> signals will reveal when the opcode fetches occur. > >> > > As SMF notes, illegal but non "JAM" opcodes will cause the CPU to > > desync. Maybe using a NMOS 6502 would work for the approach, but > > that requires finding a NMOS '02 > > They should be easy enough to find. For example I have a number of > 1541 with dead R/W heads. Since that's fatal for use as a disk drive > they are now only good for parts. One of them even has a 6502C as > CPU, that one should be good for 4 MHz. Side track: Are there generally more working 1541 motherboards than working drive mechanisms around? If so, it seems like a good idea to build an interface that is like the reverse of the electronics on a Shugart compatible disk drive. By doing that, it would be possible to use standard "pc" disk drives on a 1541, or even use a gotek or similar. -- (\_/) Copy the bunny to your mails to help (O.o) him achieve world domination. (> <) Come join the dark side. /_|_\ We have cookies.Received on 2020-05-29 22:26:58
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