On 12/20/2012 08:19 PM, Ethan Dicks wrote: > On Thu, Dec 20, 2012 at 2:29 AM, Anders Carlsson > <email@example.com> wrote: >> Bil Herd wrote: >> >>> So while it was known that [some] 257's didn't work well >> >> Am I understanding this correct that whether a C64 (or C128, or other C64 >> related computer) will operate with the CP/M Z80 cartridge to a big part is >> due to which vendor(s) of the 257's and perhaps other 74 series chips are >> installed in the computer? If so, those who have the cartridge and a >> selection of machines could try to verify if it generally holds true. In the >> rare case those chips are socketed, perhaps they could be substituted for >> another brand if a dog slow, 40 column CP/M or other Z80 application is >> desired to run on a C64 in the 21th century. > > I don't think those parts are socketed on any stock C-64 I have 2 C64 where the 74LS257 are in sockets and from the looks they came from the factory that way. Wasn't there a LS-TTL-shortage back in 83/84? That was also the time where MOS started to make their own 'TTL', the infamous 77xx. If you have a broken C64 that has one or more of those 77xx-ICs with MOS logo on the board, replace them first. Just had a 250407 board where the MOS 7709 no longer forwarded A7 from the VIC to the RAM (rather strange looking picture). Replaced with a proper 74LS258 and it works again. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2012-12-20 20:00:45
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