> On 2019-08-27, at 00:16, André Fachat <afachat_at_gmx.de> wrote: > > Am 27. August 2019 00:05:07 schrieb silverdr_at_wfmh.org.pl: > >>> On 2019-08-26, at 23:24, Mia Magnusson <mia_at_plea.se> wrote: >>> >>>> It might be easier to do what Commodore has done in the 1570/71 and >>>> use an additional 6526 just for the shift register. Then borrow the >>>> code from the 1571. >>> >>> That would most likely be the solution that requires the least amount >>> of work to get it up and running. >>> >>> Captain Obvious says that the con is of course that it needs a CIA. For >>> a one-off or general DIY project that might not be a problem, but if >>> someone were to order a bunch of PCBs and sell either as a complete kit >>> or ready-built thing it might be troublesome to source CIAs. >> >> Pulling a CIA's shift register off a PLD would be Captain Obvious next >> advice ;-) > > And then you need to add logic to put this CPLD somewhere into the CPU > address space. Yes. > Ok that probably goes into the CPLD as well :-) And yes :-) I have somewhat similar (PIAs parallel port) done for the next Dolphin and its parallel connection. This allowed to drop all the six (sic!) glue logic ICs AND the full VIA/CIA/PIA chip in favour of one CPLD. > You also need to make sure you have the right output drivers. True. Works for me so far but the parallel is a bit different (directly wired to the CIA through USER PORT) -- SD!Received on 2020-05-29 22:57:09
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