On 8/26/19 2:02 PM, groepaz_at_gmx.net wrote: > Am Montag, 26. August 2019, 13:53:21 CEST schrieb afachat_at_gmx.de: >> Hi there, >> >> has anyone actually every tried to convert the VC1541 to use the fast serial >> bus of the C128? >> >> As I see it, on the UC3 VIA here http://www.zimmers.net/anonftp/pub/cbm/ >> schematics/drives/new/1541/short-251748-rev.E-left.gif there still are >> >> - Port A0-7 >> - CB1 >> - CB2 >> >> unconnected. These could be used to >> >> - CB1/2 shift out under T2 control and >> - PA0-7: connected to a 74LS164 serial-to-parallel shift-in register >> >> The only other thing needed would probably be a 74LS14 Schmitt trigger input >> driver, a 7406 output driver, and potentially replacing the PB6 drive ID >> input with an SRQIN input, and of course a fly-wire to the IEC's SRQIN pin >> 1. >> >> What do you think? > > you also need some extra synchronisation to eliminate the via bug with > external clocking (which is basically the reason for why its not used in the > 1541). i vaguely remember it being described in either one of the datasheets, > or perhaps application notes. 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. GerritReceived on 2020-05-29 22:59:52
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