> On 2020-03-25, at 15:44, Anders Carlsson <anders.carlsson_at_sfks.se> wrote: > >> "It was also possible, without requiring a VIC-switch, to connect two Commodore 64s to one 1541 floppy disk drive ..." >> >> Has anyone tested that? Is that a fully deterministic/reliable behaviour? > > As far as I know, you need to release the CLK (or is it ATN?) line after using the drive in order to not lock up the chain: > > C64: POKE 56576,PEEK(56576) AND 239 > Plus/4: POKE 1,PEEK(1) OR 1 > VIC-20: POKE 37137,PEEK(37137) OR 3 > > I used to have my Amiga 500 with a parallel cable connected to 1541-II and then either a C64 or VIC-20 also connected. By issuing a such POKE from the CBM side, I was able to store files on the disk and then load it on the target computer. > > A bit clumsy and failure prone if you forget the POKE so you end up in a deadlock but for shorter periods of operation it seemed to work. OK - so basically for alternating access, each computer needs to actively finish the use of the bus with this kind of POKE, right? Otherwise the bus gets locked. Other than that no side effects are to be expected? -- SD!Received on 2020-05-30 01:21:21
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