André Fachat wrote: >> Since IEEE-488 is dependent upon hand shaking it should work fine. > > Yes, IEEE488 relies on handshaking and the VIA whose timer is used for timeout is still clocked at 1MHz. > > However, I had already experimented with a 2Mhz PET version (clocking my selfbuilt computer with a Fat40 ROM at 2MHz) but it did not work (even though I modified the timeout values). It could be a problem in the clock domain crossing from the CPU to the 6522 VIA. Is it a single clock divided /8 or is it multiple clocks? Also, are the setup and hold times preserved when crossing this boundary? > Now the three alternatives I have: > 1) fix my lpt-ieee488 interface - a mess of wires on breadboard... > 2) simply us a real 4040 or 8250 drive which would involve taking the drives down from the attic > 3) build an ATMEL based lpt-ieee488 replacement, using USB instead of the printer port... XS-1541 already supports IEEE-488 or you can take the XUM1541 design and hack in the IEEE-488 code from XS-1541. http://www.wiwi.uni-frankfurt.de/~andreas/xs1541/ http://www.root.org/~nate/c64/xum1541/ -- Nate Message was sent through the cbm-hackers mailing listReceived on 2010-01-03 19:00:04
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