On 8/10/2011 3:10 PM, Hoffmann-Vetter, Martin wrote: > Hello, > >> I don't know how relevant it is to CBM floppy drives, but it seems to >> have something to do with chip select lines? > That's one problem when you change an 2332 (rom) to a 2532 or 2732 (eprom). > The 23xx series has many chip select (cs) signals that can be programmed in > the polarity. So the standard 2332 for the PET is non inverted chip select > (cs1) at pin 21 and inverted chip select (cs2) at pin 20. You have the same > problem with some dos roms eg. 901887-01 and 901888-01. That's a 2364 with > one non inverted chip select at pin 20! I have been asked to run a modifed 2364 adapter that allows pin 20 to be inverted on non-inverted. I used a hct86 with a jumper to ground on one side of the gate to alter the inversion of the line. It looks like there might be value in supporting a 2332 with a similar setup. Thoughts? The 6540 adapter I have uses a hct138 to support all of the select lines. Jim Message was sent through the cbm-hackers mailing listReceived on 2011-08-11 00:00:03
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