Roger, Phantom is active low, and open collector. That's why it is *phantom. Could use a germanium diode in series with d-flipflop to s-100 bus pin. This is how people with cromemco floppy fdc cards shadow for the on board eprom/roms.
Rick Bromagem norwestrzh via N8VEM-S100 <[email protected]> wrote: > > > > > > >>> Impossible to tell from the description below Roger. > >>> Post the schematic > >>> John > >Not really a schematic, more like a diagram. The address selection on the >LS688 wasn't actually implemented on the card. The LS688 was hard wired to >recognize "FF". And, the LS244's (U3, U4, U5) were not used. Instead, the >LS245's provided on the buffered prototype card were used. Also, the control >signals shown on one LS244 (in the diagram) are actually spread out over a >number of LS245's as provided on the buffered prototype card. I think there >are a total of 5 LS245's used. Oh, and there is a bicolor LED attached to >pins 5 and 6 of the LS74 so that I can check the state of the flip-flop >visually. I doubt that has anything to do with the problem? > >Roger > > > > > > > >-- >You received this message because you are subscribed to the Google Groups >"N8VEM-S100" group. >To unsubscribe from this group and stop receiving emails from it, send an >email to [email protected]. >For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "N8VEM-S100" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
