email@example.com wrote: > Hallo Andre, > > I haven't been able to get your board and papers but they are here in Heerlen. > You mentioned not being able to format a diskette: you have to use DS DD 96TPI, > no HD-diskettes! DS DD 48TPI will work as well but unreliable. Yes, but finding the disks is difficult. Anyway, I could read 8050 formatted disks, so the SFD1001 works. Still didn't have time for the 8296D. Thanks for the stuff again! > > About the 6522: Shifting PHI2 means a later negative edge. Hasn't it a negative > effect on the behaviour of the 6522 in any way? You should only shift the rising edge. I think there is a schematic on funet... (marko? I couldn't find any on a quick browse...) You can AND the original and the delayed Phi2 to get the right signal, I think. > > Using a 16550: I only have experience with the 8250 but regarding the problems > I had with the 6551, I only can support you advise using an Intel device in > this case. You only need an extra 74LS139 to generate the RD- and WR-signals. I'm not sure if I mentioned it already, but if you use a RS flipflop that is set when RxD goes low and reset when ACIA register 0 is read, and use the output as rts, you should be able to get higher baud rates too. I haven't tried it so far. (see at http://www.tu-chemnitz.de/~fachat/8bit/hardware/serial/index.html) But, a new byte can then only be received when the CPU has taken the last one, which - in a decent OS - involves some context switching (interrupt latency etc) so the overall performance of the 16550 should be much better still. Andre -- Email address may be invalid. Use "fachat AT physik DOT tu-chemnitz DOT de" ------Fight SPAM - join CAUCE http://www.cauce.org------Thanks, spammers... Andre Fachat, Institute of physics, Technische Universitšt Chemnitz, FRG http://www.tu-chemnitz.de/~fachat
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