MagerValp wrote: > > >>>>> "Andre" == Andre Fachat <email@example.com> writes: > > Andre> The 6551 (as well as the 6525, 6526, 6521) doesn't seem to > Andre> suffer from this as it evaluates the address and select lines > Andre> when Phi2 is high - the 6522 seems to sample them with the > Andre> rising edge. > > Ah. Good to know. I'm about to stick a 6551 in my C64. At least I think that is the case with the 6551, as my C64 used to have a 6551 at the SID socket (with an extra address line...) and it worked - besides the horrible rts/cts handshaking which is not possible with the 6551. Did you have a look at the Sockmaster ACIA6551 fix that builds a hardware flow control? A link is on my site. It is an RS flip-flop that is set when a low-bit arrives (start bit) and that is reset when register 0 is being read. The output is taken as RTS. You only have to assure reseting the flipflop after an error I think (didn't try). I am now using a 16550A in my C64, in place of the ACIA6551. And here I really get reliable 9600 baud (probably more when I reduce the interrupt latency in my OS... :-( Without the hardware handshake (which I didn't know about then) I lost too many chars at 1200 baud already with the 6551 with my selfbuilt OS. 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 Universität Chemnitz, FRG http://www.tu-chemnitz.de/~fachat
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