Hello Ruud, email@example.com wrote: > Just FYI, I hope you remembered that I succeeded in replacing the 6510 of the > C64 and the 6502 of several CBMs/PETs/VIC20 with a 65SC816. Yes, I remember this. But there are different problems when replacing a 8500/01/02 with a plain 6502: the bus can be tristated with AEC, on-chip I/O port and finally the strange GATE IN signal on the 8501. This seems to be the only challenge here, since there are plans to replace a 6510 already, in the 2MHz project from 64'er. I don't like some details there, but the general idea is usable. I can even ignore the I/O port for the first experiments, because the Plus/4 doesn't really need it for memory management like the C64. Only the cassette and serial port are connected there. So it is mostly a task of tristating the bus (with '244 and '245 buffers) and maybe gating the R/W signal. > This uP hasn't a > PHI2 either. I created this signal by delaying the PH0 signals thru two 74F04 > gates. I know by experience that this delay is essential because a Atom Acorn > refused to operate at all without this delay. But to be honest, I never tried > the circuit on a C= without this delay. Phi2 is only available from the processor in the C64, in the C128 it is generated by the VIC-IIe and in the Plus/4 it even comes out of the PLA. So this is just opposite to what you did: I will use a processor that does output Phi2 to replace a processor that does _not_ output Phi2. So I will just leave it alone and unused, since the system already has it's own Phi2. Nicolas - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org.
Archive generated by hypermail 2.1.1.