On 03/07/2015 12:31 AM, Jim Brain wrote: > > > I can understand the 6529, since it offers significantly less feature > than the 6522/6526 and bean counters would note that a half functional > 6522 could be squeezed into a far smaller die if redesigned. I can also > understand the 6526 working to fix the issues with the 6522. The 6529 looks like they took just the data register and the output drivers for port A of a 6522 and made it into a stand alone chip. Should be a VERY small die or a die with lots of unused space. BTW: Can you still use the shift register in the 6526 as a sound generator like you could with the 6522 (CB2 sound in PET)? The 6510 > was a substantial upgrade from the 6502, with the BA/AES functionality > and the on chip register, though I suppose one could argue the point. The 6502 already had BA/RDY, it just lacked the tristate buffers for the adress lines and R/W. For what the 6502 was originally intended that didn't matter, for a shared bus design it meant additional buffers that cost money (see VIC-20). Gerrit Message was sent through the cbm-hackers mailing listReceived on 2015-03-07 09:00:05
Archive generated by hypermail 2.2.0.