On Sun, Aug 07, 2016 at 03:52:22PM +0200, Gerrit Heitsch wrote: > On 08/07/2016 03:04 PM, smf wrote: > >AFAICT they originally planned to make a dram version for the P500 and the > >static ram version only happened when the ultimax project picked up the > >chips but they needed to make it cheaper. > > Usually, MOS counted upwards, meaning the 6566 would have come before > the 6567. So either the static version came first or there was another > version, like a 6565. There are a few numbers missing between the 6561 > (PAL-VIC for VIC-20) and the 6566 after all. There seem to have been 6562/6563 and 6564/6565 projects as well. Both didn't pan out. > >The 6509 appears to have been made for the P500 and the 6510 for the > >ultimax. The c64 on the other hand was then just thrown together with > >the chips they had (hence the PLA). > > I read somewhere, that the PLA was used to allow starting the PCB design > before all the logic was ready. With the PLA you could make the PCB and > have a 28pin socket waiting for the guys who did the logic. The PLA, being current mode, is also a lot faster than MOS. The 7700/8700 go to quite some length to be faster. See http://skoe.de/docs/c64-dissected/pla/c64_pla_dissected_a4ds.pdf Segher Message was sent through the cbm-hackers mailing listReceived on 2016-08-07 21:00:07
Archive generated by hypermail 2.2.0.