I'm just a spectator here, but it seems like this sort of accumulated mass-knowledge should be put into a Wiki. I mean, I want to build Commodore hardware someday, and this sort of advice and data seems very useful to me. On Sunday, March 9, 2014, smf <email@example.com> wrote: > Well, TED does it and it works. >> > > The 6566 was designed while they were waiting for fast enough drams to > use, the 6567 was then hacked so they could get the c64 out of the door. > There is no real way of determining why they did what they did & it's so > long ago their recollection is likely to be incorrect. > > With TED they had the benefit of hindsight and were able to work with dram > manufacturers during the design process. It also wasn't designed for speed > (no sprite dma needed and an additional bad line for colour fetches from > dram etc). > > FWIW the Amiga 1000 ended up using the same scheme as the C64, so agnus > only controlled it's own access to chip ram. The fat agnus designed for the > a500 had the motherboard multiplexers integrated so it controls all access. > The A3000 was the same with a bit of extra magic on the motherboard to > allow the agnus to alternate between two banks of ram so the cpu could have > 32 bit access to it without a new agnus. For AGA they pushed the magic deep > into Alice, so dma could fetch 32 bits but the blitter/copper etc were > still 16 bit. > > > Message was sent through the cbm-hackers mailing list > Message was sent through the cbm-hackers mailing listReceived on 2014-03-09 21:02:11
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