@Fortis, post #1
@amizet, post #2
@Fortis, post #9
@Fortis, post #9
Rev 4.3 tweaked a few pullup resistor values, to adjust for differences in the new CSG-made Gary chip (a full custom part) versus the Toshiba-made Gary chip (a gate array). After some 150,000 or so A500/A2000s, the CSG Gary was phased in. Rev 4.4 I believe made some changes to filtering of the TICK line, to account for some new power supplies that had been particularly noisy on that line. Rev 4.5 increases the value of the pullup resistor on the BAS* line of the expansion bus; there was a strange problem in conjunction with expansion bus DMA turnaround (what happens after a DMA device gives the bus back), BAS*, certain vendors of the 74ALS245 buffer that sits between BAS* and the local bus's AS*, and accelerator cards that could cause crashes. Add a 1K or so pullup to pins 11 and 20 of U605 on pre-4.5 boards to fix this problem (this was the only severe problem addressed by any subrevision).
@Fortis, post #14
@strim_, post #28