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 =====A2000 Motherboard Revisions===== =====A2000 Motherboard Revisions=====
 +
 +^Revision Number^Board Change^
 +|3.9|first 2 layer board, dealer demo only; 256KBx1 memory chips|
 +|4.0|last 4 layer board, has German part number|
 +|4.1|video fix, first 2 layer board released to consumers|
 +|4.2|fix for HITEK type keyboard, by removing two capacitors (the first character typed on the HITEK keyboard was lost)|
 +|4.3|new Gary (MOS) chip used, pull-up resistors added to support it|
 +|4.4|production improvements (previous modifications now included in layout), cost-reduction|
 +|4.5|pull-up on U605 (74ALS245) to support certain accelerator cards with the Signetics buffer chip; KS 1.3 ROM  as the new default|
 +|5|all brown boards, all from Germany, falls into the 'Holy Grail' territory; if you see one of these buy it at any price;  supposed to be a 4.5 with the 256KBx4 memory layout of a rev 6 board|
 +|6.0|new layout for 1 meg RAM chips; all RAM now CHIP memory|
 +|6.1|fix to clean up RAM-retention by adding a reset IC (RAM-retention occasionally caused a guru on power-up though the system would start normally if the left mouse button was pressed); Agnus 8372 (1MB) used|
 +|6.2|fix to get certain expansion boards to work correctly with 256Kx4 DRAMs and Agnus 8372|
 +|6.3| KS 2.04 ROM, Agnus 8375, and SuperDenise 8373 as the new default|
 +
 +Check out [[http://w8.ca/technical/a-2000.shtml]] for some more details.
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Last modified: le 2023/09/12 19:00