Gerrit_Heitsch@ibase.stgt.sub.org (Gerrit Heitsch) (06/02/91)
>I recently traded in my A500 for an A2000 at a good price, it was >cheaper than the UK price for a Bodega Bay (take the US price and >apply $1 -> 1pound), The A2000 had a card marked A2000 1Mb expansion >with 512k on it and 16 empty chip sockets. I tried populating >the board - extra memory does not appear. Oh oh, seems that you have got an old A2000A. Try to change it against a A2000B. With the old A2000 you cannot use 1 MB Chip annd the ECS. >There is a set af jumpers, by tial and error I found one position >that gave me the extra memory and gurus. Does anybody know what the >jumpers should be set to ? (assuming the sockets can be populated) >Once they are set correctylt I can start worrying about locating bent >pins on the chips I put in. The position that gave you the extra memory and the Gurus seems to be the right. But with this card theres another Problem. Some years ago a friend of mine had the same problem. He tried different 41256 RAMs, but none of them worked. He fixed this problem by using 41257 (he 7 indicates Nibble-mode), because the board seems to have a strange timing. There is another problem with some of these boards. They use a Waitstate ! There is a workaround for it, but you can only use it, if all Chips are 41257, so you have to remove the 16 soldered chips and replace them by _socketed_ 41257. I believe that no VLSI-Chip should be soldered in or on a PCB because of replacement. Thats why I hate SMT... Thanks to C= that they socketed nearly everything important in the A2000, but they have forgotten to socket the RAM. If somebody knows a way to use normal 41256 please write to me, because the 41257 are hard to get and cost more than normal 41256. Hope it helps Gerrit -- Via DLG Pro v0.97b Gerrit Heitsch - Moenchweg 16 - D-7038 Holzgerlingen phone : ++49 7031 49812 (voice only) UUCP : gerrit@ibase.stgt.sub.org - FIDO : 2:244/7253