Re: Apple brand II GS Ram card-- 1MB

["Jason Whorton" <jason@microxl.com>]

Whoa.  What a bargain.  If anyone needs 24 RAM chips, go to the thrift store
and buy some old PC's.  It will be cheaper.

Thank you,
Jason Whorton
http://www.microxl.com/oldcomputers/main.html

Rubywand wrote in message <36AE82D3.4D4FDAFC@swbell.net>...
>
>
>Dennis Fenton writes ...
>>
>> There are two jumpers on the Apple II GS memory card. If the card is
fully
>> populated should both jumper blocks be present or absent? Or, should one
>> be on and one off? If so, which?
>>
>
>     Both jumpers should be present. The standard Apple IIgs 1MB Memory
>Expansion card can be usefully configured for 256kB, 512kB, and 1MB.
>
>
>     For 256kB, the top left 8 sockets (i.e. the left half of the top
>row) should be filled. No jumpers should be placed on the pins near the
>lower right end of the board.
>
>
>XXXXXXXX--------
>----------------
>                         O O (no Jumpers)
>                         0 0
>
>
>     For 512kB, the entire top row of sockets should be filled. The
>bottom
>pair of pins should be jumpered.
>
>XXXXXXXXXXXXXXXX
>----------------
>                         O O
>                         0-0 Jumper bottom pair
>
>
>     For 1MB, all sockets should be filled. The top and bottom pairs of
>pins should be jumpered.
>
>XXXXXXXXXXXXXXXX
>XXXXXXXXXXXXXXXX
>                        O-O Jumper top and bottom pairs
>                        O-O
>
>
>> Also, do all the chips have to be identical in speed as well as size?
>>
>
>     Mixing speeds and types is fairly common. (Usually, users try to
>have the chips in each 8-chip set as similar as possible in terms of
>speed.)  The standard speed for the RAM used seems to be 120ns - 150ns.
>If you mixed in a somewhat faster chip, say, 70ns, there should be no
>problem.
>
>     Size needs to be 256k x 1 and the type should be compatible with
>the NEC D41256C DRAM-- like a Hitachi HM50256. (For some weird reason,
>the 41256 number is also used by some makers for 32k x 8 SRAM chips; so,
>you can not just order any "41256" RAM chip.)
>
>     Alltech (760-724-2404) may still be selling a "1MB Expansion Kit"
>of 24 256k x 1 DRAM chips for $24.00.
>
>
>
>Rubywand