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

[buggie@ben07.unm.edu (stephen e buggie)]

There is also a chip numbered as "1259" that is fully compatible with the
"256" chips used in Apple ][ ram cards.   Steve Buggie


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 ** Stephen Buggie  UNM-Gallup,  200 College Road,      Gallup NM 87301 **
 ** buggie@unm.edu      IIgs/IIc/IIe  voice: (505) 863-2390 or 863-7504 **
 **   Apple ][ forever... just got back from my 10-year stint on MIR!   **
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 ** Stephen Buggie,  Psychology,   Univ. of New Mexico, Gallup NM 87301 **
 ** buggie@unm.edu                  voice: (505) 863-7504  or  863-2390 **
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Rubywand (rubywand@swbell.net) wrote:


: 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