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Based to the so called "Garberstreet" RAM card from Briel
Computers - this is a description how to make an own 4 MB-RAM
card
expansion for the Apple IIGS.
In general that RAM-card just is wired for use of 4 pieces of 1
MB SIMM with 30 connection-points and an additional 74 HCT 138
chip
for decoding the access to the SIMM modules.
The most difficult challenge will be to get the SIMM-module
sockets. Those sockets are available for vertical and laydown
plugin.
Those use for the angled laydown plugin are preferred because
otherwise the card gets rather much "out of balance" when
loaded
with the SIMM-modules. The best chance to get such sockets
will be to pick them of from an old AT PC-board or from
one of those
common Adaptors out of those days where you could plugin 4
1MB Modules and replace with the adaptor a 4 MB
SIMM.
When extracting these sockets from the board - take care not to
damage the sockets with to much heat….
that will result in bad contact with the modules !
The
1 MB-modules needed for this project have been used most
commonly in old 286, 386 and 486 PC systems in the years from
1998 to 2001.
The connector needed for the expansion slot of the IIGS has 44
slot connection contacts - 2 sides of with each has 22 contacts.
The cheapest way to get such a connector is to cut it of from an
"old-fashioned" 8 Bit ISA-card from the old IBM Computers…..
Those cards have 56 slot-connection-pads so it that
connection-part is shortened to 44 connection-pads it will fit….
But be carefull to cut that part within the last pads and remove
the goldcovering and adjusting the fit with a fine file and
testing the fit to make sure that the contacts are adjusted /
centered to the clamps of the socket.
Make sure that at least 5 to 7 millimeters of a border are left on
top
to get a clean and strong glue-area
between the socket-connector and the experimental-PCB.
The last page of the description shows how to make a basic
fitting board for the mounting and soldering…..
The pages 2 to 6 show in single steps how to make the
connections with the wiring.
Use thin isolated / covered wire for the task of soldering the
connections and follow the steps as shown in the description.
For better control please donīt mix up tasks / steps ….. it raises
the risk of making mistakes !
And at the end of the tasks / steps - enjoy the additional RAM
in your IIGS !
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