Re: RAM for GS?

[spec@vax2.concordia.ca (Mitchell Spector)]

In article djkc6ssf@sonic.net (David Jackson) writes...

>Hi I have an Apple //GS, ROM ver 0(?),

    Well first off, you should look into upgrading the ROM.
Most programs written in the past 11 years require the 'ROM 01'
firmware, including all versions GS/OS (that means you'll only
be able run System 3.2 at best).

    If the machine only says "Apple IIgs" at the top of your
screen when powered up, then you definitely have the original 
ROM. If you see a copyright notice along with the ROM version 
reported on the lower half in addition to that, then it is a 
ROM 01 or higher. Unfortunately, the free upgrade from Apple 
expired a few years back, so you'll have to buy the chip from 
a vendor like Alltech Electronics or pull it from a dead board.

>with a memory expansion card with all open sockets. Shows Total
>RAM 512K, I think.

    If that is the Apple manufactured card it starts off at 256K,
can be increased to 512K, and finally up to the maximum of 1024K
(1 full megabyte). You'll want to fully populate it to 1 MB, as
that was the standard amount for the majority of programs, not
to mention the absolute *minimum* requirement for current System
Software to run.

    As most will point out, if you want to do anything serious
with the computer, you will need 2-4 MB of memory. Today, 4 MB
is the standard amount of RAM for an Apple IIgs.

>What chips do I ask for to upgrade this memory board?

    You need 256Kx1 DRAMs, rated at least 150 ns and that use
CAS before RAS refreshing (Column Address Selection before Row
Address Selection). They'll have a marking such as "41256-15"
or similar. You can commonly find them on old PC, XT and AT
motherboards--that is, any PC board lower than a 386. I often
see them at thrift shops and used shops for under $1 for the
logicboard, or under $5 for the whole computer.

    I'm not sure exactly how to identify chips that use the
wrong refresh method, but here are some to avoid that do:

- OKI chips with the code "M41256-15" made in Japan, with the
  date code "6Y043"
- Samsung chips with the code "KM41256-15" made in Japan
- NEC chips made in the UK
- NEC chips made in Japan and have "P" as the first letter in
  the date code

    Generally, the best thing to do is plug them in to the
board (short both jumpers after doing so) and then plug it
into the IIgs and run a memory diagnostic program to verify
they're working and the right type of chip. AppleWorks GS
has a program included to do this, or you could use the
Apple II<x> diagnostic software that was had by authorized
dealers and floating around on FTP sites.

Mitchell Spector
spec@vax2.concordia.ca