Simm compatibility for Apple IIgs ram cards - potential FAQ addition

[roughana <andrew.roughan@writeme.com>]

I have a whole heap of Simms from an unknown source.
How can I tell if they should work in a IIgs RAM card or not?
(The answer to the following questions would be a great addition to
the CSA2 Hardware Hacking FAQ - I didn't see anything like this in
there.)

I've done some searching on chip numbers in google to determine what
the individual chip capacity is. This can be used to calculate what
the simm capacity is.
 e.g. there are 8 * 256x1 chips on the simm -> 256k capacity
there are 9 * 256x1 chips on the simm -> 256k with parity
2 * 1Mx4 (Number of Words = 1M, Bits Per Word = 4)  -> 1MB capacity
8 * 1Mx1 -> 1MB
9 * 1Mx1 -> 1MB with parity

Is there any general rule that 2/3 chip simms don't work and that you
need to use 8/9 chip simms?

Another post on this topic indicated that the simm must support CAS
before RAS refresh. I haven't yet found this type of information for
any chip that I have searched on so far. How can this be determined?
e.g. available spec sheet info for one chip is
http://www.datasheets.org.uk/specsheet.php?part=GM71C4400AJ70

Should there be a spec sheet for the simm itself?

What RAM cards exist that use simms?
OctoRAM (MDIdeas), Sirius RAM, GS-Sauce, Q-RAM GS, Megaram (4MB card
made by Scarlan Computing Services in Australia), any others?

Maximum capacity of a simm that is supported by any of these cards is
1MB. So don't bother trying higher capacity simms (2MB, 4MB etc)

I've tried a few simms that did not allow me to boot GS/OS. Variety of
symptoms: Fatal error 681; thermometer doesn't move etc. Then I tried
4 * (1MB capacity with parity) simms in my Megaram card and GS/OS
boots but then I get an error when I try to do something in Finder.
Why is this? Bad refresh? Bad RAM chip?

All enlightenment greatly appreciated.

Cheers,
Andrew