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[voyager]

A Small question about 72 pin sdram.

I am about to replace the defect socket on my derringer 030, before doing that I would like to test the existing socket with a other 72 pin sdram, just to make sure it is the socket and not the SIMM.

There are a lot of 72 pin SIMM’s out there but nobody tells if they are 5v or 3,3 volt.

I tried google but I can’t figure this out.

I seems to me that 5v 72 pin SIMM’s are the most common right? So the SIMM I pull from old pc main board is most likely to be a 5v one??

Or did pc’s 486 etc use 3,3 volt SIMM and did only amiga and some appel used 5v SIMM’s?

Or maybe 3,3 volt is only used in devices like printers etc.

I just want to make sure I do not blow up my derringer by fitting a 3,3 volt SIMM.
Kind Regards
Sebastian,-

[rkauer]

3.3V SIMM are used mainly on printers.

But it is easy to know if they are 5V or not: just look at centre of the SIMM. 3.3V ones have a voltage regulator (normally a "round" chip).

[banzai]

Also, that notch in the middle acts as both an orientation key and voltage overload preventer. If you have the 5V, that notch will be about dead center. If it's 3.3V, then it's moved a bit to the left, and will not fit the socket.

Note: at this time, many manufacturers were making chips that ran on either 3.3 or 5 volts - they sensed the voltage, and adjusted automatically. Although mainly used for cache on 486/586 systems, there were a few that made SIMMs using said chips, and they had a wider notch that allowed insertion into either 3.3 or 5 volt sockets.

In short, if the SIMM isn't the right one, it won't fit the socket. Go for it!

banzai

[Zac67]

PS/2s are 5V (at least 99.9% of 'em).

[delshay]

sdram? for simms

[Zac67]

Wikipedia:SIMM

[Effy]

Just be careful that you get simms from which you are sure it will work in the Amiga. I once bought 2 modules of 128 Mb 72 pins EDO Ram used on a HP9000 server. Simm is simm, not ? Appearantly not, I burned my BPPC and A1200 motherboard with them :-o Turns out that some datalines were not at the same place as normal simms :boohoo:

[voyager]

Today I was going to replace the SIMM socket. A friend of my gave me some SIMM’s and I expected that the derringer board would say no dram found, but it did.

It now seems the 16 MB SIMM has a small fracture some ware. I assumed that the seller of the card always used the card with this SIMM but its more likely he just put it in there and never checked.

So again thank all of you for the SIMM information ;-)

The Derringer has 9 GAL’s . The board is 16 years old now and the GAL’s will work for another 4 years after that its going to lose its programming. Well oke not directly but the will fail.

I’am thinking, maybe it’s a good idée to make backups, this will be a lot of work I have to remove all the GALS en reading them with a eprom programmer and put them back on the board.

So what do you think, is it a good idée to make backups or not?

[rkauer]

voyager wrote:
--zip--
The Derringer has 9 GAL’s . The board is 16 years old now and the GAL’s will work for another 4 years after that its going to lose its programming. Well oke not directly but the will fail.

--zip again--

So what do you think, is it a good idée to make backups or not?

Yes, it's a good idea. Only one major problem: PAL (and GAL) have a read-protection bit who could be set (or not, depends on the programmer/owner), as the same as the PIC series.

If the chips are not protected, yes, is a good thing to do.