Supra RAM Board
 

I have an Amiga 2ooo with a Supra RAM board that has 4 MB of RAM. Recently,the Amiga refused to boot with the Supra board. I pulled the board out and the computer booted fine. Then, I put the board in test mode and it also booted fine--without the RAM.

I found the Supra RAM test disk software and ran it. It tells me "Data bit D5 is probably bad.". How do I find that chip on the board to change it.

Vicky

Not enough information. Was there more than that in the error message?

Error at address 600020 hex.
Bad bit was 00000000 00100000
Data bit D5 is probably bad.

I have no clue.:(

if the parts are in sockets you could just swap them out for known working ones 4 at a time.starting in the first bank.


is it one of these?

http://www.bigbookofamigahardware.co...t.aspx?id=1078

It is.

I already took out the second bank.

That resulted in similar messages for D1, D2 and D4. I really can't be sure of ANY good RAM from this board.

You need a way of testing each chip, I will look around to see if anyone has made a cheap DIL ram tester.

Thank you !!! :):)

did you remove the second bank and leave the others after it in?

that would result in a memory failure as well i think.

if you fill the first bank and completely empty all the others you should be able to use the first one as a tester.
if it has jumpers dont forget to set it correctly to right amount.

I only had two bank of chips. I took the second one out. The jumpers are set correctly.

Vicky

I think you have a zorro slot issue.. try switching slots and/or clean them..

How do I clean them?

Vicky

The message is the same for the other slots I put the card in.

Vicky

a thought did cross my mind,was the card working before?

maybe its worth considering that it "might" not be the memory.the controller might of failed.

two possible ways to test the memory.

get memory tester capable of testing the drams.
or,try the memory in a unit that accepts them and test them that way.

Excelle3nt thought. Yes, the unit has been working properly. Additionally, I don't have another Amiga that accepts those chips to test them or a memory tester.

The board is in Test mode and I am assuming that it does a self-test of the board in that mode.

Vicky

When you put a supra board into test mode, it maps all of the RAM into the address space but doesn't perform autoconfiguration. Thus the OS doesn't "see" any of it, even though it's all there, and you can use Supra's RAM testing tools to verify it.

However the board doesn't do any self tests when you configure it like that.

Were you using this disk? http://amiga.resource.cx/install/SupraRAM-15.dms

The board uses 1Mx1 chips, meaning every chip is 1 bit wide and there's a million bits in it. Thus 16 chips will result in 2 mega bytes of 16-bit wide RAM.

As an example: you saw bit 5 is broken at around address 600020.. The Zorro2 memory area begins at 200000. The first bank is thus 200000 -> 3FFFFF. The second bank would be 400000->5FFFFF, third 600000->7FFFFF, fourth 800000-9FFFFF.

Ok, so that would imply that your faulty chip is on the third row of chips (bank 3) counting from the top. Ok, now we can also take a look at the photos of the card on amiga.resource.

Here's one that's half populated.
http://amiga.resource.cx/photos/phot...res=hi&lang=en

Looking at the pic, you can pretty easily see the numbers through the chip sockets in bank 3, so you start counting from the middle of the card towards the bracket, 0 1 2 3 4 5 and position U35 would have your faulty chip. Perhaps swap it around with chip 0 (U30) of the same bank, run the test again to see if the sticky bit changed places. If it did, you have now found your faulty chip.

Looking back at this thread, you seem to have made your position a little bit more difficult by experimenting. Thus I'll recommend the following:

- Have the RAM board as the only expansion in the computer so that it starts at address 200000.
- Remove all chips from the board.
- Jumper it for 2MB as per the manual at http://amiga.resource.cx/manual/SupraRAM2000.pdf.
- Populate the first bank with some of the chips you removed, be absolutely sure that all chip legs are straight and go into the holes in the sockets without bending under the chip or going on the outside of the socket. be absolutely sure that the notches in the end of the chips line up with the notches in the sockets, else you will ruin the chips immediately on powerup.
- Run the memtest, if broken bits are found, remove these chips, set them aside, replace with chips you haven't tried yet, rerun memtest.
- Once you have 2MB of working RAM, if you have enough chips left over, you can populate the second bank, jumper the card for 4MB and rerun the memtest, again swapping chips if some are sticking and you have some you didn't test yet.
- Carry on as long as you can make full banks with the chips you have.
- Once you run out of chips, hit ebay or some online electronics shop and buy more 1Mx1 chips so you can fill as many banks as you need.

The jumper settings may look daunting, but it works like the document describes. Insert jumper blocks on 2/6 and 2/4 for 2MB, 4/8 and 2/4 for 4MB, 2/6 and 6/8 for 6MB, and finally 4/8 and 6/8 for the full 8MB. You can see the pattern forming. Twos for two, fours for four, etc.

Yes, I am using that disk for testing. I only have the first bank filled. So, where is that chip if I only have the first bank filled ?

the only expansion Card I left in there was the accelerator. I will remove it and try what have suggested and post my results.

Thank you vVERY MUCH for your help.

I removed all the expansion boards. Then, I started with one chip. The memtest told me the next empty socket was probably bad. When I put a chip in it, the message moved to the next empty socket. Then when I got to the last chip in the first bank, the message was that data bit D5 was probably bad.

Now what, *scratches head and frowns*?

did you put the exact same chip back in the last socket? if not, then I bet your ram chips are fine.. since this board uses 1Mx1 chips, you will keep getting memtest errors if you don't fill a bank completely, so ignore the advice about putting in 4 chips at a time..

how many chips did you have in there when you got the D1/D2/D4 error?