Upgrading AMS from 128k to 512k

[jedimatt42]

I've got an AMS 128K card that looks like it needs some reconditioning. It is hanging during the AMSTEST program. So I'm thinking I should probably refresh the 74LS612N memory mapper chip on it... In SAMS Memory Tester v4.0 it hangs at the step testing the mapper's retention. I think... In AMSTEST v1.3 it hangs saying it is testing retention, but the [*] marked sections seem like they indicate it isn't done with Memory address lines..

 

Screen from SAMS Memory Tester v4.0

https://goo.gl/photos/un7EQvnTkr1j4BU68

 

Screen from AMS Memory Tester v1.3

https://goo.gl/photos/2mXRrbdiMQFwL4VM7

 

Anyway, I figure I'll find a memory mapper chip online somewhere, and replace that, but while I'm in there I'd like to upgrade the SRAM chip to 512k as well.

 

The documentation with the board says the upgrade is a set of instructions and 'the necessary chip'

 

There is an obvious jumper to move from 128k to 512k setting. Does anyone have one of these in 512k configuration or knowledge of which SRAM chip is used in the upgrade?

 

Also, I'd love to see the text of those upgrade instructions if anyone has them as well.

[Shift838]

I've got an AMS 128K card that looks like it needs some reconditioning. It is hanging during the AMSTEST program. So I'm thinking I should probably refresh the 74LS612N memory mapper chip on it... In SAMS Memory Tester v4.0 it hangs at the step testing the mapper's retention. I think... In AMSTEST v1.3 it hangs saying it is testing retention, but the [*] marked sections seem like they indicate it isn't done with Memory address lines..

 

Screen from SAMS Memory Tester v4.0

https://goo.gl/photos/un7EQvnTkr1j4BU68

 

Screen from AMS Memory Tester v1.3

https://goo.gl/photos/2mXRrbdiMQFwL4VM7

 

Anyway, I figure I'll find a memory mapper chip online somewhere, and replace that, but while I'm in there I'd like to upgrade the SRAM chip to 512k as well.

 

The documentation with the board says the upgrade is a set of instructions and 'the necessary chip'

 

There is an obvious jumper to move from 128k to 512k setting. Does anyone have one of these in 512k configuration or knowledge of which SRAM chip is used in the upgrade?

 

Also, I'd love to see the text of those upgrade instructions if anyone has them as well.

 

This may help you.

 

I just realized this is for the Super AMS card. Sorry.

AMS Schematic and Notes.pdf

Edited August 22, 2015 by Cschneider

[Shift838]

I seem to remember an old message posted on the Yahoo group a couple of years ago or so by Ksarul that if it's the original Asgard 128k memory card and not the newer SAMS card then it would take extensive modification to upgrade it.

 

The SAMS card is a newer card and has 2 x 128k or you can go 2 x 512k and simply change the jumper.

 

Can you verify which one you have?

 

If you have the SAMS card, I believe I may have a couple of chips to increase it to 1mb, I would have to check.

Edited August 22, 2015 by Cschneider

[jedimatt42]

The card is the Asgard card with a single 128k chip, no empty socket. Just one jumper. It currently has a TC551001PL-10 SRAM chip in it.

[Shift838]

Maybe Ksarul can chime in, but about the post he made a while back to tell you how hard it will be to upgrade it.

 

I have an original Asgard 128 myself and there is no jumper to select anything else.

Edited August 22, 2015 by Cschneider

[jedimatt42]

Ok, so mine's not so 'original' It is a REV B, from what looks like late 1992. there is a jumper next to the SRAM chip that is clearly labelled 128k for one position and 512k for the other...

[Shift838]

Then you may be able to. Mine is an original with no jumpers.

 

I know I have the below 512kchip as I had to buy 3 in a lot to get the 2 that I needed to make my SAMS 1mb. Not sure if it will work on your Asgard 128k card but if you can find out then we can probably work on getting it to you.

 

Part Number: HM628512CLP-5

 

You would need to compare it with your current chip for voltage, etc to see if it is compatible to be used.

​

Edited August 22, 2015 by Cschneider

[jedimatt42]

That chip looks extremely promising. The pin differences are that A18 on your 512k hitachi chip is labelled 'not connected' on the toshiba 128k chip, and A17 on your hitachi chip is chip-enable-2 on my smaller chip. CE2 is AND'ed with CE1 to feed the internal CE. That all smells like a feature designed to address multiple chips.

 

I'll pull the card, and study what the jumper actually does. Looking at the differences, it would make sense that it binds CE2 to CE1 for 128k, or that same pin to A17 instead for 512k.

 

And I still need to check the power aspects... And I think I need to replace the memory mapper chip

[jedimatt42]

Yep, that's exactly what the jumper on the board does... although my description there was a bit muddled... The jumper in 128k mode connects CE2 of a 128k sram to Vcc on the mapper, which is the same pin as CE1 on that sram chip.

 

For a 512k chip, the jumper in that position connects the pin position ( which is now A17 on the 512k sram chip ) to another mapper output pin.

 

Looking at the data sheet for HM628512CLP-5, that 512k chip looks like it should be a good fit to upgrade the AMS 128k/512k card.

 

I've gone ahead and ordered a new mapper chip. If that fixes the function of the board, I'll PM you about the 512k chip.

[jedimatt42]

Early last week, I got 2 of the memory mapper chips (TI 74LS612N) and tried them both. The AMS memory test program still hangs in the same respective places for both the AMSTEST program versions I have.

 

That leaves me suspecting the memory, even though the memory claims to test successfully. I doubt it can be testing the pattern successfully when the test program itself is loaded in that memory. So at least a chunk of memory is not being tested. Unless maybe the program execution is entirely out of scratch pad ram. I suppose that is easily possible once the screen is set up.

 

The sram chip is I am guessing the best next thing to test. (It might have been the first best thing, but it's too late for that )

 

I have a MiniPro TL866CS. Is there any reason I wouldn't trust it to conclusively test the sram?