VOGONS


First post, by randi

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Hello there, I tried to add some 44256 DRAMs to a 386sx board, but the board responded with beeps and did not POST. Before trying that RAM again I was thinking of trying changing RAM settings Ii was surprised at how many settings AMI allows access to compared to Award), but wished to ask pls , have you ever heard of someone who bricked his board this way (i.e. a CMOS reset wasnt sufficient?) thanks
R

Reply 1 of 6, by SScorpio

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No, switch back to the original RAM that was working. And unplug it from power along with disconnecting the CMOS battery if possible if you need to confirm it's been reset.

There should be compatible and optimal profiles in the BIOS. Try choosing compatible then try the swap again. That should put the RAM timings at the most conservative. You can then try dialing them in. But generally a reset CMOS should have pretty compatible default settings already. You weren't mixing different types of memory, and you had enough sticks?

Reply 2 of 6, by randi

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thanks, no I wasnt mixing , just 4 chips of 44256-10 . The MB was old enough to still support 44256 chips, and I thought the board would look neat with them populated.
The ram I had previously on the board were SIMMs , speed -80, those booted fine. The motherboard spec just mentions "DRAM access time: 80ns" but am I safe to assume thats the fastest ram the board can take? This AMI bios only has a"default settings" profile, should I tweak by adding a clock tick tor two to every setting in the list till it boots and then dial down? Any setting I should start from?

Also I noted that apart from causing the beeping, the 44256 chips on the MB ran hot , however when I tested them each in an (arduino based) DRAM tester, they ran cool & passed testing. thx

Reply 3 of 6, by Horun

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What exact motherboard model ? What exact 44256 ram dips ? If they ran hot then possibly wrong dip pinout compared to what the board needs...

Hate posting a reply and then have to edit it because it made no sense 😁 First computer was an IBM 3270 workstation with CGA monitor. Stuff: https://archive.org/details/@horun

Reply 4 of 6, by randi

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thanks, will get back with the exact 386 MB model when I return home, but I still have the ram datasheet on my phone. I know the MB has only two jumpers related to ram, an optional parity jumper and a pipeline jumper.
From my arduino dram testing I think the general pinout is that expected. In the spec the -10 has the lowest max power tolerance, so possibly it started life as a -7 and was rated to -10 after quality control tests at the factory
It looks like I will need to find a way to map the timing specs in the data sheet to the settings AMI bios allows to be changed (which is quite alot)

Any suggestions from where to start? thanks

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Reply 5 of 6, by DaveDDS

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Any time you "brick" a system due to BIOS settings being incompatible with hardware that worked before you made
settings changes - you can recover it by removing all power, removing the CMOS battery and leave it long enough for any
residual charge in caps. within the CMOS circuit to discharge (you can usually hurry this by grounding the CMOS power pin
- sometimes this is as simple as connecting the two leaves that used to touch the battery you just removed.
(obviously do all this without power on the machine)

Dave ::: https://dunfield.themindfactory.com ::: "Daves Old Computers"->Personal

Reply 6 of 6, by randi

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Thanks, I tried adding wait states to every setting in my OP. But apart from not being recognized (it only saw the simms in the other bank) the dram 44256s still ran way too hot. I was surprised at the specs saying they can reach 70C / 158F
The hottest chips I can tolerate with my finger is 50C for 30 seconds.

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