PDA

View Full Version : 1M x 1 DRAM



Smack2k
March 31st, 2017, 06:02 PM
Is 1M X 1 DRAM useable in a PC?

Curious as I am not sure I've seen this designation before or I am just looking at it wrong and it's just a normal 1 MB Stick of DRAM with 9 1Mx1 chips on it?

Have a 386 board I got that I cannot get to post and it has 8 of these in it. 9 1Mx1 chips on one 30 pin SiMM

krebizfan
March 31st, 2017, 06:11 PM
The early 1 MB SIMMs would have 8 or 9 such chips.

gslick
March 31st, 2017, 06:11 PM
A 1Mbit x 1 DRAM would be something like an NEC µPD421000, OKI MSM511000, or Toshiba TC511000 chip. You would need 9 of them to make a 1MB SIMM with parity.

You couldn't use a single chip by itself for normal RAM in a PC.

Smack2k
March 31st, 2017, 06:17 PM
I have 8 of these in the board (1Mx9) and it will not post. I have removed every card from the board, tried different video cards as the only card plugged in and nothing. Was thinking maybe the RaM was the issue.

Stone
March 31st, 2017, 07:21 PM
You only need 4 sticks to populate a bank.

You only need one bank to run the board.

If you have 2 bad sticks, 1 in each bank, both banks will fail, so it's possible (but not certain) you have 6 good sticks.

If you have 7 good sticks and the bad stick is in bank zero the board will not run.

Try with just 4 sticks in bank 0. Keep replacing 1 then 2 at a time using all possible combinations and you might get lucky.

It would certainly be much easier if you have a 386SX or a 286 board as these only have 2 sticks per bank and the odds of getting lucky would be much greater. :-)

gslick
March 31st, 2017, 07:23 PM
If it is a 386 motherboard it probably needs memory to be installed in banks of four 1Mx9 SIMMs to get a 32-bit wide memory system, so either four SIMMs total in one bank or eight SIMMs total in two banks.

If you have only been trying with all eight SIMMs installed maybe try with just four matched SIMMs installed in bank 0, or however the first bank might be labeled, or try swapping though different SIMMs in the four you are trying together.

Don't have any other obvious ideas to try.

(edit: Stone and myself typing basically the same things at the same time :) )

Stone
March 31st, 2017, 07:33 PM
(edit: Stone and myself typing basically the same things at the same time :) )Ya', I usually draw Chuck as a typing partner but tonite the lottery was different. :-) :-) :-)

Chuck(G)
March 31st, 2017, 08:18 PM
Well, for what it's worth, I still have a 386 board or two that takes the 1Mx1 DIPs. Mine are all Hyundai branded. No problems for years.

Stone
April 1st, 2017, 04:52 AM
And I have a 286 board that takes the 1Mx1 DIPs. :-)

Smack2k
April 1st, 2017, 05:39 AM
I will give the RAM tests a try....

I mis-spoke on the RAM...they are 1Mx9 chips....there are 8 of them....it was late last night when I was looking at them!!

I noticed that the RAM types had some of each in each bank (2 Toshiba and 2 Siemens in Bank 0 and 2 of each in Bank 1) I will try them with similar in each bank and then begin the process of testing each chip by itself in slot 1 Bank 0 to see if one is bad...

Could the cache be an issue to? If the jumpers are set wrong (I dont think they are, but need to check later today) and there is 256K in the board but the jumpers are set to, say, 64K, could that cause the same issue where it wont even post?

Stone
April 1st, 2017, 05:47 AM
I mis-spoke on the RAM...they are 1Mx9 chips....there are 8 of them....it was late last night when I was looking at them!!Not quite correct.

The chips are 1Mx1 and the sticks are 1Mx9.

You don't have 8 chips -- you have 8 sticks or modules and each stick has 9 chips.



Could the cache be an issue to? If the jumpers are set wrong (I dont think they are, but need to check later today) and there is 256K in the board but the jumpers are set to, say, 64K, could that cause the same issue where it wont even post?No, i don't think so.

Smack2k
April 1st, 2017, 09:27 AM
Yeah. That is what I meant. The sticks. I call em chips from time to time!!

Thanks for the info on the cache

Testing the board....could be a bad oscillator. I have 80 MHz replacements so my 33MhZ proc should be fine.