One row is 2MB each. Other row another 2MB since 386SX is 16bit data path is 4MB total. Not much for 3.11 windows. I find that works better with 8MB and that was on my generic non-cached 386DX-25 PC back in the day and I was testing the extra 4mb sticks for a guy.

Cheers,

pentiumspeed wrote on 2020-06-27, 20:02:

Make sure the 4 chips for parity is correct 1MB x 1 bit, Not 256K x 1bit.

If 4 chips are 4 bits per chip, remove these four.

Cheers,

They match the rest of the goldstar dipps. Any idea what the rsel jumpers mean. I wish I could find the board in th99

candle_86 wrote on 2020-06-27, 23:01:

Any idea what the rsel jumpers mean. I wish I could find the board in th99

It's in the VL82C202 data sheet. You just have to find out whether jumper set means "1" or "0", but your previous experiments should be enough to know:

1RSEL2 RSEL1 RSEL0    Bank 0  Bank 1
2  0     0     0     reserved setting
3  0     0     1      512KB   empty
4  0     1     0      512KB   512KB
5  0     1     1     needs four banks
6  1     0     0     reseved setting
7  1     0     1       2MB    empty
8  1     1     0       2MB     2MB
9  1     1     1     needs four banks

So, RSEL2 selects whether you have 512KB or 2MB per bank, and RSEL1/RSEL0 selects whether you have one, two or four banks. It seems your board only has two banks, and the empty sockets are meant to take 1M x 4 chips as an alternative to 32 of the 36 1M x 1 chips (i.e. only the data bits go into the 1Mx4 chips, the parity bits keep being in 1Mx1 chips). If your RAM chips are OK, your board should work with 4MB at RSEL2=1, RSEL1=1, RSEL0=0.

Did you get into the BIOS? I suspect this board has a 286-like BIOS, in which case you may have to set how much extended memory is present in the CMOS setup.

candle_86 wrote on 2020-06-27, 23:01:

pentiumspeed wrote on 2020-06-27, 20:02:

Make sure the 4 chips for parity is correct 1MB x 1 bit, Not 256K x 1bit.

If 4 chips are 4 bits per chip, remove these four.

Cheers,

They match the rest of the goldstar dipps. Any idea what the rsel jumpers mean. I wish I could find the board in th99

unfortunately I couldn't find any match using the beta version of my project, so I guess there's no record of that biostar in th99 (unless I didn't search deep enough ?)

Yes i can get into bios, its a single screen no second page, it reports 640k and 1408 Extended, so its not physically seeing more than 2mb, ill play with the jumpers more, but ive got all memory slots filled

bios options are Drive A, Dive B, HDD1, HDD2, Video, Keyboard PResent, Date and Time no other settings, im thinking it's an OEM board made by biostar

Going from what I've figured out I think I do have some bad chips, but without a tester I guess I'm going chip by chip until I find the bad one.

Also given that with rsel0 jumperrd and 1'2 not jumperrd gives me 2mb, that points to jumpered being 0 and no jumper being 1, I'm going to test my theory out

candle_86 wrote on 2020-06-27, 19:12:

I tried messing with the rsel jumpers, rsel0 sees 2048, rsel1 gets me 1743mb, and rsrl2 limits it to 512kb. Any combination my max is still 2048, if rsel0, and 2 are selected it's 512kb and rsel 1 turned in with anything is a black screen. Dunno if that helps at all

mkarcher wrote on 2020-06-27, 23:23:

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1RSEL2 RSEL1 RSEL0    Bank 0  Bank 1
2  0     0     0     reserved setting
3  0     0     1      512KB   empty
4  0     1     0      512KB   512KB
5  0     1     1     needs four banks
6  1     0     0     reseved setting
7  1     0     1       2MB    empty
8  1     1     0       2MB     2MB
9  1     1     1     needs four banks

candle_86 wrote on 2020-06-28, 02:16:

Yes i can get into bios, its a single screen no second page, it reports 640k and 1408 Extended, so its not physically seeing more than 2mb

Also given that with rsel0 jumperrd and 1'2 not jumperrd gives me 2mb, that points to jumpered being 0 and no jumper being 1, I'm going to test my theory out

There actually is a fourth configuration input. I assumed it would be a software setting controlled by the BIOS, but it actually is another configuration pin you might have a jumper for. That fourth pin controls whether shadowing is enabled or disabled. 2MB with shadowing enabled would result in 1664MB (640 conventional + 1024 extended).

You write "RSEL0 sees 2048", while this should be the 4MB configuration (110), "RSEL1 sees 1743" (which is an odd number). This should be the 2MB configuration, and it might be 2MB + shadow. With "RSEL2 sees 512" (011) you might hit the "4 banks of 512KB" configuration. The 4-bank configurations on a 2-bank board might see the 2 banks as bank 0 and 3 (or not work at all), so it matches up with the documentation again. To be sure about the jumpers, please match the jumpers with the pins of the VL82C202 chip. RSEL2 should be connected to pin 16 (the pin of RSEL2 that is not connected to ground), RSEL1 should be connected to pin 83, RSEL0 to pin 84 and shadow control should be connected to pin 69. For shadow, no jumper means shadow enabled (around 1664KB for 2MB installed) while jumper installed means shadow disabled (2048KB for 2MB installed). Maybe the jumper labelled "RSEL0" is actually "shadow disable"...

I've got a shadow jumper, memory count doesn't change weather its jumpered or not, also i can't follow the jumpers, from the bottom of the board the only traces i see go straight into the ground plane, and on the top of the board i can't find any traces going to the jumpers

Going over the board looking for the traces I found a model number
386-SX B3 though it doesn't seem to help me find any info about the board

I grabbed a set of 1mb x1 80ns chips on eBay now I'll start unplugging banks so I can find the problem bank or banks

From who seller ebay? PM me with this. I'm looking to modify my Compaq 386/25e kingston memory expansion card from 1MB to 4MB type, this requires 36 x 1MB x 1bit, 80ns or 70ns.

Cheers,

I'm interested too ^^

https://www.ebay.com/itm/1MB-lot-8pc-NOS-Tosh … 872.m2749.l2649

holy nuts that's expensive

Hmm about $2.25 each, actually that is not bad for NOS -and not from China-and it appears it is NOS or seller put them in those original tubes. You might get lucky and only a few out those 8 to fix the memory issue. Good luck !

maxtherabbit wrote on 2020-06-29, 00:54:

holy nuts that's expensive

Good DIPs go for a lot of money lately so think he got a fair deal, no neg reports on that seller and ram is all he sells.
You already know that old printers (not HP though) are some places to get good ram for next to nothing. Got a free IBM old 4019 last fall and knew it used DIPS on it's memory board, found 3.5Mb of dips, matched series, have not tested them yet but free is a good price (and other than China are hard to find in 70 or 80nS). Also got ram out of other free old laser's in last year or two. Took the rest of the printer junk to GW recycle for free (just cost me some gas money) 😀

Made this to check tomorrow what each setting does and log it, and then im gonna match that information to the chipset info above and get a handle on it, then ill know which banks to look at i hope

Good idea ! They appear the same so maybe not quite right ? Or could be. Don't forget that in the BIOS is where you actually set shadowing ram features after setting any jumpers/switches to allow it. It also makes the total ram appear less on many machines (as mentioned above) because of Upper Memory mapping.

Here is how it all works out

also tried populating the empty 8 slots with 1mx4bit chips and it did nothing

Shadow was disabled in the bios

I'm now thinking bank2 has bad chips, unfortunately the banks aren't labeled, but after pulling a single ram IC from each bank, with what i know i with bank 0 enabled and bank 1 disabled it will boot with ram missing in the shorter row, it will also boot with both banks 0 and 1 enabled and only show 2048mb so i found my bank of bad ram it looks like

Shit might actually be worth spinning up some SOJ to DIP adapter PCBs if these prices are going to be a thing

It's a shame there arn't DIPP to SIMM Adapters, i know it would be complicated but boy would it be convenient

Now once ive got it fixed ill document it, and im also curious about the other jumpers but im not gonna touch them if i dont have to, next to the bio and AT plug ive got a 2x6 block of pins that i have no idea what its for, the 128/256 jumper when set to 128 i get a boot error saying my eproom isn't correct, so that switch controls the erproom