486SX and memory problems

[Gurm]

Umm... folks...

You're forgetting here...

If they're 30pin SIMMS they must go in in sets of 4.

Now since you mentioned 16mb modules, I'm gonna go out on a limb and assume that they're 72pin SIMMS. That means pairs.

Now... all KINDS of things could go wrong here.

I'd bet my bottom dollar that the BIOS has never been upgraded, and may very well have been hardwired for 4MB chips.

I'd hunt for the motherboard on the Internet and make sure the BIOS was up to date... then I'd do as suggested above - make sure that they're FPM, not EDO, and put them in in matched pairs.

- Gurm

[xortam]

OMG ... I was wrong! I checked The Hardware Bible site and youse guys were right about the data widths. I blame it on senility.

[Gurm]

So I've been studying for my A+ certification, and this is the kind of shit that's on there. Can you believe it? I keep reading sample questions like "Which IRQ is the mouse port on?" and saying "what's an IRQ?" Hehe.

- Gurm

[villerk]

Okay, so let's get this one straight, m'kay?

The computer has only 2 SIMM slots. I don't have the manual or anything at all.

I have 4 4MB SIMM's. Two of them are double-sided and obviosly exactly alike. This is what's printed on them: "2x32 66AN SCM32230USH70 APAPAM9622". They have silver connectors. The third one is one-sided: "SCM36100UASG70 ATATHT9335" and it has golden connectors. The fourth one is double-sided, but differs from the other two so, that it has uneven number of chips on its sides: "HYM536100M"; it has golden connectors (BTW these are not what's written on the chips, but some other labels).

I have also one 8 MB SIMM. It reads: "E2x32 7BDR HYM532224 AW-60 AEW". Silver.

These are the two one-sided 16 MB SIMM's: "MTBD432M - 6X 973BAA4Y2.071 EDO" (hey, what the heck, that really is EDO... am I blind or something ). Silver.

The funniest thing is that I can use any two 4MB SIMM's at a time. It makes no difference. I can even use any 4MB and that 8MB SIMM, but the computer only finds 8 MB total. If I try to install those two (EDO, of course) SIMM's it won't boot. Maybe I should try to find a mobo capable of using EDO RAM and get on with it...

[KvHagedorn]

Oh my God.. I remember all this stuff.. I'm getting old!

[Dilitante1]

from the description of the memory you have, NONE of it is compatable. Older boards like your "dinosaur" need true parity ram. You have a mix of FPM (70ns no parity) and EDO. You might want to pick up some old ram keychains to find good ram

Again as stated earlier, they must be installed in matching pairs.


-pickle

[DosFreak]

Probly needs 80ns FPM Sims.

and 486SX25 + 95=big NO! 95 craaawwleedd on my 486dx2/66. Dos 6.22/Win 3.1 for that bad boy.

[Gurm]

Nah, he probably doesn't need parity (this IS a 72-pin system after all, so it was one of the nicer boards). The 4mb chips work, after all.

Of course 4+8 = 8, since the 8 is acting as a 4 (and will likely turn up memory errors in that configuration).

Good luck finding non-EDO RAM nowadays. Go to your local PC builder and see if they have a "junk parts" bin.

- Gurm

[Wombat]

yes, we're talking about 486s here. The 386 had significant differences between the SX and DX, but with 486, it was whether or not the x87 unit was severed.

[Wombat]

The board with the uneven number of chips is very likely ECC.


Also, a lot of boards can't match a double-sided SIMM with a single-sided one, and some won't handle double-sided SIMMs at all.

[villerk]

from the description of the memory you have, NONE of it is compatable

Huh? Why does it work so well then with two 4MB SIMM's?

and 486SX25 + 95=big NO! 95 craaawwleedd on my 486dx2/66. Dos 6.22/Win 3.1 for that bad boy.

I already installed Slackware 8.0. Works nicely enough so I can now install DHCP and firewalling. It is slow, of course, with only 8 MB of memory it's hardly going to win the world championships, but it'll be just fine for simple firewalling.