I need help setting up the RAM on my 486 DX4-100 to get it cracking/searching/whatever

[Sukhoi]

I just got a 486 DX4-100 and I was going to run SETI on it, but it doesn't have enough RAM. Currently it has 8 MB. This is broken up into one 4 MB 72-pin SIMM, and four 1 MB 30-pin SIMMs.

Do you guys have any idea what sizes of 72-pin RAM this board will take, and if I have to put them in, in pairs? I always thought SIMMs needed to be in pairs, but that 72-pin SIMM is all alone (although there is an empty 72-pin SIMM slot next to it).

I currently have an extra two 32 MB 72-pin EDO SIMMs. Is there any way I can use these in my 486 so I can run SETI (SETI requires 32 MB RAM)? I don't want to just stick them in if the board only supports up to 16 MB SIMMS or something like that, and have my SIMMs fried. The computer isn't really used by any people for real work, so it doesn't matter if I end up using only one, or both, of my 32 MB 72-pin SIMMs (if I can even use them at all ).

 

[toph99]

maybe it's a 72pin DIMM?
simms, afaik, MUST be installed in pairs

<edit> proves i don't know a whole lot

 

[Russ]

It's likely that the maximum size would be 64MB per SIMM, so you're fine on that. On a 486 board, a single 72 pin SIMM comprises a bank, four 30 pin SIMM comprise a bank. The only other issue is whether the board will support EDO. If it does, you're set.

There may be a jumper or two that need to be played with to configure the banking for the RAM. On some of the transition boards there were.

Russ, NCNE

 

[Kilowatt]

A true 486 will run just one 72 pin simm.

You might yank out what's in there now, and try both the 32MB simm's together.
If it boots up, and finds all 64MB of ram, you're set.
If not, try it with just one 32MB simm.

Some of the older 486's can't see more then 64MB anyway, but seeing how it's one of the last made IE: DX4-100, it should see more than that.

<EDIT /man Russ is quick on the draw tonight

 

[Rendus]

SIMMs only need to be installed in pairs on Pentiums or higher due to the 64 bit data paths to memory (486 and below were 32 bit, and SIMMs were 32 bit). So you can install single SIMMs in a 486, and even some Pentiums depending on the motherboard (but it's unusual). -edit 2- (SIMMs in this context being 72 pin, and this is from what I remember)

-edit- Oh, and most 486 boards will NOT take EDO SIMMs. They'll take FP usually (Fast Page), or just straight RAM (forget the name). Your board may even require parity, but it's hard to say for certain.

 

[Russ]

Rendus brings up an additional point that I forgot: Parity. While it's unlikely that it requires it, it is possible. A quick way to tell is to look at the SIMM. If they have an even number of chips to a side, they are non-parity. If an odd number they are parity.

Of course, parity memory works just fine in a non-parity board, so even that may not quite answer that one.

Russ, NCNE

 

[Sukhoi]

Thanks for the help guys.

I looked at the 72-pin SIMM, and it has 6 chips on each side for a total of 12 chips, and is thus non-parity. The 30-pin SIMMs have 3 chips on 1 side, so is it possible these are parity? Or, does the even number of chips rule only apply to 72-pin SIMMs?

Now for the big question. If the board does require either normal RAM or Fast Page, what will probably happen if I stick EDO RAM in it? Is there a chance either the EDO RAM or the 486 itself will get fried? Or, will it just not boot correctly?

The mobo has tons of jumpers all over it and I don't have a manual, so there's no way I can change any RAM jumpers.

 

[Sukhoi]

Let me type out the different numbers on the 72-pin SIMM from the 486 incase anyone can identify it as either FP or EDO RAM.

First, on a big sticker covering several chip is the following number:

RMO -OH- OHO796

Also, the serial number on that sticker is:

302920RM0 108000 1

The 0's and O's are almost impossible to tell apart on that sticker, so I may have some of them wrong.

Now, on a smaller sticker cover 1 chip is the following number:

S1M3612P3-6

On the chips themselves it says:

USA N 9617
S413000JDJ
-63

The 9617 number is not all the same though. Some of the chips have 9617, while others have 9613.

On the SIMM itself is the number:

ES1055-003

The SIMM is rev. C. I hope this info is useful.

 

[Russ]

<< The 30-pin SIMMs have 3 chips on 1 side, so is it possible these are parity? >>



This means it is &quot;logic&quot; parity, rather then &quot;true&quot; parity.

Nothing bad will happen if you pop an EDO SIMM in a non-EDO board. It just won't work.

Russ, NCNE

 

[Sukhoi]

<< Nothing bad will happen if you pop an EDO SIMM in a non-EDO board. It just won't work. >>



Cool, I'll try it this evening. I can't wait to see how many hours/WU I get.

 

[Polo]

Go here and try to find your motherboard.
If you find it, you'll be able to configure.

 

[Orange Kid]

most 486's i have encountered will run parity,non-parity or edo ram.
keep in mind that only one kind is best to be used at a time.
i would think that due to the fact that it is already running non-parity, edo should be fine. As russ and others have said if it isn't it just won't show up--no harm no foul.
as a rule from my experience a 486 that will run non parity will run anything, some that run parity will run only that or need a jumper setting to be changed to use other kinds. those that run edo will usually run anything also.
i have noticed that edo in a parity or non-parity system seens to run slower than the non or parity ram.
the mother board or manufactuer name would be a help in determining what you need.
Good luck hope it works

 

[Sukhoi]

I have no idea what manufacturer the mobo is..I can't find the name or model number anywhere. On the chipset (it's the only big black chip other than the processor) it has the name UMC. The following numbers are also on the chipset:

UM8498F
9615-HYT
M21827

The mobo has four 16-bit ISA slots. It also has three slots that seem to be 16-bit ISA slots with a PCI connector stuck at the end. Is this a VESA slot?

Polo, I was looking at your link, and I'm not sure what some of the acronyms on the site are. Does anyone know what VLB and XT stand for?

[edit]After looking through the site some, it seems that VLB is VESA and XT is an 8-bit ISA slot. [/edit]

 

[Sukhoi]

Wow, physically my mobo looks nearly identical to this motherboard, except for the chipset. My mobo seems to have the chipset that this motherboard, although it doesn't look quite the same physically.

I'm only about half through the list on the website, so I may have more matches to come.

[edit]Well, I think I found it. This motherboard seems to be totally identical, including the chipset. I guess this thing only supports fast page RAM though. [/edit]

[edit2]Hmm, here's a version of the mobo I have with fake cache chips: motherboard. When the 486 boots up it does say that it has 256 KB external cache, so can I assume that I have real cache? Thanks for all the help guys.[/edit2]

 

[Orange Kid]

if that is indeed the board you have it will run edo ram.
the (1-64meg FPM DRAM) refers to using a single 64mg simm.(it must be FPM)
the board has a 64 meg limitation. also thow away the 486 chip and find a amd586 or pentium chip as the board supports it.
486 chips have 17pins per side, that socket has 19 so will take a 586 or pentium chip. i think 133mhz is max. just put a HD in a comp with the same looking type of board!!,p133. don't remember the specs,was a home brew,but do remember the board.
the short slots are vesa, a card here will use both the isa part and vesa part. as you have probable noticed there are no ide or floppy headers. a controler card must be used. hope you have one as the are getting tough to find.

 

[Viztech]

It may be interesting if that board will identify a single strip of RAM as either EDO or FPM. You know, the message that says &quot;EDO at line none,0,1 etc.&quot;
Seems like the AMI and Award BIOS mobos will display the message at boot, and the Phoenix BIOS you need to go into setup to find that info.
I end up working with a lot of older machines, and would LOVE to have a 486 board that will identify a single EDO SIMM. It would be extremely useful to me. Seems like I had a late Gateway-Intel-Phoenix PCI bus board that had that feature once.

VLB stands for VESA Local Bus, a precursor to PCI bus.

viz

 

[ZF3361]

Sukhoi

Try this site make a note of the bios on boot up. You
should then be able to find maker and model from this site.

 

[Joe O]

Sukhoi, ZF3361 beat me to the punch. Copy down the string that appears at bootup usually lower left but sometimes upper left. Sometimes the Video card puts out a string as well. If you have a printer attached sometimes printscreen key will work. It won't eject the page, you'll have to do that manually. Sometimes pause key will work. Sometimes you just have to boot many times. You could also use ctbios to capture the download information if there is a running floppy on the machine. Download CTBIOS here

When you have the Bios string post it here and I'll look it up for you.(If someone else doesn't beat me to it).

 

[Sukhoi]

Orange Kid, I'm nearly 100% sure that's the board I have (mobo for anyone who didn't see the link in my other post). I was actually holding the 486 with the case off in my lap when I was lookng at the pic. There might be 1 or 2 capacitors in a different place, but other than that it seems like the same motherboard. I do have a controller card. I got the whole system, including a 14&quot; or so SVGA monitor, keyboard, and mouse for $14 at the Goodwill store. I'll have to decide if I switch processors. I can probably upgrade to either a 83 MHz Pentium OverDrive processor, or a K5 133 MHz. The website says it's socket 3, so I don't think it'll take a normal Pentium chip since they're socket 5.

I have to go to bed pretty soon, but I'll work on the system when I get home from school tomorrow. First I'm gonna take out all the RAM and put in one of my 32 MB 72-pin EDO SIMMs and see if it works. Then I'll put in the other and see if that one works.

The board does seem to have a lot of the jumper specifications listed on the board, so I might be able to change processors fairly easily.

ZF3361 and Joe O, I'll try to copy the BIOS code down when I get home tomorrow too.

Oh, another question. If I upgrade to say a K5 133, will I need to get a new heatsink/fan combo? If so, where the heck could I find one cheap?

 

[LeBlatt]

- In France we had a fair amount of mobos with fake-cache in 95. [edit]I confess I unknowingly sold a few. [edit] They were PC-Chips chipset based, so if you have an UMC I'd guess it has cache. On the picture you linked there are only 4 cache chips plus 1 parity, and 4 more are empty. looks like it only has 128K cache. If yours has 8+1 its 256K.

- All 486 mobos from mid-95 took EDO simms.

- On many dual memory boards (4 x 8bits + 1 or 2 x 32 bits), 1 bank was shared by 1 32 bit slot and the 4 8 bit slots so your options were :
-- 4x8 bits (all same)
-- 4x8 bits + 1x32 bits (not any, but the non-shared one)
-- 1x32 bits
-- 2x32 bits

- in those times I never used sticks over 16MB, but I once had 1x16MB + 1x8MB and it worked ok.

- any board that takes EDO will take FPM, but not the opposite.

- see another 486 memory thread here.

 

[Sukhoi]

Ok, I finally got time to put in my 32 MB EDO SIMMs. First I pulled all the RAM out of the system. Then I put in both of my 72-pin 32 MB EDO SIMMs. The system booted, but it only picked up 32 MB out of the 64 MB. I then took out SIMM #2, and it correctly picks up 32 MB when I boot up. I guess SIMM slot #2 isn't currently working. I'm pretty sure that PC Chips actually made the motherboard, so I'm going to look around on their site and see if they have any jumper listings. Maybe I need to change a jumper to get both SIMM slots to work.

Though I have noticed Win95A actually seems to open windows and such slightly slower with the extra RAM. Am I insane, or is the RAM possibly not being seen correctly by the motherboard, and thus running slower?

Oh, I noticed something very interesting today when I was looking at the mobo. Assuming I read the jumper description charts correctly, this thing seems to be running 3x33 rather than 4x25. Is there any free software that will test this for me?

 

[Rendus]

Sounds like the board may not be able to cache all 32MB of RAM. Also, 32MB may be the limit the board can take, not sure.

 

[LeBlatt]

<< thing seems to be running 3x33 rather than 4x25 >>



Correct, a DX4-100 runs at 3x33. The '4' in DX4 is just intel's maketing imagination. Same goes for AMD's DX4-120 which are 3x40.

 

[Sukhoi]

Oh, cool. I always thought the DX4 was 4x25.

If I can figure out all the jumpers I'd have to set, should it be possible to run 2x50 or something like that? I know my RAM will do 66 MHz fine.