Sorry one. Last thing, also not clear on Dram to get, I understand its 30pin, 70ns FPB simms is that what I search for because I can't find any.

You seem to have confusing sources. The board in that computer only provides a single bank of cache. The cache sockets have 28 pins. The biggest cache chips that fit into 28-pin sockets are 32kx8 chips. There are 64kx8 and 128kx8 chips, but they come in 32-pin cases, not 28-pin cases. A single bank of 32kx8 cache chips provides 128KB of cache, and that is the maximum supported in that board.

This board uses an 8-bit wide tag, and a separate dirty bit (called "ALT" for "altered"). The separate ALT bit was common on 386 boards, but most newer 486 boards split the tag ram into 7 tag and 1 dirty bit. Your board does not do that. This is good news and bad news at the same time: 8 tag bits make up for the double amount of memory being cachable. But it means you "waste" 7 of 8 bits in the chip used for the ALT RAM. The sizes you quote seem inconsistent. According to the schematics in the manual, the TAG RAM and the ALT RAM are addressed in the same way, so it makes no sense to specify different sizes for the two chips. Generally, single-bank caches need a tag RAM with a quarter of the depth of the data RAMs. So for 32k x 8 data RAMs, you need 8k x 8 TAG/ALT RAMs. The schematic shows that the TAG/ALT sockets are wired in a way that bigger RAMs do not matter. It will work with 6 chips of 32k x 8 as well.

The memory type you quote has a typo. It's not "FPB" simms, it's "FPM" simms. You don't need to get SIMMs to get started, though. According to the ebay offer, the board comes with 8MB RAM, which is 8 sticks of 1MB each. This is enough to get started with a 486 system. If you want / need more RAM, you need to get 4MB 30-pin SIMMs. It doesn't matter if they are faster than 70ns, so 60ns would work too. Furthermore, all 4MB 30-pin SIMMs are FPM, so you don't have to check the offers for specifying "FPM" (fast page mode). I get a lot of hits on ebay searching for "4MB 30 pin". All of those offers are good for your board, if you exclude the sets "4*1MB = 4MB". You already got enough 1MB modules, so no need to buy these sets. Be advised that those boards have banks of four modules. So the next step from 8MB is 20MB (4*1MB + 4*4MB). Just getting one or two 4MB modules will not work. Boards of that age often require a specific order of the modules, so you either check the manual, or you need to test whether the 20MB configuration needs the 4MB*4 on the 1MB*4 block inserted first.

Thanks for such a informative response. Great stuff.

So I can add 128kbl2 cache only with 6x 32kb x8 chips? What spec or serial numbers do I look for?
You mention 8 sticks of 1mb but photo is showing 4x sticks.. Which I assume are 2mb 30 pinn simms?

The other four slots I assumed would need 2mb so 16mb of ram?

Do you have any advice on internal gfx card? What ram chip I need to go 1mb.

Finally is that right manual for mobo or did I mess that up too.

Thanks again

Cant find the l2 cache ram. M I searching the right codes from above?

One thing I don't get is for example to me 44256 is 256kb.. So if I had 8 that's 2.mb? Why is it people say 8, 44256 is 1mb.. How does it work out

Would this work for L2 cache? 6 of them?

https://www.ebay.co.uk/itm/222523693019

No, this will not work - these are for BIOS storage. You need something like this: https://monotech.fwscart.com/Cache_SRAM_for_4 … 4_20624218.aspx

WazMeister wrote on 2021-03-06, 14:56:

Cant find the l2 cache ram. M I searching the right codes from above?

One thing I don't get is for example to me 44256 is 256kb.. So if I had 8 that's 2.mb? Why is it people say 8, 44256 is 1mb.. How does it work out

A 44256 DRAM module is arranged as 256k (rows) by 4 bits (per row), that's a total of (256 x 4) 1024 kilobits per module.

There are 8 bits in a byte, so it therefore has an addressable capacity of (1024 / 8 ) 128 kilobytes per chip.

You therefore need 8 of those 256Kx4 chips to make up 1024 kilobytes, or 1 megabyte. It's a very common size of DRAM for early ISA VGA cards to use, as well as systems like the Amiga.

So, got machine. It has 1mb vesa onboard CL gfx card, it has a 486 66, seems jumpers were set wrong to 50.. Most tests showing 486 50 but changed as per manual and now syschk shows 486 66.
Topbench some reason gets very low scare and shows system as a 386 with a 212kb gfx card? It also crashes on scanning system at Cpu cycle.

Tried to get a CF to IDE to work on it as a slave (only 1 ide port for hdd). Initially. It showed up but would not format.. It did create a partition. I then randomly got a no fixed drive error and not even thr hdd will boot.... Tried seating everything again but not working... Shame! What now

Hi, just to. Check.

Is this the L2 cache I need, 6 off as I have 6 slots
k/itm/2-x-M5M5256DP-70LL-Mitsubishi-SRAM-28-pin-32Kx8-NEW-PARTS-UKINSTOCK-2-CHIPS-/224370258883?_trksid=p2349624.m46890.l49292

Sorry working link here
https://www.ebay.co.uk/itm/2-x-M5M5256DP-70LL … 4.m46890.l49292

No, this is TSOP package and You need DIP.

You'll need 20ns or faster rated parts, 70ns will be much too slow to work as cache. 15ns ought to work without any trouble.

mkarcher wrote on 2021-03-04, 22:57:

You seem to have confusing sources. The board in that computer only provides a single bank of cache. The cache sockets have 28 pins. The biggest cache chips that fit into 28-pin sockets are 32kx8 chips. There are 64kx8 and 128kx8 chips, but they come in 32-pin cases, not 28-pin cases. A single bank of 32kx8 cache chips provides 128KB of cache, and that is the maximum supported in that board.

This board uses an 8-bit wide tag, and a separate dirty bit (called "ALT" for "altered"). The separate ALT bit was common on 386 boards, but most newer 486 boards split the tag ram into 7 tag and 1 dirty bit. Your board does not do that. This is good news and bad news at the same time: 8 tag bits make up for the double amount of memory being cachable. But it means you "waste" 7 of 8 bits in the chip used for the ALT RAM. The sizes you quote seem inconsistent. According to the schematics in the manual, the TAG RAM and the ALT RAM are addressed in the same way, so it makes no sense to specify different sizes for the two chips. Generally, single-bank caches need a tag RAM with a quarter of the depth of the data RAMs. So for 32k x 8 data RAMs, you need 8k x 8 TAG/ALT RAMs. The schematic shows that the TAG/ALT sockets are wired in a way that bigger RAMs do not matter. It will work with 6 chips of 32k x 8 as well.

The memory type you quote has a typo. It's not "FPB" simms, it's "FPM" simms. You don't need to get SIMMs to get started, though. According to the ebay offer, the board comes with 8MB RAM, which is 8 sticks of 1MB each. This is enough to get started with a 486 system. If you want / need more RAM, you need to get 4MB 30-pin SIMMs. It doesn't matter if they are faster than 70ns, so 60ns would work too. Furthermore, all 4MB 30-pin SIMMs are FPM, so you don't have to check the offers for specifying "FPM" (fast page mode). I get a lot of hits on ebay searching for "4MB 30 pin". All of those offers are good for your board, if you exclude the sets "4*1MB = 4MB". You already got enough 1MB modules, so no need to buy these sets. Be advised that those boards have banks of four modules. So the next step from 8MB is 20MB (4*1MB + 4*4MB). Just getting one or two 4MB modules will not work. Boards of that age often require a specific order of the modules, so you either check the manual, or you need to test whether the 20MB configuration needs the 4MB*4 on the 1MB*4 block inserted first.

Can you explain the Dram a bit more please.

The board has 8x slots with 4x having ram. I assume its 2mb on each stick? So do I not just buy another 4x 2mb and go for 16mb ram?
Where did you get 1mb from? If it was 1mb each it be 4mb and not 8mb in system.

Many thanks

WazMeister wrote on 2021-03-15, 10:56:

Can you explain the Dram a bit more please. […]
Show full quote

Can you explain the Dram a bit more please.

The board has 8x slots with 4x having ram. I assume its 2mb on each stick? So do I not just buy another 4x 2mb and go for 16mb ram?
Where did you get 1mb from? If it was 1mb each it be 4mb and not 8mb in system.

Many thanks

The picture doesn't match the description. There are no common 2MB 30-pin RAM modules, and nearly no 486 mainboard supports such modules. If the seller offers the board with 8MB of RAM, the board will be sold with all 8 slots filled with 1MB modules. If you need more than 8MB, you need to replace four of the eight 1MB modules by 4MB modules, which will yield 20MB of RAM.

Sorry, it just don't make sense.
There are 8x slots for ram sticks, so far only 4 are used with ram sticks. The pc has a total of 8mb ram....

Unfortunately, this may not be true - there may be 4 modules of 4 MB on the board, of which BIOS can only see half, i.e. 4x2 MB, which gives the 8 MB of visible RAM. SIMM memory modules with a capacity of 2 MB were not produced, if I can remember.

I recently purchased a similar machine, a Samsung Deskmaster 486slc/25. The case looks exactly the same as yours, different mobo though (mine has the soldered in 486slc chip). Mine had a 120MB hard drive which was completely full, <10KB free space. I was able to successfully set up a 2GB CF card and transferred all of the original HD installation (DOS 6.22/Win 3.1). I used a Startech CF-IDE adapter, 2GB Innodisc Industrial CF card, and installed using On Track Disk Manager with BIOS set to Type 1. The single IDE channel on the mobo has a 4x CDR as slave and the CF (formerly HD) as master. One of the best things about mine is that it came with a SB Pro 2 CT1600 installed., which works great. I have ordered a HardMPU to use in this machine (could not seem to get a PCMIDI). Onboard video is a Western Digital chip, 512MB. I would like to look into upgrades, unfortunately I have had no luck finding a manual for the 486slc/25. I did find your manual when searching.

WazMeister wrote on 2021-03-19, 23:53:

Sorry, it just don't make sense.
There are 8x slots for ram sticks, so far only 4 are used with ram sticks. The pc has a total of 8mb ram....

I know. The picture shows a board with either 4MB or 16MB of RAM installed.

It might be that Ydee is right, and there are 16MB installed in that board, but the BIOS is unable to cope with more than 8MB, but this would be very surprising for SiS461-based boards. They are new enough to properly support 16MB of main memory. Thus I supposed the photo of the board was not taken with all of the memory modules installed that were installed when the BIOS photo was taken.

The chipset supports 8MB banks (2M x 36), as shown on page 3-20. That would be configuration "11000", but there are no (common) 30-pin simms having 2M x 9 (four of them making 2M x 36). It's possible that the generic chipset initialization code in the BIOS detected 4M x 36 as 2M x 36, because it is partially broken, though.

Photos is mine.

It has 8mb ram.
That's what's reported y system. So are we saying that it's more than 8mb or less?

Still confused, sorry