VOGONS


First post, by m0rd

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Hi, i just got this ps/2 and wondering a few things. first it has this 386 upgrade that doesnt seem to be the intel or kingston. Any ideas what the jumper switch maybe for?? It was a telecoms (telstra) computer.
Can these ps/2 work with a isa ide cards from later computer? Ive tried a prime 2c card but cant get system to see the hard drive.
I have got a xtide coming but would like to try getting ide hard drive running so i can use it a bit 🤣

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Reply 1 of 18, by mkarcher

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First thing to be aware of (maybe you are) is that there are two different machine types with the label "PS/2 model 30". You got the later one, based on a 286 board, called "model 30/286" to distinguish it from the classic "model 30". I'm more acquainted with the classic one. The classic one has a proprietary on-board hard drive interface that gets completely disabled if no hard drive is plugged into it. The same should be true about the model 30/286, so physical conflicts will most likely not be the cause for the Prime 2C not to work as it should.

At least on the PS/2 model 30 (non-286), the hard drive command set and interface type is something you don't find on any other computer (except the PS/2 model 25). Non-PS/2 drives are not supported by the on-board BIOS. The PS/2 model 30/286 still uses a proprietary hard drive system which is neither hardware nor software compatible to IDE, so I'm not surprised that the mainboard BIOS does not support IDE drives. Using an add-on ROM with IDE support (e.g. the XT-IDE) should add IDE support to the machine.

Reply 2 of 18, by m0rd

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just a few benchmark result from phils computerlab. SysInfo 8 = 17.2, sysspeed 4.78 =4.15. ran cachecheck and seems to have 64kb, did all ibm ps/2 model 30 286 have this cache or would it be part of the 386 upgrade board??

Reply 3 of 18, by luckybob

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Yea, the hard drive is intentionally proprietary. You also can't just toss in an adapter either. It needs to have special roms to work. These hard drives are reliably horrible.

The cache is part of the upgrade, the chips at the top center are likely the L2 cache. the stand out number is the "-25" when you see -### like that on chips, it's quite often a speed designation.

It is a mistake to think you can solve any major problems just with potatoes.

Reply 5 of 18, by m0rd

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ye bob i cant pm yet. It came with the system which i thought would had been either a 8086 or 286 but this what came in it and im stoked as i can run eob3 and 386 stuff. dam looks like ill have to wait till the xtide gets here. i modded a gotek for floppy and added a battery to the dallas chip so just gota sort out hard drive now. i plan to use a aztec crystal card for sb pro 2.0 and either a tseng labs et400ax or a s3 801, any idea which will be the faster/most compatible???

Reply 6 of 18, by mkarcher

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If you already have a ET4000AX, and don't have to buy at the current inflated prices, I would definitely use that card. For DOS gaming, ISA write performance is the only thing that counts, and in your system, an ET4000 card should never be the performance bottleneck. S3 has the advantage of Windows acelleration, so if you plan to use windows primarily, the S3 card might be a better idea.

Reply 8 of 18, by BitWrangler

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Looks similar to the Intel MakeIt 386 board, but I haven't seen one of them close enough to say how similar, other than it's a big board that perches on the 286 socket.

Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.

Reply 9 of 18, by luckybob

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I personally went with SCSI on my model 25. (Same mother board) with a Soundblaster. I have a scsi to ethernet adapter as you only get 2 slots on a 25.

Scsi makes sense for me, as I can add a CD, and I can use it for odd things, like ethernet.

The onboard video is perfect adequate for a 8088/286 machine.

It is a mistake to think you can solve any major problems just with potatoes.

Reply 10 of 18, by Anonymous Coward

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It's not made by IBM or Intel. They would have made it obvious.

IT has "TE" stamped all over it, including "TE Rev H" on the bottom. I would guess TE might be an acronym for the manufacturer or model name.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 11 of 18, by BitWrangler

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Yah I was suggesting it more as a knockoff rather than Intel would stick an AMD CPU on one of their products 🤣

Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.

Reply 12 of 18, by m0rd

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well the machine came from a phone company we had here in australia called Telecom they are now known as telstra. I guess it possible ibm did this board locally for telecom?? as telecom may have needed 1000's of these for the business???
and it seems it has 64kb cache??? did the standard ps/2 286 have any cache and does other upgrade boards have cache?? Can anyone tell by looking at the chips on it how much cache it should have??? maybe that what the jumper switch configures???? Yes back in lte 80's & 90's australia did have local electronic manufactures, i think one was called Leading edge tech and another was Legend brang i think

Reply 13 of 18, by BitWrangler

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This PC Mag has some turbo board reviews in, but none of them look similar, might be worth a read though to see common features and problems to get a feel for it... https://books.google.ca/books?id=jE2OlZ9PkrkC … epage&q&f=false Page 243.... There might be some advertisements of similar products also. Though I'm thinking that with an AMD 386, it might have been a later product... or maybe originally had intel CPU until the cheaper AMD came along.

Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.

Reply 15 of 18, by Anonymous Coward

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External cache on earlier 286->386 upgrades was fairly common. Later modules tended to have CPUs with their own internal cache instead.

"Will the highways on the internets become more few?" -Gee Dubya
V'Ger XT|Upgraded AT|Ultimate 386|Super VL/EISA 486|SMP VL/EISA Pentium

Reply 16 of 18, by mkarcher

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m0rd wrote on 2021-08-10, 02:33:

and it seems it has 64kb cache??? did the standard ps/2 286 have any cache and does other upgrade boards have cache??

I don't know about other upgrade boards, but the original PS/2 Model 30/286 (which is an entry-level PS/2 placed even below the Model 50) definitely didn't have memory cache. Possibly it didn't even need memory cache because memory was fast enough. In case of the upgrade module, consider that the 386SX on that module is clocked considerably faster than the original 286, so it also wants to access memory faster. The x86 architecture is quite dependent on memory performance, so slowing down the memory access of the upgrade module to the original PS/2 Model 30/286 memory speed would significantly reduce memory performance. Cache is needed to make an upgrade like this work.

Instead of having cache on the board, one could also just go 486, using one of those 16-bit bus 486 processors (Cyrix 486SLC (or it's second source SGS Thompson 486SLC) or IBM 486SLC (which is an entirely different chip)), which have integrated cache.

m0rd wrote on 2021-08-10, 02:33:

Can anyone tell by looking at the chips on it how much cache it should have???

The cache on your module consists of the fast CMOS SRAM chips on the board: 3 chips MB8298-25, and one chip labelled ATT7C174P. The MB8298-25 chips make up for 32 kilo addresses with 8 bits each. Two of these chips are used to form 32 kilo addresses of 16 bits (to match the 386SX bus width). 32K addresses that contain 16 bits is the same amount of data as 64K addresses that contain 8 bits (a byte), so that is 64K of cache RAM. The ATT7C174P chip is a very interesting chip: It is used as tag RAM (taking note what address is actually in cache), and does not only contain the cache, but it also integrates the comparator that tells the board whether the address the processor is trying to access right now is in the cache or not. This chip is for up to 8K cache lines, so the line size is 8 bytes or bigger. On a 386SX board, a line size of 4 words of 2 bytes each sounds likely. The last chip, the third MB8297-25 is most likely contains valid (and dirty?) bits telling which words of a cache line contain data, and which words are unknown.

I'm very sure there is no way to upgrade cache on that board. At those time, cache controllers were not designed to be flexible, but just to work for the one use case they are designed for. So this upgrade has 64K cache, and there is very likely no way to change that using (just) replacement ICs.

Last edited by mkarcher on 2021-08-11, 10:24. Edited 1 time in total.

Reply 17 of 18, by luckybob

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To be frank, 64k is more than plenty for a suped up 286. Even baseline 386 boards topped out at 256k and the performance difference between 64 & 256k is marginal at best. Keep in mind, this is for the software that makes sense on a 2/3-86.

I'd wager the buyers of these upgrades were more interested in getting a 386 instruction set than raw speed.

It is a mistake to think you can solve any major problems just with potatoes.