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First post, by PDXTony

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Hello fellow awesome people!

I'm beginning a 486 build and would greatly appreciate your help.
For fun, I'd like to put the maximum capacity of 30-pin SIMM memory this motherboard supports, which is 128mb.

The motherboard is a BEK-V409, detailed on this page:
https://stason.org/TULARC/pc/motherboards/B/B … 6-BEK-V409.html

I've Google'd a bit beyond that and found all sites referencing this motherboard indicate a maximum about of 128mb using two sets of four 30-pin SIMMs at 128MB (8 sticks of 16M x 9).

With that said, mind helping me choose what has the greatest chance of being compatible?

Also, some specific questions if I may please:
Does the '16M x 9' spec mean that I must choose 9 chip modules? Or am I misunderstanding that?
What about voltage and latency speeds?
Anyone know if this motherboard supports parity or only non-parity?

Thank you very much in advance!

Tony

Reply 1 of 14, by jakethompson1

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Just so you're aware, no more than the first 32MB (or at most 64MB if write-through or always dirty write-back) of RAM would be cached, and Windows allocates from the top down, so the uncached memory would be used first. In addition, if you're using an SVGA VLB card with a linear framebuffer, you would want to make sure it can map it very high in memory and that the board and card is actually wired with address lines to map it beyond 64MB. More on that here: https://www.xfree86.org/3.3.6/cirrus5.html#5

Personally, I would use a PCI 486 system, or a later era VLB board like an SiS 471-based one, if I wanted to max out memory that high. Plus, 128MB in 72-pin will be much cheaper than 30-pin, since most of what you're paying for is shipping and the labor of testing by the piece at this point.

16Mx9 is referring to 8 data bits and one parity bit. It doesn't mean it needs to be 9-chip memory. The difference between 9-chip and 3-chip has something to do with how it is refreshed, I believe. You can search mkarcher's posting history for a detailed description of this as he is very good at explaining such things, or he or someone might jump in. IIRC anything 486-era supports 3-chip.

It would surely be 5 volts FPM; don't think you can find 30-pin in anything else easily, and you won't find faster than 60 nanoseconds without jumping through hoops.

You can look in the BIOS for an option to disable parity check. If you don't have it working yet, you could try finding the BIOS image or reading it, and booting it in PCem. It could be hidden, which would be annoying. Ideally it's already off by default.

Reply 2 of 14, by PDXTony

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Thank you very much for the detailed information!
I'm going to start by trying: 64MB (4 X 16MB) FPM PARITY 60NS SIMM 30-PIN 5V 16X9 MEMORY RAM
I didn't know about the memory capacity to cache ratio. The motherboard has 256k of cache and I plan to run it in write-through mode.
I'll report back here with some results!

Reply 3 of 14, by maxtherabbit

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I'd like to kindly direct you to the listing for your board on The Ultimate Retro

https://www.ultimateretro.net/en/motherboards/1041

Please stop linking to stason. UR is a community project run by guys from this very forum

Reply 5 of 14, by maxtherabbit

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PDXTony wrote on 2022-06-29, 19:39:
maxtherabbit wrote on 2022-06-29, 19:37:

Please stop linking to stason.

OK now I am curious why it matters. Did Stason do something bad?

Not really, just don't loike em simple as

Reply 6 of 14, by TheMobRules

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maxtherabbit wrote on 2022-06-29, 19:45:
PDXTony wrote on 2022-06-29, 19:39:
maxtherabbit wrote on 2022-06-29, 19:37:

Please stop linking to stason.

OK now I am curious why it matters. Did Stason do something bad?

Not really, just don't loike em simple as

I think the "Don't let your bike seat ruin your SEX LIFE" book ad is bad enough to avoid Stason like the plague 😛

Reply 7 of 14, by PDXTony

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TheMobRules wrote on 2022-06-29, 20:00:
maxtherabbit wrote on 2022-06-29, 19:45:
PDXTony wrote on 2022-06-29, 19:39:

OK now I am curious why it matters. Did Stason do something bad?

Not really, just don't loike em simple as

I think the "Don't let your bike seat ruin your SEX LIFE" book ad is bad enough to avoid Stason like the plague 😛

I think those ads base themselves off your browsing history, good sir... 😉

Reply 8 of 14, by TheMobRules

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PDXTony wrote on 2022-06-29, 21:51:
TheMobRules wrote on 2022-06-29, 20:00:
maxtherabbit wrote on 2022-06-29, 19:45:

Not really, just don't loike em simple as

I think the "Don't let your bike seat ruin your SEX LIFE" book ad is bad enough to avoid Stason like the plague 😛

I think those ads base themselves off your browsing history, good sir... 😉

Nope, my ad blocker prevents that 😉 , those are fixed ads of books written by Mr. Stason himself. Just take a look at the homepage, he has all kinds of weird stuff besides the "PC Info" section which, if I'm not mistaken, he lifted entirely from "Total Hardware 1999". That's a very good reason to use Ultimate Retro (or fall back to TH99 if necessary).

Reply 9 of 14, by maxtherabbit

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PDXTony wrote on 2022-06-29, 21:51:
TheMobRules wrote on 2022-06-29, 20:00:
maxtherabbit wrote on 2022-06-29, 19:45:

Not really, just don't loike em simple as

I think the "Don't let your bike seat ruin your SEX LIFE" book ad is bad enough to avoid Stason like the plague 😛

I think those ads base themselves off your browsing history, good sir... 😉

They don't we all see that same bullshit

Reply 10 of 14, by PDXTony

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maxtherabbit wrote on 2022-06-29, 19:45:
PDXTony wrote on 2022-06-29, 19:39:
maxtherabbit wrote on 2022-06-29, 19:37:

Please stop linking to stason.

OK now I am curious why it matters. Did Stason do something bad?

Not really, just don't loike em simple as

😀 OK ok ok - got it - AND...I even contributed some pictures and a BIOS dump to: https://www.ultimateretro.net/en/motherboards/1041

Reply 11 of 14, by jakethompson1

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PDXTony wrote on 2022-07-03, 01:56:
maxtherabbit wrote on 2022-06-29, 19:45:
PDXTony wrote on 2022-06-29, 19:39:

OK now I am curious why it matters. Did Stason do something bad?

Not really, just don't loike em simple as

😀 OK ok ok - got it - AND...I even contributed some pictures and a BIOS dump to: https://www.ultimateretro.net/en/motherboards/1041

Have any luck with the RAM?
I believe the UM491 does not support robbing a bit from the tag RAM to use as the dirty RAM. So your cacheable area is indeed 64MB, and likely "always dirty" as there is no dirty RAM that I see. You can use CACHECHK once you get it going to see. On my 486DX2/80 UM491 board, I get 16 us/KB for L1, 20 us/KB for L2, and 37 us/KB for RAM.

Reply 12 of 14, by PDXTony

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jakethompson1 wrote on 2022-07-03, 02:01:
PDXTony wrote on 2022-07-03, 01:56:
maxtherabbit wrote on 2022-06-29, 19:45:

Not really, just don't loike em simple as

😀 OK ok ok - got it - AND...I even contributed some pictures and a BIOS dump to: https://www.ultimateretro.net/en/motherboards/1041

Have any luck with the RAM?
I believe the UM491 does not support robbing a bit from the tag RAM to use as the dirty RAM. So your cacheable area is indeed 64MB, and likely "always dirty" as there is no dirty RAM that I see. You can use CACHECHK once you get it going to see. On my 486DX2/80 UM491 board, I get 16 us/KB for L1, 20 us/KB for L2, and 37 us/KB for RAM.

Hey! Yes, the 64mb of memory I ordered works perfectly in the board. Tonight I plan on running CACHECHK and a few other utilities to ensure it's stable.

Reply 13 of 14, by rasz_pl

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There is almost nothing(*) that runs great on 486 and requires more than 16MB of ram, but there is plenty of things that go wrong with more like already mentioned caching and linear VESA buffer access.

* linux proxy/local file server in 1994?