VOGONS


Reply 20 of 29, by pshipkov

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Funny, somebody just gave me an old 386 mobo that was collecting dust in his house.
It is exactly the same motherboard as Keropi's.
Can you confirm that its cache actually works ?
Thanks.

Reply 21 of 29, by Scali

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keropi wrote:

It occured to me, Cyrix M6 is a 486 cpu, right? If yes then it's just weird having a 386 getting detected as 486...

Back in those days, CPU detection wasn't an exact science.
It wasn't until the Pentium CPU that the CPUID instruction was included, where you can actually query the CPU for its description and properties.
Before that, CPUs were detected by various tricks, such as setting certain bits in the flags register, and then reading them back to see which bits would 'stick'.
So it's not that strange to have some false positives.

http://scalibq.wordpress.com/just-keeping-it- … ro-programming/

Reply 22 of 29, by Thermalwrong

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pshipkov wrote:
Funny, somebody just gave me an old 386 mobo that was collecting dust in his house. It is exactly the same motherboard as Keropi […]
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Funny, somebody just gave me an old 386 mobo that was collecting dust in his house.
It is exactly the same motherboard as Keropi's.
Can you confirm that its cache actually works ?
Thanks.

I used CacheChk and that showed 128KB of fast memory and the rest as slow memory, so the cache definitely works.

Reply 23 of 29, by pshipkov

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So strange.
I am looking at Keropi's screenshots and despite the fact that the mobo reports 128Kb of installed cache, the tests indicate that there is actually no cache.

I tried bunch of different SRAM chips to make sure i am not hitting faulty ones, but no luck at getting the mobo to actually use the cache.
Can you clarify what what chips you have installed on your mobo ?
Thanks.

Reply 24 of 29, by Thermalwrong

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My board has Hitachi HM62832HP 25ns 32Kx8 SRAM chips and a Mitsubishi M5M5178BP-15 8Kx8 TAG chip. Keropi's board has a w2465ak-15 as the TAG SRAM, which is also an 8Kx8 chip. I didn't know that it used a smaller TAG cache 😀

The pinouts are different enough between the 32kx8 chips and 8kx8 chips that a 32Kx8 chip can't be used in place of the 8Kx8 TAG SRAM. It won't short, I think, but it won't work.

Here's cachechk and speedsys results, not particularly fast, but the cache is definitely working.

 CACHECHK v4 2/7/96  Copyright (c) 1995 by Ray Van Tassle. (-h for help)
CMOS reports: conv_mem= 640K, ext_mem= 15,360K, Total RAM= 16,000K
Clocked at 386 39.6 MHz
Reading from memory.
MegaByte#: --------- Memory Access Block sizes (KB)-----
1 2 4 8 16 32 64 128 256 512 1024 2048 4096 <-- KB
0: 41 41 41 41 41 41 41 41 113 113 -- -- -- æs/KB
1: 41 41 41 41 41 41 41 41 113 113 113 113 113 æs/KB
2 3 4 5 6 7 8 9 10 11 12 13 14 15 <--- same as above.

Extra tests----
Wrt 34 34 34 34 34 34 36 34 34 34 34 34 34<-Write mem
This machine seems to have one cache!? [read]
!! cache is 128KB -- 26.8 MB/s 39.1 ns/byte (276%) 5.9 clks
Main memory speed -- 9.7 MB/s 108.0 ns/byte (100%) [read] 16.3 clks
Effective RAM access time (read ) is 216ns (a RAM bank is 2 bytes wide).
Effective RAM access time (write) is 65ns (a RAM bank is 2 bytes wide).
Clocked at 386 39.6 MHz. Cache ENABLED.
Options: -t0 -qq

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Reply 26 of 29, by GrooBR

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Hi People !
I'm from Brazil and have 6 boards of this same model but incomplete ones. It lacks cache, BIOS and CPU. I want to buy some i386DX-33 QFP132 from China.
Best of all, I have some manuals of this board and in a few days I'll scan it and made it available here !!

Reply 27 of 29, by Mut

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GrooBR wrote:

Hi People !
I'm from Brazil and have 6 boards of this same model but incomplete ones. It lacks cache, BIOS and CPU. I want to buy some i386DX-33 QFP132 from China.
Best of all, I have some manuals of this board and in a few days I'll scan it and made it available here !!

Hi GooBR!,

I have bought a couple of those same strange boards on mercadolivre.

Looks like someone have desoldered battery, CPU and removed bios and cache before putting then on storage.

I have a old 386 removed from a dead board to solder and test these boards.

Reply 28 of 29, by Thermalwrong

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GrooBR wrote:

Hi People !
I'm from Brazil and have 6 boards of this same model but incomplete ones. It lacks cache, BIOS and CPU. I want to buy some i386DX-33 QFP132 from China.
Best of all, I have some manuals of this board and in a few days I'll scan it and made it available here !!

That would be excellent if you can scan it. There are some things I still can't figure out on this board, so it would be really useful to have a read of the manual 😀