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FOREX 386 motherboard thread

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Reply 21 of 30, by Paadam

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Anonymous Coward wrote:

Is there anyone on here that has this FOREX motherboard?

http://www.ebay.com/itm/Forex-386-Motherboard … V0AAOSwU-pXulJn

I see it pop up all the time. The main reason I haven't bought one yet is the apparent lack of support for 256kb cache. Has anyone ever tried using two 32kx8 tag chips and eight 32kx8 SRAMs to see if it will go to 256k? I know the silkscreen and TH99 both say 128k is max, but for a 1991-1992 board it seems silly to limit it like that.

I got exactly the same board few days ago but without CPU and coprocessor. Will try to find the CPU and test it.

Many 3Dfx and Pentium III-S stuff.
My amibay FS thread: www.amibay.com/showthread.php?88030-Man ... -370-dual)

Reply 22 of 30, by Anonymous Coward

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Thank you, my good man.

"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 23 of 30, by 386_junkie

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I would quite like to see your results also, thanks.

Compaq Systempro; EISA Dual 386 ¦ Compaq Junkiepro; EISA Dual 386 ¦ ALR Powerpro; EISA Dual 386

EISA Graphic Cards ¦ EISA Graphic Card Benchmarks

Reply 24 of 30, by Paadam

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Sadly the place had all the old CPU's taken to gold scrappers so I would like to buy some 386 CPU and coprocessor.

Many 3Dfx and Pentium III-S stuff.
My amibay FS thread: www.amibay.com/showthread.php?88030-Man ... -370-dual)

Reply 25 of 30, by Tommaso72

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dondiego wrote:
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Anonymous Coward wrote:

Is there anyone on here that has this FOREX motherboard?

latest?cb=20150916214043

I have this exact board that I bought off EBay and it came with 33mhz 386dx and 8 megs of RAM. It seems like a really nice board, but I have not been able to use it yet because I am still waiting for an ATX to AT adapter. I also have a TSeng 4000AX to use with it, so I am very excited to see how well it works. It was a little pricey, but it looks brand new and was shipped very professionally. I will let you know how it goes when I start my build, or at least experimenting with it.

Tommaso

Reply 26 of 30, by Robin4

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Anonymous Coward wrote:

Is there anyone on here that has this FOREX motherboard?

http://www.ebay.com/itm/Forex-386-Motherboard … V0AAOSwU-pXulJn

I see it pop up all the time. The main reason I haven't bought one yet is the apparent lack of support for 256kb cache. Has anyone ever tried using two 32kx8 tag chips and eight 32kx8 SRAMs to see if it will go to 256k? I know the silkscreen and TH99 both say 128k is max, but for a 1991-1992 board it seems silly to limit it like that.

I have two of these motherboards.. The last one came with the original manual. Special about it that it supports PGA 386 40Mhz cpus.
That there is only 128K max cache i really dont even bother.. Because 8MB memory is the most i use in these 386 motherboards.

~ At least it can do black and white~

Reply 27 of 30, by 386_junkie

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"Thread resurrection... rise from your grave"... indeed!

Don't mean to hi-jack the thread in the process... only to contribute my own findings with this particular board with a 386DX40... overclocked! 😁

In doing so, I managed to find an Eclipse 100MHz crystal... and to make stable, 256Kb of 20ns SRAM along with 10ns Tags.

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The result... with timings at their lowest, it boot up ok with no hang-ups @ 50MHz.

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The system showed no stability issues and gave off no heat signatures... the heat sink/fan were cool throughout. All the ISA graphics cards I tried yielded the same on 3DBench: -

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Compaq Systempro; EISA Dual 386 ¦ Compaq Junkiepro; EISA Dual 386 ¦ ALR Powerpro; EISA Dual 386

EISA Graphic Cards ¦ EISA Graphic Card Benchmarks

Reply 28 of 30, by Predator99

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Also spotted such board in my collection. Is there any special about this? I only had a 386-16 in spare, so it runs only with Turbo enabled.

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Reply 29 of 30, by Anonymous Coward

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I remember hearing stories of people buying the very late model 386-16s and overclocking the hell out of them, and it appears that's what the previous owner was doing. Notice the board has a 66MHz oscillator, which means the CPU is being overclocked to 33MHz. I heard some people could even push them to 40MHz.

"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 30 of 30, by 386_junkie

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Predator99 wrote:

Also spotted such board in my collection. Is there any special about this? I only had a 386-16 in spare, so it runs only with Turbo enabled.

This is an earlier version of the Forex boards, supporting FSB's of up to at least 40MHz... and are up there with the fastest of 386 boards. Below is another version of the two boards which I've upgraded to a 50MHz FSB. This upgrade would no doubt also be stable with your board (along with the right cache/RAM). The only thing I would maybe change is the CPU... 386DX-40's can still be picked up for peanuts and is one of the best 386 CPU's for overclocking. Having said, I have never over clocked a 386-16, so cannot comment... would be interested to hear of your findings though!

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Anonymous Coward wrote:

The main reason I haven't bought one yet is the apparent lack of support for 256kb cache. Has anyone ever tried using two 32kx8 tag chips and eight 32kx8 SRAMs to see if it will go to 256k? I know the silkscreen and TH99 both say 128k is max, but for a 1991-1992 board it seems silly to limit it like that.

After revisiting the longer of the Forex boards which I used with the Transcomputer thread testing the 386 to 486 module , I found the reason the board only posted with 128Kb cache... was because a single 32K x 8 IC was bad... after replacing it read the full 256Kb. That makes both Forex boards that i've come across support 256Kb.

p.s. The bad IC btw was up top left!

7d20ad596844793.jpg

Compaq Systempro; EISA Dual 386 ¦ Compaq Junkiepro; EISA Dual 386 ¦ ALR Powerpro; EISA Dual 386

EISA Graphic Cards ¦ EISA Graphic Card Benchmarks