Best 386 Motherboard?

Discussion about old PC hardware.

Re: Best 386 Motherboard?

Postby 386_junkie » 2018-3-29 @ 22:06

luckybob wrote:That solution wont work in an IBM. Well, as long as you want to use more than 2 simms. Also the board only supports 1MB simms. If I want to use the 5-16mb range, I have to fill one of these: http://minuszerodegrees.net/5162/cards/ ... s.htm#emea


Your IBM only goes up to 4MB? and what is the FSB of the system? If 20MHz or more, you could get 40ns DRAM to read/write within 1 clock cycle... using 60ns would take 2 clock cycles.


I thought about these ISA bus SIMM extenders before... would they limited to an ISA bus clock divider down to something like 4MHz or would they be remain at the system clock i.e. 16MHz / 20MHz?
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Re: Best 386 Motherboard?

Postby The Serpent Rider » 2018-3-29 @ 22:50

If 20MHz or more, you could get 40ns DRAM to read/write within 1 clock cycle... using 60ns would take 2 clock cycles.

Aren't any memory with 70ns or less is way out of specs for 386 and should work too?
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Re: Best 386 Motherboard?

Postby The Serpent Rider » 2018-5-26 @ 16:41

Soo... acquired the best (tm) motherboard for 386DX I could find. VLB, 256kb Cache, Cyrix 486 support, etc. Well, almost: sockets for 386 CPU/FPU are not soldered, but apparently my version of Dataexpert EXP4349 board is lacking only in that department. All jumpers from online manuals appears to be present. So all I need to do is to add those sockets, right? Or I'm missing something?

Dataexpert EXP4349 - A.jpg

Dataexpert EXP4349 - B.jpg

Dataexpert EXP4349 - C.jpg


Also I'm confused with 3.3v option for CPU without voltage regulator present on the board (jumpers 50, 51, 52).
Last edited by The Serpent Rider on 2018-5-27 @ 02:46, edited 1 time in total.
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Re: Best 386 Motherboard?

Postby feipoa » 2018-5-26 @ 18:41

It probably doesn't have a 3.3 V option without the voltage regulator, so set the jumpers for 5 V.

In all liklihood, soldering in the 386 and FPU sockets will allow you to use 386 CPUs. Aside from the missing voltage regulator, are there many missing components?
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Re: Best 386 Motherboard?

Postby The Serpent Rider » 2018-5-26 @ 19:52

I am not sure where voltage regulator could be installed on this board.
Dataexpert EXP4349 possible VR place.jpg

Maybe here vertically?

Aside from the missing voltage regulator, are there many missing components?

That's what I want to know from the other owners. Jumpers are safe, components seems to be safe too, judging by this pics: https://imgur.com/a/sZPMB
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Re: Best 386 Motherboard?

Postby feipoa » 2018-5-26 @ 20:11

Yes, that is the spot which I would guess the voltage regulator IC goes. What I find further interesting about those photos on imgur is the sticker "This PGA socket is intended for TI486SXL Microprocessor only". I've never seen such a sticker on a motherboard. I'm guessing that certain jumpers were soldered on for the SXL pinout, which has some minor differences with the i486SX pinout, yet, an SX CPU is installed.
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