• Please review our updated Terms and Rules here

AMD 386-40 In 486 board?

No it is not possible at all.

You can have a 486 in a 386 board w/ special upgrade chips, but there's no way to stick a 386 in a 486 board. There *are* lowend 486 chips that are almost identical to 386 chips, but it's debatable whether you can really call them a 386 or a 486 - those would be the 486SLC and such (if memory serves).

Anyway a typical socketed 386 chip is most definitely NOT pin-compatible with a 486 chip, and 486 chips actually have five different sockets, so keep that in mind as well (486, 1, 2, 3, 6).

A 386DX40 is designed for a socketed 386 board, so you'll have to find one of those if you want to run it.

Why is this question coming up, anyway? Do you have a 386 and no boards, but a bunch of 486 boards?
 
Raven said:
Why is this question coming up, anyway? Do you have a 386 and no boards, but a bunch of 486 boards?
Click to expand...

That's exactly it, besides I wanted one that supports L2 cache.
I suppose I could just use the 486 DX33 and overclock it to 40MHz, but then my 386 chip has no home.
 
I've never heard of those, but yes, they would have to, unless it's really a 386 board and it supports 486 "upgrades" like the (unfortunately ruined) Kingston 486/Now I have.

If you're in the market for a 386 board, I have a few, but all of mine already have chips or are soldered Am386-40. I'd just stick your 386 in a case and put it on a shelf until it's needed - if you want a 386 box buy one, because unlike 486 boards 386 boards typically end up sold with the CPU like earlier boards (8086, 8088, V20, V30, 286) were, even secondhand.
 
TheLazy1 said:
What about boards that supported both 386 and 486 chips?
Did they use a separate socket or something?
Click to expand...

Yes. The 386 socket is not the same as a 486 socket, and the difference in pinout would make for a really ugly implementation. So there would be two sockets on one of those boards.

But I wouldn't say "No, it is not possible at all" ... with enough support circuitry, I bet you could build a ridiculous back converter! :) The performance would be relatively terrible and you'd be missing 486 specific instructions and features and overall would be a silly waste of time... but definitely "possible" ;)
 
Aren't the most ridiculous things the ones most worth doing? :)
I'll just stick with my 486dx-33 then, while the board does have L2 it has a stupid Y2K bug :(
 
I think there might be 386/486 combo motherboards (use one or the other) but I have not seen them myself if they do exist.
 
Were there any DOS fixes for a bios's buggy RTC code?
The last time I played with that board I ended up patching the freedos kernel to always return 2010 - but that is just plain sick.
A crime against humanity if you will.
 
TheLazy1 said:
Were there any DOS fixes for a bios's buggy RTC code?...
Click to expand...

You are referring to the internal registers of the RTC, where the "Century Byte" doesn't roll-over when the year goes from '99' to '00'. But the problem you describe sounds more like a drained CMOS battery. Did it happen every time you ran the system?
 
Raven said:
Indeed - even my IBM PC AT 5170 has no problem believing that it's 2010, in fact. :p
Click to expand...

Yeah, every computer I've known since forever handles way into 20xx years; I guess they believed they would last longer... (and they do, in some cases, but not generally.)

TheLazy1 said:
Were there any DOS fixes for a bios's buggy RTC code?
The last time I played with that board I ended up patching the freedos kernel to always return 2010 - but that is just plain sick.
A crime against humanity if you will.
Click to expand...

If you were going to do that, you should take whatever your RTC source is, back it up as far as it can go, and then return the year as an offset (e.g. if it goes back to 1980, then return year + 30), but still an interesting idea..
 
I found what I think is a 386/486 combo board. It's being sold in the 'Box of Motherboards" thread right now here.

attachment.php


For reference, or if someone wants to buy it.

I am curious how VLB works with a 386, or if it works with a 386.
 
Indeed, Weitek slots, and also often a 487SX Slot (when you had a 486sx installed, you could add a 'coprocessor' - in fact that was a full 486, and the original 486sx CPU was switched off..
 
I've got at least two 386/486 combo boards. But, I just took detailed pictures and will be listing them on ebay now, from the looks of it.
 
I'd be interested in a 386 board is there is one that is not longer than an XT board - which seems to be 27,3 cm / just under 11 inch length.
 
You must log in or register to reply here.
Back
Top