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A simple 386DX-to-486 upgrade with removable 486

S

southbird

Experienced Member
Joined
Sep 11, 2009
Messages
316
This is something I had once and I can't remember who made it ... it fit into a 386DX socket and provided a 486 as a simple plug-in solution. The 486 was also removable ... it came with a 486DX-33 when I found it, dropped in a DX2 and made a PS/2 386 fly at 66MHz. Anyone at least know what I'm talking about ... and anyone willing to part with one for cheap? :)
 
southbird said:
This is something I had once and I can't remember who made it ... it fit into a 386DX socket and provided a 486 as a simple plug-in solution. The 486 was also removable ... it came with a 486DX-33 when I found it, dropped in a DX2 and made a PS/2 386 fly at 66MHz. Anyone at least know what I'm talking about ... and anyone willing to part with one for cheap? :)
Click to expand...

Made by Hypertec: http://www.IBMMuseum.com/OhlandL/CPU/8570_DX33_Upgrade.html
 
If i remember right there was a similar device to put a 386 on a 286 motherboard.

Now, the interesting question is if you upgrade a 286 to a 386, can you remove the 386 from the upgrade card and plug the 486 upgrade into that socket? It might not perform well because of the slower 286 bus and memory, but it could run the full instruction set of a 486. I would like to see that.
 
carangil said:
If i remember right there was a similar device to put a 386 on a 286 motherboard.

Now, the interesting question is if you upgrade a 286 to a 386, can you remove the 386 from the upgrade card and plug the 486 upgrade into that socket? It might not perform well because of the slower 286 bus and memory, but it could run the full instruction set of a 486. I would like to see that.
Click to expand...

Yup. Asus made a 286-to-486 upgrade called The AU486PLC.

And according to this article, a company called Improve Technology had the "Make-it 386" that was a 286->386 upgrade.

http://www.smartcomputing.com/Edito...s/1993/jun93/93n0609.asp&articleid=5898&guid=

I collected a lot of 386/486/Pentium stuff over the years but most of it is gone. I'll have to look through my stuff. I'm pretty sure I had some Cyrix stuff and a couple of Intel Overdrive products as well.
 
carangil said:
If i remember right there was a similar device to put a 386 on a 286 motherboard.

Now, the interesting question is if you upgrade a 286 to a 386, can you remove the 386 from the upgrade card and plug the 486 upgrade into that socket? It might not perform well because of the slower 286 bus and memory, but it could run the full instruction set of a 486. I would like to see that.
Click to expand...

Yeah, 286-to-486 is not quite such an amazing feat. :) But I like the "upgradeable upgrader" that I mentioned in as my opener here since I could experiment with different plug-in chips. I actually had a "MakeIt 486" once that fit a 286 motherboard ... I guess it needed a RAM upgrade though, because all I remember was getting parity errors of death. (When it booted fine without the device.) This was WAY after-market though; just playing with some junk I found.


But for purely specific 386->486 upgrading, I am seeing some of those Cryix chips on eBay, so I may consider that if the one I actually want is unobtainable.
 
I own a couple of 286 to 486 upgrades. The best possible one I have seen uses IBM 486SLC2-66MHz (16kb internal cache). I have one made by Evergreen. These are great if you can get them working. I'm still having a conflict with the one in my AT. It messes up the A20 handler. The fastest upgrade that I have that I have working correctly is the Buffalo TI486SXL-40 modules (8kb internal cache). Mine runs at 48MHz (8MHz with 6x multiplier). The real problem with using upgrade chips is that your system bus is still slow and memory performance stinks bigtime. Performance drops like a rock once you start accessing memory outside of internal cache.

There are many 386-486 upgrade modules available, and you can upgrade to just about any 486 chip under the sun...even 5x86-133. The best one I own uses IBM Blue Lightning 75MHz (clocked at 66MHz). The TI486SXL chips make good upgrades if you can actually get them going on your board. Most pre DLC 386 boards hate them. Cyrix 486DRx2 chips are probably the most hassle free 486 drop in upgrades.
 
AC or anyone: Ever see an upgrade that piggybacks a surface mount 286 like this:

286.jpg


Sorry for the poor photo, but it's the only one I have and I don't feel like opening the case right now. I remember having a Make-It 486, but I think it was for a smaller size SM 286 ... but I could be mixing up my old memories with 386SXs :)
 
I am pretty certain that the make it 486 kit at one point offered an adapter for the 286 CPUs soldered onto the motherboard.

I wonder if it would be possible to fashion your own adapter by soldering together two PLCC 68pin sockets...
 
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