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Intel 386 on a IBM 5155 or 5160?

Intel Inbosard 386 accellerator for PC and PX/XT

Intel Inbosard 386 accellerator for PC and PX/XT

ivanthetolerable said:
I saw this card on ebay and it looks interesting. Will it work on a 5155 or 5160? What does software support look like? Will it be pretty much a 386 with 640k ram?

https://www.ebay.ca/itm/Intel-Inboard-386-PC-PC-XT-8088-replacement-in-box/265099076824
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Yes, it is a simple upgrade for a PC or PC/XT. You simply drop it in to a free long slot, pop the original CPU from it's socket, and connect the cable from the card to the socket and install the drivers that come with the card. You can even pull the 386 CPU off of the card and drop in a 486 CPU (a Cyrix CX486DRX2-20/40GP 40MHz clock doubled CPU) that will max out the speed of the system at 33MHz without doing anything special (the 486 is limited by the oscillator on the 386 accelerator card unless you are brave enough with a solder gun to replace it).

If you get really lucky and can find a 2 MB daughter card for the InBoard (or an even rarer 4MB daughter card), you can run Windows 3.0 (special Intel edition for the Inboard you can now easily find online and download). Your total RAM without a daughter card is 1MB, With a 2MB daughter card you have 3MB and 5M with a 4MB daughtercard. I run one of these Inboard 386 cards, dropped in a Cyrix CX486DRX2-20/40GP in less than 5 minutes since it's a 133-pin compatible replacement, installed the drivers, and found a 4MB daughter card - so I'm able to run Windows 3.1 in enhanced mode in all of its glory with dozens of apps (doing so requires some driver file replacements from the special Intel edition and a few config.sys mods - again, fully documented here in the forums). It really helps if you also have an XTIDE to run your HDD as a CF or IDE drive which removes disk access bottlenecks - the system flies.

Here is my present build I built in 2016 with lots of detail - The Big Blue Beast. Since my build others braver than I have taken it even further with faster CPUs and mods that are quite impressive easily breaking the 33MHz barrier but with a bit more effort.


Regards,
Mike
 
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yes its interesting, you can probably find the orchid tiny tubo 286 upgrade board for half the price. Its an oddity and you are NOT going to really be running 386/486 programs on an 8 bit data bus at anywhere near the speeds it claims.
 
An Inboard/386 is something you have because it's an oddity; applying gonzo impractical upgrades to vintage computers is a significant slice of the fun people get out of the hobby. I ocassionally do it myself. ;)

Honestly one of those tiny half-size AT 386SX motherboards with a 33 or 40Mhz CPU and 8MB of RAM would probably run rings around an Inboard/386, to say nothing of an actual 486DX board which are also available in small form-factors that aren't too hard to cram into a 5160. That sort of thing was fun to do back in the late 1990's when all this stuff was just "junk", but people might get offended if you gutted a working one for that kind of upgrade today.

(I wouldn't, but I gutted a *lot* of 5160's back in the day so I'm immune to feeling sorry for them.)
 
As others said, it's the fun of maxing out a system - any system. I also have a slew of other systems - 286, 386, 486, and Pentiums etc. I loved taking my 3.4GHz Pentium Dell 8400 and adding SSDs, max memory, and top video cards that are dirt cheap now and run everything from DOS to 32-bit Win OSes and software than can't run on 64-bit modern systems - fun!

Then again, in 2016 when I built my XT-486 all of the parts were dirt cheap on eBay. Now? I don't think I'd do it seeing the current costs.

Mike
 
Eudimorphodon said:
An Inboard/386 is something you have because it's an oddity; applying gonzo impractical upgrades to vintage computers is a significant slice of the fun people get out of the hobby. I ocassionally do it myself. ;)

Honestly one of those tiny half-size AT 386SX motherboards with a 33 or 40Mhz CPU and 8MB of RAM would probably run rings around an Inboard/386, to say nothing of an actual 486DX board which are also available in small form-factors that aren't too hard to cram into a 5160. That sort of thing was fun to do back in the late 1990's when all this stuff was just "junk", but people might get offended if you gutted a working one for that kind of upgrade today.

(I wouldn't, but I gutted a *lot* of 5160's back in the day so I'm immune to feeling sorry for them.)
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I see the point, I'm just not willing to throw my money away when the prices are that high. A fully configured 386 machine does more than a 386 upgrade in an PC/XT/AT class machine. If the price for the upgrade were more reasonable, it would be less of a problem justifying the purchase.
 
VERAULT said:
i threw away so many harris 20mhz 286 systems and 40mhz 386 systems..... ahh,, who knew?!
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I have a 20mhz Harris 286 system and a loose 25mhz Harris chip. I haven't upgraded it because I don't want to have to upgrade the oscillator, and possibly other parts that might not be rated for the 25mhz speed.
 
animekenji said:
I have a 20mhz Harris 286 system and a loose 25mhz Harris chip. I haven't upgraded it because I don't want to have to upgrade the oscillator, and possibly other parts that might not be rated for the 25mhz speed.
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finding memory that can handle running at 0-wait at 25MHz is almost impossible

0-wait 20MHz is faster than 1-wait 25MHz in all the real world tests and most of the synthetic benchmarks I've tried

PS your 20MHz rated chip will very possibly rune fine at 25, mine did
 
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