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Drop-in 8088 CPU Emulator for the IBM PC - MCL86+

MicroCoreLabs

Experienced Member
Joined
Feb 12, 2016
Messages
131
Quick update on the MCL86+:

I add some code to mirror the ROM and RAM of my IBM 5155 using the Teensy's internal memory and ran a few performance programs from a DOS 3.2 Virtual Disk.

First I tried running cycle accurate which counts 8088 clocks and uses the motherboard's RAM and ROM which worked fine as before.

But when this new acceleration was enabled which uses just the mirrored memory (and none of the motherboard RAM) the speed increase is dramatic.

Looks like the performance of this machine is in the around that of a x386. :)

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bladamson

Veteran Member
Joined
Nov 11, 2018
Messages
914
Location
Appalachia
Oh now this is a cool project. I am not sure how I missed it before! :O And I see that there's even more cool stuff on your github!

I know it's a heck of a lot more complicated, but any chance of an eventual 386 core and >640k of mirrored memory? It would be rad to be able to run 386 protected mode development tools on my H-150. :D

Regardless, if you make another run sometime or still have some extras, I'd happily throw you a few bucks for a couple of bare boards!
 

MicroCoreLabs

Experienced Member
Joined
Feb 12, 2016
Messages
131
I know it's a heck of a lot more complicated, but any chance of an eventual 386 core and >640k of mirrored memory?
Good question - its just software so probably no reason why it cant emulate a x386 :) Teensy 4.1 only has 1MB of RAM so couldn't emulate all motherboard memory, but a cache would definitely be possible...

I thought it might also be fun to implement a project similar to my MCL65-Fast which simply runs C code on the 800Mhz Teensy and has access to the motherboard peripherals: MCL65-Fast

Another project could be to port the MCL65+, MCLZ8, or MCL68 and see what it would have been like if they had decided to run the IBM PC on a 6502, Z80, or 68000.

Yes. have a few boards if you would like one.
 

1ST1

Veteran Member
Joined
Oct 21, 2014
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1,305
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near frankfurt/m, germany
Hi, how hard is it to change it to work as 8086? For IBM PS/2 Model 30 and Compaq Deskpro.

... and Olivetti M24, M21, M240 (it must run stable at 8 and 10 Mhz bus clock!)

An enhancemet to the NEC V20 / V30 instruction set also would be nice...

Maybe also integrate 8087 emulation?
 

MicroCoreLabs

Experienced Member
Joined
Feb 12, 2016
Messages
131
It wouldn't be hard to add V20 instructions and maybe even 8087 emulation. It is just C code after all. :)

Faster bus speeds might be more challenging though as the local bus is being emulated.
 

MicroCoreLabs

Experienced Member
Joined
Feb 12, 2016
Messages
131
Thanks! Yes I do have some boards available, however it might be less expensive to build a batch of five from the PCB vendor. It cost me less than $25 USD for five of them including shipping, so I think it would cost more for me to ship it international.
 

chjmartin2

Experienced Member
Joined
Dec 26, 2012
Messages
316
Hi,

I am surprised given the lack of available accelerator options that we do not have more interest in this project. I, for one, would love to see this implement the 286 (or 386/486) instruction set, along with DMA transfer detection/cache so as to make a daily driver that is either a) super fast 8088, b) 80286 "socket" upgrade or c) something else entirely. The main reason I think that Ted hasn't pursued further is because there is very little interest it seems. So I am curious how many of you would purchase an MCL86+ if it could be used as a daily 8088 driver albeit at the equivalent of a 10 Mhz AT machine? I know that I for one would spend some $$$ on it.

Thanks,

Chris
 
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