Processor upgrade cards

[Ruud]

I own a ISA card that upgrades an 8088 machine to a 80286 one. I have seen threads that handle other type of upgrade cards. My question: does anybody know of a (open/free) project of such a card?

Maybe an idea for you, Sergey?

 

[JvV]

Don't know of any project of such, but i own such a card myself! (Not an Orchid Tiny Turbo card). Great idea for an project for XT to 286 or better 386, i know the databus will be the bottleneck but still.

 

[MicroCoreLabs]

The MCL86+ is a drop-in replacement for the 8088 and when accelerated runs even faster than an 80286.

 

[MicroCoreLabs]

It could also be used to implement an intensive motherboard tester which can run tests written in C and access peripherals over the 8088 local bus interface. User would interact with the Teensy microcontroller over the USB UART. Since all code runs from the Teensy even the motherboard interface logic to the EPROM could be debugged.

 

[Ruud]

The MCL86+ is a drop-in replacement for the 8088 and when accelerated runs even faster than an 80286.

I know about your project and I only can say I admire it a lot. I'm still thinking about getting one but I have too may projects of my own: I simply lack the time to give it the needed attention.

The background of this question is curiosity: I want to find out how the hardware is realized. I'm not interested in the extra speed: if I need speed I will just use a faster machine.

Just for FYI: if I buy a MCL86+, being a 6502 fan as well, one thing I would try is to run a 65816 like CPU on a 8088 motherboard. Just for fun. I think I will put it on my Christmas wishing list

 

[MicroCoreLabs]

I know about your project and I only can say I admire it a lot.

Thank you.

if I buy a MCL86+, being a 6502 fan as well, one thing I would try is to run a 65816 like CPU on a 8088 motherboard.

We both had the same idea. I was thinking of porting my MCL65+ (6502 emulation) , MCLZ8 (Z80 emulation), or MCL68 (68000 emulation) code to the MCL86+ as a project to demonstrate what the IBM Personal Computer would have been like if one of these microprocessors was chosen instead of the 8088. Porting the CPU code would be easy, but the question would then be what software or BIOS could run on it? Running the TRS-80 Model I or Apple II BIOS ROMs would be relatively easy. I did this already on a NABU...

 

[chris_nh]

I like your idea Ruud! I've been thinking on an accelerator design based on a V30 cpu. My understanding of the hardware interface is we would need to produce an extra bus cycle on 16 bit transfers because we can only get 8 bits at a time. Maybe this could be accomplished with a counter and a ROM to produce the signals for those transfers when needed. The accelerator would have on-board 16-bit RAM and could probably ignore the 8-bit ram on the motherboard after boot, which I believe is similar to the inboard 386, and could cache the BIOS ROMs into the 16-bit RAM. Still gotta figure out how to handle DMA transfers. Inspiration for the design would be the Quadram Quadsprint which is based on an 8086.

 

[Timo W.]

I would love to see a modern 286 PLCC to 386SX upgrade adapter. Looking for one for my Schneider Tower AT for years now.