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Great Hierophant
April 24th, 2012, 12:28 PM
What are the fastest system or motherboard out there for the 8088/8086 that was PC compatible (even a semi compatible like the Jr. or the Tandy 2000 with its 80186) would do? There are several types of fast

Fastest factory-pure MHz,

Fastest stable user overclock

No 286s or better, machine must use use a 8088/80188/V20/8086/V30/80186

Fastest with accelerator board, not a system board replacement (286s or better allowed here)

pearce_jj
April 24th, 2012, 01:02 PM
I'd guess something with a 16MHz V30. Although later 186 CPUs (the XL's (http://vintage-blog.peacon.co.uk/wiki/Intel_80186)) ran at up to 25MHz and the co-pro was essentially a 387 too.

sergey
April 25th, 2012, 02:24 PM
What are the fastest system or motherboard out there for the 8088/8086 that was PC compatible (even a semi compatible like the Jr. or the Tandy 2000 with its 80186) would do? There are several types of fast

Fastest factory-pure MHz,

Fastest stable user overclock

No 286s or better, machine must use use a 8088/80188/V20/8086/V30/80186

Fastest with accelerator board, not a system board replacement (286s or better allowed here)

My very own board (http://www.malinov.com/Home/sergeys-projects/sergey-s-xt) goes up to 13.33 MHz using 16 MHz NEC V20HL CPU. I guess it will go higher, up to 16 MHz, I just couldn't find a 48 MHz oscillator for testing...
It also uses SRAM, so no CPU time wasted for DRAM refresh :-)

N8VEM project's ECB SBC-188 board (http://n8vem-sbc.pbworks.com/w/page/28238657/ECB%20SBC-188) runs on 25 MHz using 80C188 CPU. Although this board is not very PC compatible (there is some BIOS-level compatibility, and it can boot MS-DOS).

eeguru
April 25th, 2012, 05:05 PM
There are a few through-hole TLL PLLs still available. You could make 48 MHz from a lower crystal or discrete XO.

Chuck(G)
April 25th, 2012, 07:49 PM
If we're talking about something that doesn't have a protected mode and executes x86 code, I'd suppose that the NEC µPD70136A(V33A) or µPD70236A (V53A) would probably take the cake. Legitimate speeds to 20MHz and a very heavily optimized internal core (cycle for cycle, about 4x a V30). 24 bit addressing (has mapping registers internally). Add a µPD72291 numeric coprocessor and it would be hard to beat.

Of course, if you went to 8086 emulation by a different processor, that would change things considerably.

Edit: After a bit of thought, I remembered some of the "PC on a chip" systems. In pure 8086-type non-protected, the winner might be the Vadem/Amphus VG330 with a V30MX core running at 32MHz. Here's the data manual (http://www.amphus.com/chips/pdf/330dm.pdf) (Warning: 388 pages)