Old CPU question... for lack of a better place... (Page 1/1) 82-T/A [At Work] SEP 29, 11:16 AM I have an 8088 with an NEC V20 processor that runs (switched) between 4.77mhz and 8.77mhz. Technically, the NEC V20 is a workhorse processor that actually runs at 10mhz, but is crystal-defined (I guess, not an EE) to operate at either of those two speeds for x86 compatibility. Can anyone tell me that... if I want to get an 8087 math co-processor for this bad-boy, which processor I should get? Intel 8087-2: https://www.aliexpress.us/i...256804850231748.html I don't know what the "-2" means, but I remember that back in the day, anything following a dash usually referred to the mhz/speed of the processor. I am told that China has a bunch of NOS of these old Intel processors that were being made in Malaysia, Singapore, etc... (or these are reproductions). Anyone an old-school CE or EE here... Randye, TDA, Willie? The world will not end if I can't figure this out, but I want to run some tests on some old software that I have, and these are cheap... so why not? Thanks! RWDPLZ SEP 29, 12:48 PM -2 means it's an 8Mhz processor 8087-5 (5 MHz), 8087-2 (8 MHz) and 8087-1 (10 MHz). 8087-2 would be the same 8Mhz as the NEC V20. If you can, get a ceramic package chip, they should run marginally cooler than the plastic ones. https://dosdays.co.uk/topics/math_coprocessors.php If it doesn't work, try replacing the V20 with an Intel or AMD 8088, the chips are supposed to be compatible. 82-T/A [At Work] SEP 29, 02:13 PM quote Originally posted by RWDPLZ: -2 means it's an 8Mhz processor 8087-5 (5 MHz), 8087-2 (8 MHz) and 8087-1 (10 MHz). 8087-2 would be the same 8Mhz as the NEC V20. If you can, get a ceramic package chip, they should run marginally cooler than the plastic ones. https://dosdays.co.uk/topics/math_coprocessors.php If it doesn't work, try replacing the V20 with an Intel or AMD 8088, the chips are supposed to be compatible. Nice! Thanks Man! That's so interesting... I wonder why they would make the -2 refer to 8Mhz, and not simply just say -8, or the 10Mhz be -10. Lol... Thank you for this! ls3mach SEP 29, 04:26 PM quote Originally posted by 82-T/A [At Work]: Nice! Thanks Man! That's so interesting... I wonder why they would make the -2 refer to 8Mhz, and not simply just say -8, or the 10Mhz be -10. Lol... Thank you for this! I wonder if the -2 has something to do with the BASE system. In tube fittings we use BASE 16. Half inch fittings we call an "8". Swagelok 810-1-8 would be a half by half male connector. We'd call a 5/8 a 10. Cliff Pennock SEP 29, 06:33 PM I don't remember the 8088 running at such high speeds - I vaguely recall them running much slower. I remember having a 80186 which ran at ~8Mhz and had a turbo button making it run at ~10Mhz. So a 8088 running at 8Mhz really surprises me.