Need Docs for XT RAM Board...

On Nov 10, 2006, at 12:46 PM, Jim Leonard wrote: Oh my. I'm sorry for jumping in, but I got VERY excited about V20 chips back in the day. They truly seemed like something for nothing! The V20 is a drop-in replacement for the 8088, basically a re-implemented 8088 that consumes less power and is a bit faster at the same clock rate. I don't recall exactly how much faster, but I seem to recall maybe 25%. It was certainly enough to be noticeable. On a 4.77MHz system, Norton's SI (system information) would give you a relative rating of (if I recall correctly) 1.7, where the 4.77MHz 8088 was 1.0. It wasn't really a 70% increase; that was due to the imperfections of the Norton benchmark. The V20 also has a 8080 emulation mode, and if you had the appropriate boot disk, you could run CP/M-80 on a V20-equipped PC. You had to execute a special instruction (again I don't recall the details...these are twenty-year-dormant neurons) to kick it into 8080 mode, and this was done by the CP/M bootstrap. It was a neat scheme! The V30 is basically the same thing, but is a drop-in replacement for the 8086. Though the technical details escaped me, I remember very well the feeling of excitement when I got that first V20, plugged it into my no-name 4.77MHz PC/XT clone, and noticed how much faster Turbo Pascal compiled my stuff. :-) -Dave -- Dave McGuire Cape Coral, FL