On 2018-10-26 09:10, Gordon Henderson via cctalk wrote: > I worked for a company that made supercomputer boards out of the i860 at > one point - at the time (very early 90's) they were blindingly fast, > 40Mhz, 3 instructions per clock cycle which, since one was a floating > point multiply and add meant that it was pretty good - at the time. > > However it was a royal PITA to code for although a 32-bit CPU, it would > read memory 64 bits at a time (actually 128 IIRC to satisfy the cache), > with half that 64-bit word being an instruction for the integer unit and > half for the floating point unit, so you effectively had to build a > floating point pipeline by hand coded instructions, so 8 (I think) > instructions to load the pipeline, then each subsequent instruction > would feed another value into the pipe, then another 8 at the end to > empty it. Great for big matrix operations, rubbish for a single add of 2 > FP numbers. > > The issue came when you wanted to take an interrupt - the overhead of > flushing the pipe, reloading it all for the next context, and so on > really bogged it down. > > Not to mention writing assembly code in 2 columns... > > There were quite a few systems built with about 30 boards in them, each > having 2 x i860's and a good few MB of RAM (64MB I think) built.
There was actually a nice PC Mainboard from Hauppauge, with an i486 & i860 on the same board ... Always wanted to have one of those, never found a used one. And it was running some king of Unix back then ... http://www.geekdot.com/hauppauge-4860/ Cheers
