hammond@petrus.UUCP (04/23/85)
While doing benchmarks on floating point performance, I noticed that our 11/785 with FPA took several times as long as an 11/750 w/FPA to do double multiplies. Our DEC salesman claims that the 11/785 FPA has a microcode bug in the multiply and that the machine is wired to ignore the FPA for multiply. I think he claimed that there should be an ECO out for this (new microcode). If you have an 11/785 with FPA, check by multiplying two non zero numbers (try 1234567.8 * 10) a million times. If you have the bug it willl take about 20 seconds (i.e. 20 micro seconds per loop), with a fixed FPA it should take 5 to 10 seconds (our 11/750 takes 7.7). Rich Hammond {allegra | decvax | ucbvax}!bellcore!hammond