On Jan 2, 2022, at 9:18 PM, Warner Losh <[email protected]> wrote: > > I had accounts on a MicroVAX 2 and a VAX 11/750. The microvax was faster for > most compute jobs, but the 750 with 1/4 the memory handled more users mostly > in text editors with the occasional compile or nroff/troff jobs. IIRC, the > 750 had faster disks... > > Warner
I picked up a copy of “VAX I/O Subsystems: Optimizing Performance”, it gives I/O speeds for SDI and DSSI disks, I don’t doubt that the VAX-11/750 had faster disks if it had RA81 or especially RA82 disks. Here we go, from the HP "OpenVMS I/O Users Reference Manual” for 7.3-1. "On VAX systems, the RD53 and RD54 are 5.25-inch, full-height, Winchester-type drives with average access time of 38 ms and a data transfer rate of 0.625 MB per second.” Even the RA80 can beat that, basically any SDI disk on a VAX-11/750 would be noticeably faster. There is a reason why MicroVAX I and II systems with RD53/54 drives were considered to be good for Performance Tuning training. It’s really easy to notice improvements. Zane
