Re: HP Series 9000 early 1980’s computer hardware

The 9000 Series 500 is very different from later 9000s. I don?t think there more than one speed of CPU, although there was an early and later CPU with the later CPU having a floating-point unit onboard. What you get out of a 9000 Series 550 over a Series 520 (aka 9020) is mostly more I/O slots, as I recall the 9020 had a short I/O cage. But I think the processor cage is the same size and can host about the same sets of cards. The CPU is a 32-bit stack machine, very like a wide classic-3000, and there can be up to three CPUs in a system. There is an IOP that front-ends a CIO-type I/O bus (same bus and some of the same peripheral cards used in early PA-RISC systems) and I think you can have two IOPs in a system. HP-UX for them is very interesting from a historical perspective in that the Unix kernel is a complete rewrite. It is hosted on top of HP?s ?SUN OS? operating system (there is also a single-user BASIC system for the 9020, also hosted on SUN OS) and written in HP?s MODCAL language. The filesystem is HP?s Structured Directory Format. The userland is largely made up of ports from AT&T System III (and later System V) and 4BSD. So when it is running HP-UX it looks like Unix, with some exceptions. One is that if you open and read a directory from your C program there are no entries for . (current) or .. (parent) directories; these are done in SDF?s directory entry and not present in the actual Unix directory. Yes, ls -a shows them: it is faking them to make it look more like Unix! -Frank McConnell (supported Wollongong?s TCP/IP on these) On May 17, 2018, at 13:48, Ed Sharpe wrote: