[cctalk] Re: mainframe vs mini

On Fri, Mar 10, 2023 at 7:01 PM Jon Elson via cctalk <cctalk(a)classiccmp.org> wrote: And all the OS/360 variants were so late that they introduced three other operating systems as a stopgap to allow IBM to actually ship systems that were usable by customers. First came Basic Operating System/360 (BOS/360), which was pretty much cards in and out (plus printer), Tape Operating System/360 (TOS/360) which was what it sounded like, and then a bit later in June 1966, Disk Operating System/360 (DOS/360). DOS was fully expected to just fade away once OS/360 was completed as it was assumed everyone would quickly upgrade, but in typical customer fashion it Simply Would Not Die and even lives on today a z/VSE. DOS was for some time the most popular operating system in the world. On the original question, yeah sure, there were/are "frames" holding things, but also IBM's word mainframe really just means "Big-ass computers made by IBM" and they like to get testy when someone calls something from another manufacturer a mainframe. So this is the definition assumed by anyone who has drunk enough of the IBM Coolaid (and the related myths about robustness and security). I'm a software person so I'm much more interested in the functionality and applications of a system when comparing them. So for example an HP 3000 "minicomputer" in retrospect was comparable to a mainframe because you did pretty much all the same things you would do on an IBM MVS system and many of them in very similar ways (the MPE OS and even some of the CPU hardware design like the two-bit Condition Code and Channel / Selector Channel setup were very clearly inspired by IBM). If you were a huge bank or Sears, etc. then you bought a mainframe because that was really your only option, but if you were a little bank in Guatemala,a medium sized wholesale distributor, consumer electronics, maternity clothing, or drugstore retail chain, etc. then you bought something like a 3000 and did all the same stuff (COBOL, block mode online terminals, batch, etc.) just way cheaper and more easily. Of course all these things were about the performance of a $1 microcontroller of today, so that seems like an acceptable categorization too :) G.