[TUHS] BASIC, RSTS, and UNIX

My BASIC experience came from the HP/2000 (and the HP/3000) systems the Prince George's County (MD) schools had at the time. When I moved on to Johns Hopkins, I was sent a letter in advance of my freshman year from professor Bill Huggins who taught one of the freshman EE classes. The class was to use Basic Plus on a PDP-11/45s using the UNIX operating system. Now at this point, I had a friend whose mother worked in the local DEC (Lanham, MD) office and would let us raid the stock room for things like processor handbooks and the like. I was able to find out about Basic Plus and PDP-11/45 but I was unable to find anything about this UNIX thing. Of course, once I got there I found that the EE computer center was largely run by students under the name of the Undergraduate Computer Society. Mike Muuss was in charge and they had made a deal that if they could get BasicPlus migrated over from RSTS, they could run UNIX on the machine. It turned out not to be that difficult. RSTS, like most DEC OSes, for some reason used EMT for the system calls (contrary to what the processor handbook would recommend). UNIX used TRAP. This means all they had to do is emulate a few RSTS calls. In addition, the only change I believe was to add a system call that disabled the UNIX idea of stack management (Basic Plus like many DEC programs of the day used a relatively small stack in low memory because the actual register saves, etc... were stored elsewhere, it was just function call linkage). The system call was obviously called "nostack." This hadn't been Mike's only foray into Basic. He had his own IBM 1130 and had written a Basic interpretter under contract for the Baltimore County Public Schools. I remember sitting in the "KSR room" at Hopkins and watching him preparing the invoice for payment. Please remit $3000, no stamps please. That last part caused a bit of consternation at the school district. Amusingly, I have my little Raspberry Pi scale model 11/70 front panel churning away on my desk. I can switch it from booting up various UNIXes (mostly I run 2.9 BSD hacked to somewhat look like JHU UNIX) and RSTS which reinforces why we used to refer to it as the Really Sh-tty Timesharing System.