[TUHS] BASIC, RSTS, and UNIX

[Ron Natalie]

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.

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