Tuesday, August 30, 2011

Fun with Emulation #3 - Running a PDP-11/34 with RSTS/E under Ubuntu Linux

The first "real" computer system upon which I ever laid my hot little hands was a PDP-11/34 at Western Kentucky University.  I was attending WKU during the summer between my 11th and 12th-grade years of high school, and one of my typical "go see what's out there" walkabouts led me to the "computer center."  Now, there were several signs posted which suggested that ONLY those students taking SPECIFIC Computer Science classes could gain access to "the PDP", but I explored the terminal room anyway.  One of the admins came out and started throwing a tantrum about the mess left by all the students.  Inspiration hit - I quickly offered to stop by every afternoon and clean up the terminal room, if I could only get access to the PDP...and the deal was done.  I had no idea that TI Silent 700 terminals generated SO much waste paper.

Nonetheless, I was in.  I started playing around with RSTS/E, which was one of DEC's major operating systems in the educational arena, and BASIC-PLUS-2 was THE language of choice.  (Hey, this was 1980.)  One fine day, I was browsing the system tables and noted that there seemed to be 32 terminals connected to the system, although I counted only 24 in the computing center; when I asked, the admins just said, "Well, he gets a key to the closets."  As it turned out, these guys had commandeered closets (scattered throughout the science complex) and wired in either Silent 700 or--*GASP*--LA-36 DECWriter hardcopy terminals.  SCORE!  Printouts on which you could actually TAKE NOTES!  I spent a great deal of time in those closets, and I found that, yes, one COULD write device drivers in BASIC, given enough system calls.  One could also wreak havoc upon peripherals with PIP if you didn't know what you were doing.  I did both.

Bringing back RSTS/E turned out to be the easiest of my emulation projects to date.  After compiling the pdp11 simluator from the SIMH package (linked below), I found the RSTS V9 Archive, which provides a prebuilt, full image of RSTS/E V9.6 on an RP04 disk image; the latter site even provides configuration files for SIMH.  This was literally a ten-minute project, and I had RSTS/E up and running under Ubuntu Linux.  (RSTS/E is text-based only, so I won't bore you with a screenshot.)  If you're longing to write code like:

100 OPEN User_keyboard$ AS FILE #1

Tmp$ = SYS(CHR$(118)+CHR$(18))

LINPUT 'Enter the first line of text';User_input$

...then hie thee to the links below.

The Computer History Simulation Project

RSTS/E V9 Archive


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