Saturday, February 25, 2017

It's In the Code

  Many years ago, when the Earth was young and we slew the dinosaurs with our mighty slide rules, there was a thing called  a DECUS Symposium. They were like a week long Grateful Dead concert, except they were aimed at people who were interested in DEC computing rather than at Dead Heads. There were the equivalents of rock stars (developers), excited fans  grooving together over the true word (attendees), and even the equivalent of the parking lot vendor scene (DEXPO, held next door to the Symposium). And there was plenty of intoxication at both types of events. Many thousands of people with like interests from all over the world came to share their enthusiasm for the universe that was all things DEC.

  I was lucky enough to attend several of these get-togethers (DECUS Symposia, not Grateful Dead concerts - well, actually, I was lucky enough to attend several of those as well, but that's another story).

  DECUS Symposia during the day consisted of many presentations, called "Sessions". Presented by DEC, other companies marketing products and services, or dedicated fans of DEC, they covered a myriad of subjects. Some interesting, others not so much. Some all dry technical material, others lighter and with a touch of humor (especially the Q&A sessions where DEC developers were asked about...curious..things the company had done or not done).


  Sessions at night tended to be...looser. The most (in)famous of these were the RSX Magic Sessions. These sessions were attended by the hard core RSX folk, from inside and outside of DEC. If you imagine a cross between "Alice in Wonderland" and "Where the Wild Things Are" you'll have a notion of the atmosphere that prevailed at these. And beer. There was a lot of beer. In the early days, you had to answer a question about how the RSX Exec worked to prove you were worthy of admission, although, sadly, this requirement was omitted in later years.

  In any case, at one of these convocations, DEC RSX expert Brian McCarthy presented an absolutely hysterical presentation he called "It's In the Code". It consisted of examples from the RSX source code of strange and funny things that were in the source code and attending comments. I don't recall many of the details, as I had consumed much beer at the time, but, I was reminded of this a few days ago while reading the RSX clock queue handling code, when I ran across a funny comment. For your amusement...

*************************************************************************************
        MOV     $TKPS,R5    ;;; Get the ticks/second
        MUL     #10.,R5         ;;; multiply * 10
        CMP     (R4),R5         ;;; are we in range?
        BLO     7$                   ;;; if LO, yes, finish the interrupt
;+
;  If we cannot process a clock interrupt within 10 seconds, we are
;       no longer processing in real time, and we may as well become
;       a VAX ... Call an end to this ... NOW!
;-

        BGCK$A  BF.SAN,BE.IDC,<FATAL>   ;;; System massively confused


************************************************************************************

  it was during a period of time when the RSX clan couldn't resist throwing a little shade on the VAX/VMS folks whenever the opportunity presented itself. Ah, good times...we'll not see their like again...