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A look into the past

At the university of Nijmegen I was an inveterate collector of all-things-strange. The old sciences building was cnducive to that behavior, since it had lots and lots of storerooms with 40 years of accumulated junk, most of which were poorly secured or just left unlocked. So wandering through the basements looking for neat stuff was a good student-lunchtime activity. The building was knocked down a few years back, replaced by a shiny green glass-and-steel contraption that is much nicer to work in, but which has a great deal less charm. I still vaguely regret not nicking the elevator maintainence notebook the week before the old building was chained shut. One thing I did pick up was a notebook labeled “ARGS-Logbook” from the computer graphics department. Kept in meticulous handwriting from july 1981 to july 1985, it is full of notes that are both typically WTF and reminiscent of the problems anyone might have when dealing with machine-language programming.

July 1981 It seems impossible to pass parameters as subroutine arguments. Some “arbitrary” value is taken when referencing to such and argument. Strange is however that RET with a non-zero offset does work. (Solved middle of dec ’81). July 1981 The instructions to turn the scanner on/off works the wother way round, i.e. X is 0 for on and 1 for off!! (Doc adapted). September 1981 The conditional branche does not work properly. CMP followed by BRALT results in a branch if greater than! So the neg/pos bit seems to be set wrong (OK after middle of dec ’81). December 1981 Z Status Register instruction can only be used in a specific way. (after partitioning pictures across planes a new partitioning has to be preceded by an INI instruction = reset).

It seems that this was a machine with hardware for image manipulation (with instructions like ARF, area fill), which got a hardware upgrade at the end of 1981. I’ve left out all the complaints about the monitor which also mostlye went away at the end of that year. New issues show up, though:

August 1982 TST instruction does not work correctly (ok now, november 1982, error in cross-assembler). November 1983 Area fill problem. When pixel value at xset, yset = boundary value, the ARFO instruction hangs. February 1985 Recording screen on video impossible because of 60Hz frequency sync. (For changing video frequency, set switches E11, F11 and G11 in graphics store slot 4, need 33 msec refresh at 50Hz, set to 0011 0011)

The last entry in the logbook is the nicest: 18 July 1985 Key of monitor missing. Solution? (Lock turned 90 degrees so key is not needed).

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One Response to “A look into the past”

  1. A look into the past (2) « Bobulate Says:

    [...] wrote recently about a little machine logbook I found in a disused storage cabinet in the old science building. The machine it refers to might be [...]