Odd "endianness" [was Re: RE: Base 64 posts to the list]

jim stephens jwsmail at jwsss.com
Thu Dec 8 01:03:20 CST 2016

On 12/7/2016 10:42 PM, Chuck Guzis wrote:
> On 12/07/2016 12:46 PM, Rich Alderson wrote:
>> Neither of those is entirely accurate.  9-track tapes on the PDP-10
>> used one of the following encodings:
> The last time that I had to deal with PDP-10 tapes, admittedly also 40
> years ago was essentially core-dump format.  5 7-bit characters per
> word, with one bit unused; words packed end-to-end; i.e. 9 frames for 2
> PDP 10 words.
> It was the "Adventure" game, smuggled to me by a DEC field engineer.
> Translating to CDC display code and then dealing with the differences in
> FORTRAN made the work interesting.   The thing spread like wildfire
> throughout the CDC corporate system and was ardently hunted and purged
> by COMSOURCE administrators.
> --Chuck
The Multics version I saw came from a Fortran version taken from a 
PDP10.  If I'm not mistaken it was directly from the timeshare system 
they used in Billerica,Ma where Don Woods worked.  After some massaging 
it was unleashed on Multics.  Most of Honeywell was wiped out by copies 
on various machines for quite some time (2 or 3 months?) before people 
quit risking getting into trouble to play it anyway.

There were two files, the main fortran file, and the table file with the 
cave encoding.  I suspect anyone who got a copy of the latter, and read 
the former wrote a program to print out a very useful cheat sheet.  If 
you had that, you could solve all of the puzzles from data in the table, 
and you only had to worry about the problems associated with random 

The PDP-10 source did have a schedule feature to allow the game to only 
be played during certain hours, but in the copy we were running that was 
bypassed to allow it to run 24 / 7.


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