Long Paper Tape (renamed)
roger.holmes at microspot.co.uk
Fri Mar 23 15:18:39 CDT 2007
> From: woodelf <bfranchuk at jetnet.ab.ca>
>> Later on we moved the compiler onto a GEC 4080 to cross compile
>> for the
>> 920. The 920 program grew and I had to modify the compiler so it
>> produce the binary output in chunks as it exceeded a 1000 foot
>> roll of
>> tape, and anyway I was the only person in the office capable of
>> up a full 1000 foot roll without damaging it.
> I am guessing you get 8 characters per inch of tape.
> That is a 93.75 K of data per tape.
Ten characters per inch, so 120KB. Useful content though was one 18
bit word per three characters, so 40K words. The 920ATC had 128K
words of program/data storage plus another 128K for data only. So if
every instruction was used, that's 3 full reels of tape and possibly
more if there were any pre-loaded tables in the data only section.
The reason it was difficult to wind up was our paper tape winders
only had a 6 of 7 inch back plate, so beyond that I had to use two
fingers to guide both sides of the tape, and got hard skin on both
fingers. It became such a problem the company bought Penny & Giles
1/4 inch cassette tape machines. They worked fine for a while then
the baud rate started drifting as it was derived from an RC network!
Eventually our engineers modified them to use a proper oscillator
In the mean time I had hooked up a direct serial link between the
4080 and the 920ATC running at 9600 baud. My first comms program
(well, sort of).
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