In this section I'll accumulate documentation for the LGP-21 (and LGP-30,
in the case of software, with which the '21 is partly compatible).
- This operating procedure sheet
came with this machine.
- Here are some photographs of the machine, reasonably
unorganized for now.
- The memory and number
representation scheme of the LGP-21 and LGP-30 will seem
rather bizarre if you've only worked with "modern" machines.
punched tape digit representations was in a drawer in one of
the Tally devices.
- Here's a price sheet
originally published in Weik's "A Third Survey of Domestic
Electronic Digital Computing Systems" Report No. 1115, March
- This example of LGP punched tape digit
representations was in a drawer in one of the Tally
- In a Tally drawer was a few immaculate LGP-21 Optimum Address
Calculator, a circular slide rule for determining the
most-optimum memory location. Here's the rear with order chart.
- LGP computers used customized Friden Flexowriters
as "console" and boot device. They use this very peculiar
6-bit character code, in two
cases, with ITA2-like FIGS/LTRS case-control characters; the
character codes map directly (in hardware!) to machine
instruction opcodes. I swiped this chart from Dik Winter's
website, without permission. Note Dik's comment about "l" vs.
"1"... there is a unique way to distinguish internally between
the two, but not visually on paper!
- Ed Thelen's incredibly useful
"http://ed-thelen.org/comp-hist/lgp-30.html" LGP-30 website.
The LGP-21 is almost-code-compatible with the '30. See also his
="http://ed-thelen.org/comp-hist" antique computer