LGP-21 software

The LGP-21 is a transistorized version of the LGP-30, first made in the early 1950's. The LGP-21 is somewhat -- but not completely -- software compatible with the LGP-30. The LGP-21 is somewhat of a superset of the LGP-30, with some serious incompatibilities in I/O. Here is a discussion of LGP-21 and LGP-30 binary software compatibility.

Unfortunately I have no LGP-21 software, except the subroutines and bootstrap given in the LGP-21 Programmers Manual. I continue to search for some, I assume that at least some of the LGP-30's program library was translated for the LGP-21.

The files here were provided by Bob Lilley, to whom we're all indebted for the foresight in preserving them then and for the effort of scanning them now.

(If the files below "don't look like software to me!", please read the Subroutine Manual page.)

Subroutine Manual The Subroutine Manual provided with the LGP-30 contains all of the basic code needed to operate the machine, from bootstraps and program loaders to fancy I/O code.
CrapGame.tiff Bob writes: "Attached is a scan of an LGP-30 program from the 60s which (it says here) allows you to play Craps with the computer. As I remember it, the thing prints out the dice dots on the screen, and you throw again and again until you win or lose.

I see a Transfer Control reference (800g0245 - same as 800t0245 since the 4-bit codes for "g" and "t" are the same) maybe to control when the dice roll.

Hope it works on your machine. It looks as though I was doing a little work on it, from the handwriting...

Actually, it looks like this may be an "object code" printout for a higher-language program - Maybe ACT III? That would explain the weird opcodes. (Remember, the low-order four bits mapped to two or three keyboard characters.) I may have been trying to disassemble it to make some changes..."

LGP30-Blackjack1.jpg Looks like a print out of a BLACKJACK game run.
LGP30-Blackjack2.jpg Looks like a print out of a BLACKJACK game run.
LGP30Program.doc An example from Keith Smillie's LGP-30 simulator.