LGP-30 software

Christian, I used to work on an LGP-30 over 37 years ago and was fortunate in having ACT V as the complier for the machine. You will see Graeme Scott's name in the first part of the ACT V compiler tape on your website. After joining IBM in 1969 I happened to encounter Graeme working for Bell Northern Research in Ottawa in 1972 or 1973. He mentioned that he had written ACT V in a rather short time as he was frustrated at how long it took to do things in ACT III. He turned out what I still believe was a masterful piece of software that exploited the LGP-30 hardware capability to its maximum. You will see that the compiled code branches to highly optimized run-time subroutines in the ACT V Run Time portion of the package. The compiled code executed at a very reasonable rate for such a slow machine as every floating point operation ran optimized. The compiler itself used HASH coding to determine if a variable was a reserved word in the language and if not, was stored away in the hash table of variables. Optimal Assembly routines were devised for most drum memory machines like the LGP-30, IBM 650 and Bendix G-15. The ACT V compiler made assembly coding on the LGP-30 unnecessary. It was hard to outperform the compiled ACT V code. Compile times for ACT V were about 1/3 that of ACT III. And with the Load & Go compiler, you didn't need to reload the run-time routines [or the compiler after execution]. The 4096 word machine seemed reasonably sized for many problems. Unfortunately I had lost any and all LGP-30 documentation many years ago but if you put up the ACT V material you have on your web-site, I can probably offer some additional comments as it will likely jog my brain cells that haven't thought about these things for many years. Paul Tardif [former LGP-30 programmer and technician] -- J.Paul Tardif 17 Lyall Avenue Toronto, Ontario CANADA M4E 1V7 (416) 694-5309 FAX: 416 694-2381