Speaking of the history of IBM 360 architecture... My first job out of college in 1978 was working for Wisconsin Department of Revenue as a LTE (Limited Term Employment) computer programmer. My job was to maintain programs that ran on an IBM Model 360-20. Our 360-20 sported 32k of doughnut memory, a 30 megabyte hard drive, and a couple of tape drives. I had an edit check program I had to maintain. The program checked various fields copied off of Wisconsin tax forms that had been keyed onto a tape using the Centrix system. The edit program I was responsible for maintaining was written in BAS (which later became called BAL, for Basic Assemb-Ler language... or some similar acronym like that.) Every time a user made a request to change how a certain field should be edit-checked I had to figure out whether there were enough bytes in the 360-20's core that could accommodate the request. Sometimes there wasn't.
Every time a new BAS program was created (reassembled) the object code, or object deck, was punched out onto IBM cards. It took 30 minutes to punch out a new object deck. An old computer programmer geezer (who has since been upgraded to the next revision of reality) taught me a trick that I have never forgotten. If by perchance you made a mistake in naming one of the assembler label address fields causing the assembler program to error out because it could not resolve the address location, your only recourse (I though at the time) was to correct the mislabeled label by re-keying in the correct label name and replacing the erroneous card, resubmitting the card deck of source code so that the entire program could be reassembled. Typically, the entire process took another 30 minutes. This old geezer took the "bad" object deck over to a key punch machine, flipped to the specific punched card where the bad machine code with the missing address field was represented in holes, and manually keyed in the correct address using the correct combination of keypunch keys. I estimated the manual-correction process took a human (particularly, a human who knew what he was doing) 5 minutes to fix the error versus another 30 minutes for the computer punch out an entire new object deck. All you then had to do was make a brief note in the hardcopy source code listing indicating the fact that the correct address label had been "manually corrected." Those were the days... and boy, oh boy, I'm so glad of that! Regards, Steven Vincent Johnson www.OrionWorks.com www.zazzle.com/orionworks
