Here is an interesting look back at the first digital computers we used for computation. It is a lovely BBC video about a restored system from bays of old.
Programming was limited as old systems had 90 bytes of memory, not 900, not 9000 not 90,000, not 900,000 or 9 meg, etc. – just 90 bytes !! A real challenge for the programmers of that era.
Pay particular attention to the punched paper tape descriptions. This was the “I/O” of the day. Fortunately for me, my then employer Burroughs Federal Systems Division if McLean, Virginia, (mid-1970′s) had the latest kit from the factory in Paoli, Pennsylvannia. We had a Burroughs B-3500 with a cobol compiler and it could generate machine code for the striped-ledger accounting machines that Burroughs sold to make banks. The L-5000, L-6500 and L-8000 systems were programmed via punched-paper tape. To make it easier to program the L-series, our B-3500 system had a version of cobol known as L-Cobol, presumably for ‘Little’-Cobol and we also had a paper-tape punch machine to output machine code from the L-Cobol compiler.
The work flow was : 1) write cobol statements on coding sheets of paper, 2) use 80 column card punch to turn code from your coding sheets into a deck of several thousand 80 colum cards, 3) go to B-3500 4) place deck into 80 column card reader, 4) go to B-3500 control control – the ‘SPO’ – for system print-out, 5) put in a command to the MCP – the Master Control Program, 6) wait for the L-Cobol compiler to run thus producing a compiler listing on our 132 column printers, and if no errors, the generated machine code was punched out on the paper-tape punch, 7) carefully transport paper-tape to your target L-series system, 8) power-on and reboot that system, 9) invoke load command so L-system would read it’s ‘new’ program from the paper-tape, 10) test, 11) a bug ? Drat !!, do steps 1 thru 11 until success
http://www.bbc.co.uk/news/technology-20155028
While my earliest experiences were with ibm 1401 and ibm 1620 computers, these had moved on to the point where we could use punched cards rather than plug-boards as a programming tool.
Source : jnorthr[dot]wordpress[dot]com
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