LEO III
| Computer | LEO III (13) | |
| Manufactured by | Leo Computers Ltd English Electric Leo Marconi Computers Ltd |
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| Owned by | British Oxygen, Worsley, Manchester | |
| Dates Worked | 1962-65 | |
| I was originally employed by Cerebos Salt in Willesden, London.
I was loaned to the British Oxygen team as the Cerebos machine was
not ready. A desire to move north combined with youthful arrogance
resulted in my resigning from Cerebos and joining BOC. I started at
Worsley in August 1963 (having just got married). I was employed as Junior Programmer at £700 pa eventually dropping the 'Junior'. The initial application was Sales Analysis, invoice data was punched into paper tape by an army of girls and then verified by retyping the same data (discrepancies stopped the machine, the data was visually checked and, if needed, corrections made). |
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| Programming | We used an assembler code with numeric addressing (Section and
sub-section (? forgotten details). Operation codes were numeric
00-load word 01-add word etc. (Virtually) all processing took place
in in a single (double word) register . The program was punched onto P/T (paper tape) compiled and stored on M/T (magnetic tape). As far as I remember any standard routines were added (as P/T prior to compilation. All I/O (including tape buffering) had to be included in the program. Compilation took place overnight and any syntax errors were not forgiven. Code was checked and double checked by another programmer prior to submission. If a test failed you got a 'core dump' (in hexadecimal) with any output. That was when the work got really interesting. |
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| Hardware | The LEO III comprised 30 odd 6 foot cabinets containing circuit boards,(Ampex?), Magnetic tape units (8) etc. (Analex ?) Line printers (1200lpm). Paper tape readers and a large console with lights. (not as many as the EE KDF8(?) console which starred in many films and TV programs where a 'computer' was required. It had rows of illuminated switches that the operator could play like an organ). | |
| Software | The LEO III had one of the earliest multi-programming operating systems, up to 3 jobs could run simultaneously. Printing was usually spooled so that one of those jobs kept the printer busy. | |
 A LEO III at J Lyons |
 Colonial Mutual Life Melbourne |
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| Photos from LEO Computer Society Web Site | ||
| Links |
LEO Computers Society - dedicated to keeping the memory fresh NAHC/LEO Web Site - repository of Documents Frank Skinner - an other memoir |
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