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Computer Curiosity

Page history last edited by Alan Hartley-Smith 12 years, 11 months ago

Charivaria

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Introduction

The following has emerged from some old papers.

 

In the early days of computers, they were physically big with several large cabinets of printed circuits, cooling and power supplies. One thing however was small, and that was computer memory. Physically it too was large but its capacity was minuscule in comparison with those of today. Typical storage capacities on delivered systems were 4K, 8K or 16K words, where a computer word was appropriate to the computer's intended design usage and 12, 18 and 24 bits were common and standardisation was rare. [Editors note - the large physical volume of those early computers has been reduced by a huge factor in those of 2011. It is perhaps interesting that the memory capacity of those machines has possibly increased by that same factor in those used by today's much faster, more powerful and widespread examples where gigabytes are the order of the day.]

 

As a result of this deprivation of memory, programmers were selected on their ability to code efficiently using the absolute minimum number of instructions. This ability was prized over the readability of their coding. With hindsight, the extended cost of testing and debugging on the customer's site might have been better used on more storage. It was a painful learning curve and such problems were not envisaged or allowed for.

 

Special instructions that allowed the stored data values to modify the instruction were provided. They were very powerful when used properly but a nightmare when unexpected values occurred or a program jumped out of scope losing control - and very difficult to trace back to the source of the fault. [Editors note - others of you might provide examples of problems encountered and their solutions and possibly the costs incurred against the cost of memory at that time.]

 

Special QUIS tests were created and two examples are given below, with some possible solutions on the last page. What the term stood for is not known nor the reason for its spelling using 'S' rather than 'Z'.

 

EEV QUIS 1        EEV QUIS 2

 

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