Information Technology Reference
In-Depth Information
Because our IBM 1401 computers were used for actual Public Health Service
applications during the day, the time available for testing was usually late at night.
Programming offices and computer rooms in the 1960s were fairly busy places at
midnight and afterward.
Due to the shortage of convenient test times, all programmers in this era be-
came proficient at desk checking . This was an early and manual precursor to static
analysis. We went through our program listings and checked the accuracy of all
algorithms and the branching structure to be sure our code went to the right place
on every branch.
Although interpreted languages such as BASIC would become available in this
decade, the majority of languages used for commercial and government applica-
tions needed to be compiled. This means that testing had to be preceded by com-
pilation, and both activities were normally carried out late at night.
Submitting a faulty program for compilation usually meant at least one wasted
day because computer time for a new compilation would not be available until the
following night. It is obvious why careful desk checking prior to compilation and
testing was the first line of defense against bugs.
In today's world, enormous computer capacity is available to all programmers
24 hours a day, 365 days a year. In the 1960s, the situation was different. Program-
mers needed to queue for available computer time slots and sometimes a program-
mer might only be allowed 15 to 30 minutes a day for compilation and testing.
The card decks were carried about in special trays, and for large programs they
could be quite heavy. Woe betide a programmer who dropped a tray and got the
deck out of sequence or the cards bent. If the cards got bent or warped and swollen
from spilled water or coffee, repunching the deck was sometimes the only option.
The outputs from our programs were printed on an IBM 1403 printer, which,
as I recall, was a chain-driven printer that was quite noisy. The spinning chains
had characters on them, and a hammer would strike it through the paper at just the
right instant. It was fast and printed at a rate of about 600 lines of text per minute.
These printers had surprisingly clear and pleasing type styles and faces. In fact,
the type styles were much better than later dot-matrix printers. It would not be un-
til laser printers and inkjets arrived that the IBM 1403 was surpassed in typograph-
ical elegance.
Search WWH ::




Custom Search