3 Operating Systems
ORIGINS OF "OPERATING SYSTEMS"
Back in the early 1950s there were very few computers. Large universities might
have one, as might government research laboratories, and a few big companies. A
scientist of engineer wanting to run a program would book time on the machine.
When their turn came, they would be totally in control of "THE COMPUTER".
They had to load the assembler (or high level language translator), use it to
convert their program to binary instruction format, load the binary version of their
program, start their program using the switches on the front of the computer, feed
data cards to their program as it ran, etc. It all involved a lot of running around
fiddling with card readers (and, later on, magnetic tapes), pressing buttons, flicking
switches. Most people didn't do the job very well and wasted a lot of the time that
they had booked on the machine.
Organizations that had computers soon started to employ professional
"computer operators". Computer operators were responsible for getting maximum
use out of the computing equipment. They would run the language translators and
assemblers for users, they would load binary card decks and get the programs run.
Since they worked full time with the computers, they were familiar with the all the
operating procedures involved and so made many fewer mistakes and wasted much
Since users no longer directly controlled the running of their programs, they had
to write "job control instructions" for the operators. These job control instructions
would tell the operators of any special requirements such as the need to mount a
particular magnetic tape on which a program was to store some generated data.
Computers were changing rapidly in the early '50s. Peripheral devices were
becoming more complex and versatile. Many could operate semi-autonomously.
They could accept a direction from the CPU telling them to transfer some data and
could organize the data transfers so that these occurred while the CPU continued
executing a progr