The First Computer Used
In 1975, I took the subject "Computer Science"
whilst at Hellyer College in Burnie. It's amazing that
Tasmania, the state those of us on mainland Australia often
like to ridicule as being backward, was actually a world
leader in the introduction of computers into the education
Back in 1975, most secondary colleges in Tasmania had
either a DEC PDP system on campus, or had a terminal
connected to the main DEC system in Hobart. At Hellyer
College our computer was a DEC PDP-8/E, one of the most
popular minicomputers ever made. 12 bit data word, 15 bit
addressing, 8K of wide core memory.
A DEC core memory
Of course the computer was wont to crash quite
frequently. The process to install the BASIC interpreter
involved loading a sequence of machine code instructions via
the toggles on the front panel and then waiting for a very
large roll of paper tape on which the program was stored to
be read in. We'd wait patiently for some 30 minutes and then
hold our breath as the tape finished being read. If
successful a configuration dialog would begin to clatter out
on the Teletype. Unfortunately, it often didn't and we had
to start the process again!
Our terminal was a Teletype ASR-33, the classic
all-around I/O device. Capable of printing a blazing (for
its time) 10 characters per second (upper case and symbols
only), generating input at the same speed from keyboard or
it's built in punched paper tape reader, and punching paper
tape for output and storage at the same speed.
We could even start and stop the paper tape reader or
punch by command from the host computer which accounted for
the "ASR" (Automatic Send & Receive)
designation in it's name.
Yes, we stored our programs and read
them back in via paper tape! You could tell those doing
"Computer Science" easily as they were the ones
walking around with a show box or lunch box in which they
stored their paper tapes carefully rolled up and secured
with an elastic band.
Using the Computer
Time on the DEC PDP-8/E minicomputer was much sought after. Thus we
rejoiced when the college obtained a second Teletype
terminal. Two of us on the computer at once! Of course the
down side was we had to split the 8K of memory between two
users. The policy was a 70/30 split.
Of course many of us were already having a lot of trouble
trying to fit our more advanced programs in to 8K of
memory. To work on such programs meant going through the
process of reloading the BASIC interpreter and answering the
setup dialogue so as to only have one Teletype. When
finished, of course you had to go through the process again
so as to leave the system configured the way you found it.
But we were programming! We had access to a computer! And
you never forget your first!
Tuesday, 02 June 2009