Computer History Of The World, Part 5

by Bob Seidel

I haven't run a continuation of my computer history thread since last November, so I think it's a bit overdue. If you have lost the thread, you can pick it up in the copies of these columns on my website.

The timeframe was the late 60's and early 70's, and I was discussing the hardware of the ponderous mainframe computers that were all we had at the time. The software that was run on those computers was equally primitive by today's standard.

There were no CRT displays, or computer graphics, or multimedia applications at that time. There were no computer terminals - these did not appear in active use until a few years later. You prepared your computer job on punched cards, using a card punching machine that looked like a very large electric typewriter. Sometimes, it was harder to get time on the card punch machine than it was to get time on the computer itself!

Everybody carried around long boxes of these punch cards - some boxes were (a bit) stylish and resembled long briefcases. Others were metal and some people just used the cardboard boxes that the blank cards came in. Sometimes you had so many boxes of cards that you needed a little cart to carry them on.

The large mainframe computers that I worked on used an Operating System called OS/MFT. MFT stood for Multiprogramming with a Fixed number of Tasks. Using this OS, you would partition the RAM of the computer into a fixed number of partition areas, each of which could run one job at a time. Since there wasn't much RAM available (our 360/70 mainframe had only 512 kilobytes), that meant you couldn't run too many jobs at a time. An improved version called OS/MVT (Multiprogramming with a Variable number of Tasks) would assign RAM dynamically as needed to jobs, but this OS was still in testing and not stable enough for us to use.

To run a job, you brought your boxes of punched cards to a machine connected to the computer, called a Card Reader. Some of these were actually quite fast, capable of reading thousands of cards a minute. You laboriously stacked your cards into the input feeder and waited for the computer to read them in. My group was able to do this since we had "hands-on" time directly on the computer. Others weren't so lucky and had to put their card boxes in a shuttle pickup area, where they would be picked up several times a day, and returned after the job was run.

There were few computer languages in use to write your programs in - FORTRAN being the most common. We also used some specialized simulation languages when writing simulations of computers under development.

The control of the job execution process was done by another language called JCL (Job Control Language). JCL was very arcane, and only a few were true masters of it. I became one of the local masters almost immediately, thus marking me as a computer nerd for life.

As today, there were programs written by users that made up for shortcomings in the OS itself. We used one of those called HASP (Houston Automatic Spooling Program) to control the job flow into and out of the computer. HASP read the cards much faster than the OS/MFT and allowed a bit greater control in job scheduling. I believe that IBMers at NASA Houston wrote HASP. HASP also controlled the printing of output to the printers, making this more efficient.

So we would all show up at the computer center with our boxes of cards. HASP allowed the programmer to assign a priority to his job - small jobs were given higher priority - and heaven forbid if you didn't assign the right priority to your job. We would load our jobs and wait. If you didn't have the highest priority job (code 14), you would have to wait until all the higher priority jobs were finished. People with longer jobs actually became quite belligerent at times, sometimes barring the door or the path to the card reader if they say someone with a higher priority job coming in!

(Bob Seidel is a local computer consultant in the Southport / Oak Island area. You can visit his website at www.bobseidel.com or e-mail him at bsc@bobseidel.com).