IBM System/3 - Quirks

Quirks

The System/3 had no provision for halting a process once it had started to run. For instance, if a compile failed because of an error on the very first page, you had to wait for a sometimes voluminous compile listing to print in its entirety. One trick learned by programmers was that you could reach under the printer and jostle the paper discharge chute. This would cause the machine to halt and an error code P3 would be displayed on the console. You could then dial in the code FF to abort the run.

The System/3 also had no audible warning device, so a program could halt and unless the operator was looking at the console and noticed the status lights showed the Error Code he often did not realize that an event had occurred and the machine was not operating. Error codes were displayed on one of the first seven-segment displays (2 digits) ever seen, built with lamps rather than LEDs. Models with the Dual Program Feature had two separate status display.

Most/many users did not buy a console. Instead OCL code was either suppressed entirely or printed on the 5203 printer. The console offered by IBM slowed down program execution tremendously when it printed OCL commands, as it was basically a selectric typewriter.

The concept of keying your punched cards through the console was a marketing ploy. In reality, the System/3 could not be a computer and a keypunch at the same time, so when it was a keypunch, no computing was possible. The original IBM System/3 which was shown in July, 1969 had the keypunch console so they could offer a computer for under $2,000/month. In reality it was unworkable and almost invariably users acquired a stand-alone keypunch/verifier.

Later several OEM companies built 96 column keypunches, sorters, collators. This took the 'heavy lifting' off of the MFCU and freed the System/3 for actual computing functions.

Most experienced System/3 users minimized use of the MFCU as much as possible, since it was a system bottleneck.