IBM 1401 - 1401 Culture

1401 Culture

More well-known were various demo programs to play music on transistor radios placed on the CPU and computer "art", mostly kitschy pictures printed using Xs and 0s on chain printers.

The 1401 was made before FCC rules came into effect limiting unintentional radiation from electronic devices. As a result the 1401 would radiate signals covering the entire AM radio band. This had some utility as an AM radio placed on top of the computer would emit a stream of audible notes until the program ended, at which time the sounds would stop. This allowed a solo operator of a 1401 to do other work until they were needed to start another program. Each operation transmitted a specific note, thus allowing someone to put together music by executing the right op codes in a specific order. As an operator this also had the effect that specific jobs would play the same musical notes when then run. For example, an operator familiar with the sounds could easily identify an Autocoder compiler execution from a payroll job based on the sequence of notes.

Another feature of the 1401 was small muffin fans that blew cool air into the bottom of each gate, up around the electronics and out the top. It was common to take two standard IBM punch cards, stapled together into a circle, and with the top cut and folded over, and place them over the air stream from a fan. The cards would stay centered on the air stream and spin round and round as the computer operated. This allowed operators to check at a glance from outside the room whether the computer was operating or not based on the motion of the cards.

The simplicity of the 1401 made it, if not a modern ruggedized machine, fairly reliable in stressful conditions. Thus IBM 1401 systems were more extensively used for US military logistics applications, in Vietnam and elsewhere, than were other, more advanced, systems.

During the 1970s, IBM installed many 1401s in India and Pakistan where they were in use well into the 1980s. Some of today's Indian and Pakistani software entrepreneurs started on these 1401s. The first computer in Pakistan, for example, was an IBM 1401 installed at Pakistan International Airlines.