The 1401 mainframe that brought computing to the business community has just celebrated its 50th birthday, writes KARLIN LILLINGTON

IN OLD pictures, an IBM 1401 mainframe – the original “Big Iron” – looks exactly like a cartoon image of a computer: refrigerator-sized, boxy, flashing lights on a panel, big reel to reel tape spools on the front.

And for good reason. The 1401, which has just celebrated its 50th birthday, was one of the most iconic and successful computers ever built, even featuring in a scene in the film Dr Strangelove.

This also is the machine that brought computing to the business masses. One of the very first computers to be used widely for business applications, it put modern computing within reach of small to medium-sized businesses when it was launched with fanfare in 1959 in six memory configurations, from 1.4k to 16k.

The monthly rental for a machine ran from a relatively affordable $2,500 depending on the configuration, and many smaller clients used bureau services from IBM to have them run business processing jobs on computers housed and maintained by IBM.

Its ability to use magnetic tape for storage rather than just punch cards enabled unheard of rates of processing – up to 41,000 characters could be read per second, and a single reel, with 2,400ft of tape, could store data the equivalent of 400,000 punchcards.

Within just two years, 2,000 were in use in the US – accounting for one in four of all electronic computers, according to IBM – and by the middle of the decade, 10,000 clattered away in special air-conditioned rooms, attended to by technicians and programmers in white shirts and ties.

The IBM 1401 was also one of the very first computers to come to Ireland, and though few companies were large enough to have one or more of their own (the ESB, Aer Lingus and the post office, for example), business customers in the 1960s could have IBM run their jobs on its 1401 in offices at 28 Fitzwilliam Place.

Retired IBM programmer, systems analyst and machine operator Denis Mullen recalls his first sight of the 1401, having been allowed a glimpse during his interview process in 1966.

“Oh, absolutely awestruck! They had said: ‘You must come down and see the computer.’ It was in its own air-conditioned room and looked very exciting. A man in a white shirt and tie was there feeding cards into it and lights were flashing, and there was movement. He asked if I wanted to feed in some of the cards. It was like lifting a newborn baby!”

Mullen was a recent UCD science graduate looking for a job and when he saw an advertisement in the paper for a machine operator position at IBM, he applied immediately.

“I read a book somewhere along the way on programming,” he laughs.

“The idea of working with these computers seemed very attractive and it was a way of getting into computing.”

He got the job and soon worked his way up to being a 1401 programmer and then system analyst, going on to a 36-year lifetime career with Big Blue.

He says that this was “the era of the space age and science and technology was very cutting edge and you felt you were contributing to the development of the Irish economy after the stagnation of the 1950s”.

Mullen recalls the Fitzwilliam Place 1401, a 12k computer, as a very reliable, sturdy machine without quirks, “incredibly solid, it basically just worked”.

But everything to do with the 1401 was special – even the servicing man arrived in a suit, then removed his jacket and put on a white coat to get down to work.

The operators and programmers worked in what had formerly been the private chapel attached to the Fitzwilliam Place nobleman’s townhouse, still with its stained glass and religious carvings.

“I won’t say you felt it was a sacred duty, but it added to the mystique!” He recalls the basement of the building was filled with the women who created the punch cards for the various contract jobs.

“Going to the basement was a great opportunity to meet the ladies,” he says.

A popular service was to use the 1401 to supply monthly or weekly accounts to clients – “everyone wanted that” – but they also kept track of deposits for building societies and mortgage payments for mortgage firms, and did stock accounts for big companies like Roadstone, all run on very tight weekly work schedules. If anything went wrong with the machine “there would be a huge drama”.

It rarely happened, but Mullen remembers a team of technicians would be rushed over to examine the machine with their oscilloscopes, much like ministering doctors.

He enjoyed learning programming: “Terribly creative; your program was your work of art. And different personalities wrote different types of programs. It was quite challenging and very satisfying.”

IBM retired the 1401 in 1971 and Mullen went on to work with the IBM 360 series and other computers throughout a long career, but the 1401 was his very first and holds a special place.

“It was very exciting to be part of that – the sheer magic of it,” he says.