The IBM 1401

The first relatively affordable and widely popular mainframe, the IBM 1401 Data Processing System has been called “the Model T of the computer industry.” Just as Henry Ford introduced the automobile to the masses, the IBM 1401 opened the information age to thousands of small and medium-size businesses. It changed the construct and outlook of the computer industry, from design to production to use.

Introduced in 1959, the IBM 1401 quickly made inroads into the business community. By the mid-1960s, it comprised more than half of the world’s computers. The 1401 family spawned an entire generation of programmers who first learned computing on these machines.

There were several keys to the 1401’s popularity. One was affordability. The 1401 could be leased for as little as USD 2,500 per month — at a time when comparably equipped computers leased for USD 10,000 per month and large mainframes cost more than USD 1 million to purchase outright. The 1401 was also considered a real value because of its advanced technologies. It was one of the first computers to run on transistors instead of power-hungry and fragile vacuum tubes, making it far more reliable and compact than existing mainframes. To input and store data, the 1401 could accommodate both the widely used punched cards and the newer magnetic tape, which could accelerate data storage and retrieval.

The 1401 changed perceptions among business executives. A computer didn’t have to be as big as a room and at the service of just large corporations — it could fit comfortably in the office of a medium-size company or lab, and each department could afford to have one of its own. The 1401 convinced enterprises of all sizes that a computer was essential to their daily operation. It also spurred IBM and other technology companies to scale up production for a future defined by computing.

IBM scrambled to develop a machine to meet the demand. In the mid-1950s, French computer upstart Machines Bull released its Gamma computers, which were small and fast compared with goliaths like the IBM 700 series. The Gamma line prompted IBM and others to realize that organizations with smaller budgets had a use for computers. During the summer of 1957, IBM engineers and planners gathered in Germany to propose several new accounting machine designs. The anticipated product of a seven-week conference was known thereafter as the Worldwide Accounting Machine (WWAM).

In September 1957, IBM’s Charles Branscomb was assigned to run the WWAM project. In March 1958, after Thomas J. Watson Jr. expressed dissatisfaction with the WWAM project in Europe, a proposal for a stored-program computer was given formal approval to meet IBM’s need for an electronic accounting machine. Big developmental challenges needed to be addressed, namely to conceive an architecture devoid of the plugboard, a spaghetti-like array of cords and plugs that told a computer what to do.

Plugboards dramatically slowed computing because they required a complete rewiring by a skilled programmer for each new program. Underwood succeeded in eliminating the plugboard control panel entirely and designed a “stored program computer,” which enabled programmers to write and share applications loaded into the machine from punched cards or magnetic tape, all without physically reconfiguring the machine.

The 1401 System would consist of three components — a central processing unit that controlled all computational functions, an input/output device known as the 1402 Card Read-Punch that could read up to 800 punched cards per minute and punch 250 cards per minute, and the high-speed 1403 printer that could print 600 lines of text per minute. The 1401 could transfer input data from cumbersome punched cards to faster and less bulky magnetic tape drives, and many used the 1401 to make the switch from cards to tape.