All electronic and logical operations of the printer are under the stored program control of the 1401 Processing Unit. It’s easy to sort records if you can read all the data into memory, sort it and write it out, but not so easy when only a few records will fit in memory at one time.The 1401 was certainly not the biggest computer on the block when it was introduced, but the focus on modest cost and compatibility with existing business processes made it a very successful machine. Both machines started out under lease from IBM to insurance companies, and both escaped the crusher by being sold second-hand into home businesses. IBM 1401 Processing Unit This unit controls the entire system by means of its stored program. Speed: In one minute, the 1401 Processing Unit can perform 193,300 additions (eight-digit numbers) or 25,000 multiplications (six-digit numbers by four-digit numbers). This is equivalent to a printing speed of 4,800 lines per minute. Robert Garner’s IEEE “The Legendary IBM 1401 Data Processing System” 1 A “card deck” is a term-of-art for what an ordinary person would call a stack of punched cards.
2 The 1401 used decimal (not binary) addressing, so 16K really means 16,000, not 16,384. While many I/O devices were added during the 1401 family’s lifetime, the machine started out with only three:The 1401 doesn’t have a keyboard or display, so how would all that important business data get into the computer in the first place? The larger system is thus made available for data processing and logical operations. The 1401 could read the data from punched cards, but where did they come from? CHM’s 1401 Demo Lab actually contains two independent machines. The keypunch operates as a typewriter, punching everything the operator types into the body of the card as patterns of holes. A feature of the Printer is a wheeled form stand which reduces and simplifies paper handling. But the 1401 would have been the cheapest, priced to appeal to ordinary businesses that simply wanted to run their finance and accounting systems more efficiently, and in particular, to replace single-purpose electromechanical machines that used levers, knobs and plugboards to program their operations.By the time the 1401 was introduced, electromechanical systems based on punched cards were widely used to manage business operations. The computers were offered to replace tabulating machines like the IBM 407 . IBM TS7700's grid communication facility provides access from any host to all data in the grid, supporting superior business continuance. Some keypunches also printed the typed characters along the top edge of the card, but many operators became adept at reading the patterns of holes directly.Keypunches were a mainstay of the data processing industry long before the 1401 came along, as operators would transcribe data to punched cards for existing card sorters and tabulating gear. Alphabetical or numerical data may be processed. For the businesses that used these machines, the 1401 marked the end of rooms full of single-purpose business machines programmed with plugboards and mechanical controls, to be replaced by universal machines programmed via the powerful stored-program paradigm. The 1403 prints by means of a scanning operation which compares characters on the chain with characters in storage designated to be printed. Many characteristics are still very familiar, but some are quite different because of the focus on the “unit record”1 one-punched-card-at-a-time paradigm. We’ve all heard it: “Today, your phone has a zillion times more processing power than giant computers that filled an entire room in days past!” Rather than review bits and bytes, let’s look at CHM’s 1401 computer from the point of view of what it can do, and its long-lasting impact on the development of business computing.At its introduction in 1959, the 1401 was not the largest computer on the block; for IBM, that would have been the massive 7090 scientific mainframe, introduced a year earlier, followed by the even-larger STRETCH supercomputer in 1961.
Thousands were sold, and by 1965, half of all computers in the world were of the 1401 family, spawning an entire generation of programmers who first learned computing on these machines. Information to be printed is read into storage from the input cards or magnetic tape, processed, and read out to the Printer.