The first member of the highly successful IBM 1400 series, it was aimed at replacing unit record equipment for processing data stored on punched cards and at providing peripheral services for larger computers.

[1] The 1401 is considered by IBM to be the Ford Model-T of the computer industry due to its mass appeal.

"IBM was pleasantly surprised (perhaps shocked) to receive 5,200 orders in just the first five weeks – more than predicted for the entire life of the machine!

"[6] By late 1961, the 2000 units installed in the USA were about one quarter of all electronic stored-program computers by all manufacturers.

[7] Commonly used by small businesses as their primary data processing machines, the 1401 was also frequently used as an off-line peripheral controller for mainframe computers.

It was the 1401 that transferred input data from slow peripherals (such as the IBM 1402 Card Read-Punch) to tape, and transferred output data from tape to the card punch, the IBM 1403 Printer, or other peripherals.

Some later installations (e.g., at NASA) included the 1401 as a front-end peripherals controller to an IBM 7094 in a Direct Coupled System (DCS).

Elements within IBM, notably John Haanstra, an executive in charge of 1401 deployment, supported its continuation in larger models for evolving needs (e.g., the IBM 1410) but the 1964 decision at the top to focus resources on the System/360 ended these efforts rather suddenly.

IBM pioneered the use of microcode emulation, in the form of ROM, so that some System/360 models could run 1401 programs.

[10]Due to its popularity and mass-production, the IBM 1401 was often considered to be the first electronic mainframe computer to be introduced in various countries, such as Singapore (1963; for the Central Provident Fund Board)[11] and South Korea (1967; for the Economic Planning Board).

Two 1401 systems have been restored to operating order at the Computer History Museum in Mountain View, California.

Associated with each memory location are two other bits, called C for odd parity check and M for word mark.

The zone bits of the high-order character specify an increment as follows: A 1000, B 2000, B and A together 3000, giving an addressability of 4,000 memory locations.

The zone bits of the low-order character specify increments of 4000, 8000, or 12000, to address 16,000 memory locations (with an IBM 1406 Storage Unit).

The zone bits of the middle character of a three-character memory address can specify one of three index registers, one of many optional features.

When an operation such as addition is performed, the processor begins at the low-order position of the two fields and works its way to the high-order, just as a person would when adding with pencil and paper.

Typical logic levels of these circuits were (S & U Level) high: 0 V to -0.5V, low: -6 V to -12 V; (T Level) high: 6 V to 1 V, low: -5.5 V to -6 V. These circuits are constructed of discrete components (resistors, capacitors, transistors) mounted on single-sided paper-epoxy printed circuit boards either 2.5 by 4.5 inches (64 by 114 mm) with a 16-pin gold-plated edge connector (single wide) or 5.375 by 4.5 inches (136.5 by 114.3 mm) with two 16-pin gold-plated edge connectors (double wide), that IBM referred to as SMS cards (Standard Modular System).

The SMS cards were inserted in sockets on hinged swing-out racks, that IBM referred to as gates.

The modules used were fairly delicate, compared to previous unit-record equipment, so IBM shipped them enclosed in a newly invented packing material, bubble wrap.

In many cases, particularly for the more common instructions, the character chosen is mnemonic for the operation: A for add, B for branch, S for subtract, etc.

4000 characters of memory) Record or Group Mark and/or Zone Suppress Zeros Two of the instructions, Branch on Indicator (B) and Select Stacker (K), use a "modifier" operand.

In October 2006, Icelandic avant-garde musician Jóhann Jóhannsson released the album IBM 1401, A User's Manual through music publisher 4AD.

The album was originally written for a string quartet, organ and electronics and to accompany a dance piece by long-standing collaborator friend, Erna Ómarsdóttir.

[27] More well-known are various demo programs to play music on transistor radios placed on the CPU[28] and computer "art", mostly kitschy pictures printed using Xs and 0s on chain printers.

A truck-based IBM 1401 configured in 1960 for military use was designated a portable computer, and nicknamed a DataMobile.