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IBM 1400 series

From Alfawiki
IBM 1400 series
Company typeProduct line
IndustryComputer hardware
FoundedOctober 5, 1959; 67 years ago (1959-10-05)
FounderInternational Business Machines Corporation (IBM)
Headquarters
Armonk
,
United States
ProductsMid-range business decimal computers (IBM 1240, 1401, 1410, 1420, 1440, 1450, 1460, 7010)
ParentIBM

The IBM 1400 series represents a line of second-generation mid-range business decimal computers utilizing transistor technology, introduced by IBM during the early 1960s. These machines were engineered to succeed tabulating machines such as the IBM 407. Data was maintained in magnetic core memory as variable-length character strings, delineated by special markers known as "wordmarks" and "record marks." Arithmetic operations were conducted on a digit-by-digit basis. Input and output capabilities encompassed punched card, magnetic tape, high-speed line printers, and early models of disk storage.

Several models operated independently, while others served as enhancements to IBM punched-card equipment or functioned as auxiliary processors for other computing systems. Certain versions were customized for particular applications or optimized for standalone performance.

History

The initial and most widely adopted system in the series was the IBM 1401, released on October 5, 1959, with sales exceeding 10,000 units. The IBM 1410 shared a similar architecture but offered an expanded address space. The IBM 1460 provided increased speed and additional options, featuring 16,000 characters of memory capacity. The IBM 1240 was designed specifically for banking environments with MICR capabilities, while the IBM 7010 mirrored the 1410’s design but operated at twice the speed.

Notable models within this lineup include:

  • IBM 1240 - Banking system introduced in 1963
  • IBM 1401 - Released in 1959
  • IBM 1410 - Launched in 1960
  • IBM 1420 - Introduced in 1962 as a high-speed bank transit processor capable of handling up to 50,000 checks per hour
  • IBM 1440 - Debuted in 1962
  • IBM 1450 - A banking data processing system for smaller institutions, introduced in 1968
  • IBM 1460 - Released in 1963
  • IBM 7010 - Available from 1962

Typical peripherals associated with the series included:

Compatible systems

Several IBM models were designed to be compatible or nearly so with the IBM 1401:

  • The IBM 1460, which operated at double the speed and incorporated numerous standard features from the 1401.
  • The IBM 1440, a cost-effective alternative that was popular but did not offer full compatibility.
  • Banking-focused systems such as the 1240, 1420, and 1450.
  • The IBM 1410, which provided enhanced performance with expanded memory (up to approximately 100,000 characters), more index registers (fifteen), and additional instructions; it included a "compatibility mode" enabling execution of unmodified 1401 programs.
  • The IBM 7010, a faster system fully compatible with the IBM 1410.
  • The IBM System/360 Model 30 featured an optional microprogram to support compatibility with the IBM 1401; various peripherals from the IBM 1400 series were adapted for use with System/360.

Honeywell’s Honeywell 200 also offered approximate compatibility with the IBM 1401 through architectural similarities and software support.

Field and character coding

Within the IBM 1400 series architecture, the smallest unit addressable in core memory is a single character. Internally, characters are encoded in binary-coded decimal (BCD) format using six bits (BA8421). When used to represent operation codes or indicate the start of a field, an additional "word mark" bit is incorporated alongside an odd parity bit labeled "C."

Arithmetic operations are performed on decimal values following a big-endian convention: multi-digit fields have their least significant digit stored at the lowest memory address. Instruction address fields have fixed lengths determined by memory size; however, numeric operands can vary arbitrarily in length. The use of word marks enables flexible access to fields from either end, facilitating efficient operand manipulation. This architecture necessitates that compilers handle adjustments to operand addresses during arithmetic instruction processing.

Programming languages

The 1400 series supported several programming languages, including Symbolic Programming System (SPS), which functioned as an assembly language, and Autocoder, a more sophisticated assembly language variant. Additionally, languages such as COBOL, FORTRAN, Report Program Generator (RPG), and FARGO were also available for use with these systems.

Retirement

Following the 1400 series, IBM introduced the System/360, which was eventually complemented by a range of lower-end machines including the IBM System/3, System/32, System/34, System/36, System/38, and AS/400.

Despite being officially discontinued in the early 1970s, certain peripherals from the 1400 line continued to be sold alongside third-generation computer systems.

At present, two restored 1401 machines remain fully functional and are on display at the Computer History Museum.

References

External links

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