Arbitrary-precision Arithmetic - History

History

IBM's first business computer, the IBM 702 (a vacuum tube machine) of the mid 1950s, implemented integer arithmetic entirely in hardware on digit strings of any length from one to 511 digits. The earliest widespread software implementation of arbitrary precision arithmetic was probably that in Maclisp. Later, around 1980, the operating systems VAX/VMS and VM/CMS offered bignum facilities as a collection of string functions in the one case and in the languages EXEC 2 and REXX in the other.

An early widespread implementation was available via the IBM 1620 of 1959-1970. The 1620 was a decimal-digit machine which used discrete transistors, yet it had hardware (that used lookup tables) to perform integer arithmetic on digit strings of a length that could be from two to whatever memory was available. For floating-point arithmetic, the mantissa was restricted to a hundred digits or fewer, and the exponent was restricted to two digits only. The largest memory supplied offered sixty thousand digits, however Fortran compilers for the 1620 settled on fixed sizes such as ten, though it could be specified on a control card if the default was not satisfactory.