Editing Arbitrary-precision arithmetic (section)

==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 1 to 511 digits.  The earliest widespread software implementation of arbitrary-precision arithmetic was probably that in [[Maclisp]].  Later, around 1980, the [[operating system]]s [[VAX/VMS]] and [[VM/CMS]] offered bignum facilities as a collection of [[literal string|string]] [[subprogram|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 table]]s) 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 60 000 digits, however [[Fortran]] compilers for the 1620 settled on fixed sizes such as 10, though it could be specified on a control card if the default was not satisfactory.