This HP-87XM Desktop computer was donated by Carolyn Faiola of Rhode Island. The Hewlett-Packard series 80 of small scientific desktop computers was introduced in 1980, beginning with the popular HP-85 targeted at engineering and control applications. They provided the capability of the HP 9800 series desktop computers with an integrated monitor in a smaller package including storage and printer, at half the price.


The machines were built around an HP-proprietary CPU code-named Capricorn running at 625 kHz (

0.6 MHz, sic) and had a BASIC interpreter in ROM (32 kB). Programs could be stored on DC-1

00 cartridge tapes or on external disk/tape units.

Despite the comparatively low processor clock frequency, the machines were quite advanced compared to other desktop computers of the time,[3] in particular regarding software features relevant to technical and scientific use. The standard number representation was a floating point format with

a 12-digit (decimal) mantissa and exponents up to ±499. The interpreter supported a full set of scientific functions (trigonometric functionslogarithm etc.) at this accuracy. The language supported two-dimensional arrays, and a ROM extension made high-level functions such as matrix multiplication and inversion available.

For the larger HP-86 and HP-87 series, HP also offered a plug-in CP/M processor card with a separate Zilog Z-80 processo