NCR 18-15 Desktop Calculator
Image Courtesy Ian Ormerod
The NCR 18-15, designed
and manufactured by Nippon Calculating Machine Co.(NCM) (also known as Busicom)
and licensed to NCR for sale under the NCR brand name. The 18-15 was the first
easily portable desktop AC-powered calculator marketed by NCR. The unique
design of the machine managed to cram the calculating brains onto three circuit boards containining only 22 integrated circuits. This was due to higher
levels of integration (Medium-Scale integrated circuit devices), and clever packaging.
The 18-15 was a 12-digit, vacuum-fluorescent display calculator, with fixed
decimal point settings (slide switch), and the basic four math functions.
The architecture of the 18-15 served as the design basis for a single-chip
calculator IC made by MOSTEK (the first ever successful calculator-on-a-chip),
which resulted in the follow-on to the 18-15, the NCR 18-16, a machine virtually identical functionally and visually, but was about 1/2-inch thinner, and slightly slower than the 18-15 due to the use of the early MOS (Metal Oxide Semiconductor) LSI (Large-Scale Integration) calculator chip.