A student room in Boston on an autumn evening, a white short-sleeved shirt hung over the back of a wooden desk chair, from its breast pocket the upper half of a small hand-held calculator rising beside two ballpoint pens, a body of charcoal-grey plastic eight centimetres wide, at its top a dark red-brown tinted window under a projecting rim with a faint soft red glow, below it a plain brushed silver strip and a brushed silver key plate with square black keys and one red key, all plain smooth and unmarked, a desk lamp casting warm light from the left, red maple leaves at the dark window.
What it was used for
The Bowmar 901B is a pocket calculator with an LED display. Its maker, Bowmar/ALI of Acton, Massachusetts, was a small defence supplier that really wanted only to sell LED displays. When that failed in the calculator market, the company decided in 1970 to build a hand-held machine itself. The basis was TI's TMS0103 chip, with Klixon keys from TI. It cost 240 dollars and measured 3.1 × 5.2 × 1.5 inches. It was also sold under other names: Craig as model 4501, Commodore as the C110; later Bowmar machines went out as house brands of Sears and RadioShack.
What was new
According to IEEE Spectrum the 901B is generally regarded as the first calculator with an LED display and the first of pocket size; the ground had been laid by Monsanto, which in 1968 produced the first numeric LED display cheap enough for consumer goods. Success was brief: Bowmar/ALI was for some years in the early 1970s the largest calculator maker in the world and brought out about 28 models in 5 years, and then prices fell. In mid-1974 a basic handheld calculator typically cost around 179 dollars; by the end of the year cheaply built machines with fewer features were offered for as little as 15 dollars. On 10 February 1975 Bowmar filed for Chapter XI protection, after a loss of 20 million dollars in the 1974 financial year and with roughly 35 million dollars of loans outstanding.
What the sources leave open: IEEE Spectrum states explicitly that sources disagree on the year of release (1971 or 1972) and dates the bankruptcy to 1976; the Chapter XI figures are in the Old Calculator Web Museum's own text accompanying a Radio Electronics item of May 1975. Neither source gives unit sales. The HNF dates the Busicom LE-120A with an LED display to January 1971, so the 901B's priority is doubtful.