The Brother 827R is a handheld calculator from 1974. It measures about 78mm x 127mm x 17-22mm (width, height, depth) and weighs 150g without batteries. The case is two-piece smooth plastic in a cream color, with grip ridges on the sides for easy handling. A large red display filter wraps around the front to improve readability of the small digits on the 8-digit LED display. An additional LED indicates when memory is in use.
Inside, the 827R contains a Texas Instruments TMS0603 processor chip, two SN75494 display driver chips, a 9-digit bubble lens LED display, two transistors, five diodes, six capacitors, no resistor arrays, 11 resistors, and a transformer. The keyboard connects to the main circuit board via 17 wires.
Power comes from three AA batteries or an optional AC adapter. Rechargeable NiCd batteries can also be used. Functions include the four standard arithmetic operations, percentages, and a 4-function memory with summation mode. Automatic constant, input overflow suppression, and overflow/error indication are implemented in the logic. There is no squared function.
In daily use, the 827R feels well-built, with nice “clicky” keys. The two-step clear button and summation switch add convenience. Downsides include the small display, lack of squared, and some unrecoverable errors. But overall the 827R provides the expected features for a mid-1970s handheld calculator in an easy to use package.
