1971 · Portable Electronic Calculator · Work 934 of 1,871
A sales representative's office in New Jersey on a winter afternoon, on a green leather desk pad an upright calculator sixteen centimetres tall in black plastic with rounded corners and a pale base strip, at the top a dark green-tinted window with eight small upright glass tubes glowing soft green, below in a shallow recess twelve cream keys, two pale blue keys and one red key, every key plain smooth and unmarked, a small plain silver badge beneath, a black power cord running to the wall, an open sample case of brown leather beside it, a hand with a gold cufflink reaching from the right, window light from the left.
What it was used for
Sharp introduced the EL-8, a portable battery-powered four-function calculator, in January 1971, at 345 dollars in the United States. It calculated to 8 digits with automatic floating point, showed a minus sign and ERROR on overflow, and saved keys by combining multiply and divide on one key. The display was made of separate vacuum fluorescent tubes of the Itron type from Iseden, 8 segments per digit, the zero drawn half height. Power came from a NiCd pack of 6 cells at 7.2 volts, charged through the EL-81 adapter. In the account of the Old Calculator Web Museum it was the first genuinely portable battery-powered calculator, though awkward in the hand: it fitted a briefcase, not a trouser pocket.
What was new
What was new was not the calculating circuit but its current draw. The Rockwell LSI devices (AU2271, DC2266, AC2261, NRD2256) with the CG1121 clock generator were developments of the Autonetics set from the QT-8D desktop machine and used only half the power; which significantly lengthened running time on battery power. The design was also sold under other names: the Facit 1111 and the Addo-X 9364 were technically identical. And the handling had an edge: dividing by 0 left the machine in an undefined state, to be cleared with the C key.
What the sources leave open: The source gives no weight or dimensions, and no figure for battery life, only that running time was significantly longer. Sharp's own company history for 1973 to 1975 does not mention the EL-8, so only 1 source stands behind this entry.