Wang LOCI-2A Calculator Logarithmic Calculating Instrument

The Wang LOCI-2 Programmable Calculator was introduced in January 1965, replacing the LOCI-1 that was introduced just four months before. The LOCI-2 has more than 1,000 transistors, no integrated circuits, core memory, and NIXIE Tubes for the display. To dramatically improve the speed of multiplying amd dividing it actually added or subtracted logarithms. It supported a printer, Teletype, and punched card reader peripherals.

This LOCI-2 is a model 2A, so it has 16 Storage Registers instead of 4 on the model 2, and no I/O interfaces.

This LOCI-2. #2814, was donated by Tom and Ingrid Barry. It was originally purchased by the GTE Sylvania Lighting Products Group in Danvers, Massachusetts.

Numbers are stored in the registers in Binary Coded Decimal format. There is a 1, 2, 4, and an 8 bit for each digit in a number. The decimal value of a digit is the sum of the bits for each weight, e.g. a 9 is stored as a 1 and an 8. Each bit is stored in a flip-flop made from two transistors. Most registers are 10 digits wide, so it takes 2 x 4 x 10 = 80 transistors to make a register.

The restoration blog is here.

There are two LOCI-2 Model 2A Calculators at the Old Calculator Museum, #3070 and #3086, and a LOCI Printer. There is a LOCI-2 Model 2AB calculator at the National Museum of American History, #2734, and a card reader. There is a LOCI-2 Model 2A at Michael Dunn's Museum of Calculators and Other Oddities, #3059. The RICM also has a LOCI-2 Model 2AC calculator, #3026.

Wang LOCI-2 Model 2A