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 and 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 boards in this LOCI-2A calculator are:
1501 Input Decoder Control for the Card Reader and Teletype
1401A Register Decoder and NIXI Display
1402A W-Register with Binary Adder
1403B L-Register with Binary Adder
1404A Main Timing
1405A Miscellaneous Shift Pulse and Control
1406A A-Register with Accumulator, Decimal Counter
1408A Program and Decrement Counters plus Storage
No connectors or wiring harness
1410A 16 S-Registers Containing 10 Digit Decimal + Sign of Each Register (Core)
There are a few LOCI-2 calculators left, most in private collections. These are the public ones:
#2789, LOCI-2 Model 2A, Computer Museum of America including documentation and spare boards
#2814, LOCI-2 Model 2A, RICM
#2856, LOCI-2 Model 2AD, The Computer History Museum
#3010, LOCI-2 Model 2AD, DOPECC (Dawn of Personal Electronic Calculators and Computers)
#3026, LOCI-2 Model 2AC, RICM
#3059, LOCI-2 Model 2A, Michael Dunn's Museum of Calculators and Other Oddities
#3086 LOCI-2 Model 2A, Old Calculator Museum
#????, LOCI-2 Model ?, Living Computer Museum has three non-functional LOCI-2
Wang LOCI-2 Model 2A