Sinclair Radionics

• Sinclair

Model: Cambridge Type 2
Battery: 4 x AAA cells
AC adapter:
Year: 1973
Chip: TMS0801NC
Info: made in England

• Sinclair

Model: Executive Type 1
Battery: 4 x AAA cells
AC adapter:
Year: 1972
Chip: TMS0103NC
Info: made in England

• Sinclair
• RPN

Model: Scientific
Battery: 4 x AAA cells
AC adapter:
Year: 1974
Chip: TMS0805NC
Info: made in England

How to use this unusual calculator

The Sinclair Scientific calculator uses reverse Polish notation (RPN) and scientific notation, so the key sequences are totally different from regular calculators. Numbers automatically have a decimal point inserted; use E to set the exponent. Operations are entered after the number and there is no equals key. Use the up and down arrows to select scientific functions. A display such as 1.2300 01 indicates 1.23*10^1, i.e. 12.3. A few examples:

To divide 17 by 3, enter 1 7 E 1 + 3 ÷

To take the sin of 0.01 radians, enter 0 0 1 ▲ +

To take antilog of .5 (to compute 10^.5), enter 5 E - 1 ▼ ×

Reverse Engineering from Ken Shirriff's blog