The Commodore C110 calculator, introduced in the early 1970s, marked Commodore Business Machine’s inaugural entry into the calculator market. This robust device, manufactured in the USA, is a rebranded Bowmar 901B and shares similarities with the Craig 4501. The calculator’s dimensions are approximately 76mm (W) x 132mm (H) x 31mm (D), and it weighs around 320g, including batteries.
The C110 is encased in a sturdy, two-piece plastic shell, with a dark and light stippled finish. The heavily inset, tilted red plastic display filter ensures a bright and wide-angle view of the digits. Below the display, a small metallic sticker bears the brand and switch label. The keyboard surround is a metal panel with an embossed label for the constant switch, and the keys are short-travel, clicky “Klixon” type. The back of the calculator features a large panel with basic instructions.
Powered by a 9V DC internal rechargeable battery, the C110 also accepts an adapter/charger through a top-side socket. Notably, the calculator has a power-save function that activates after about 15 seconds in portable mode, switching off the display to conserve energy. The display itself is an 8-digit LED with no lens, and a ninth digit serves as an indicator for power save, input overflow, overflow, and low battery.
The C110 offers standard four-function capabilities with a switched constant and power down display recovery. It operates using Reverse Polish Notation (RPN) logic. The calculator’s components include a CPU, two Texas 75492N 7204A ICs, nine one-digit red LED displays, and two additional ICs with numerous other components. The main CPU board (PM901-400/E) is attached to the Klixon keyboard assembly and front with ten screws, soldered together with 15 wires in a plastic block, making repairs challenging.
Disassembly involves removing two screws on the rear, hidden beneath a metallic sticker that states “Removal Voids Warranty.” Inside, a substantial six AA-sized rechargeable battery pack is screwed to the rear.
Logic:
- (CE) cancels the last entry, while (C) clears the calculator.
- Input overflow is not suppressed; keying in a ninth digit results in an overflow, displaying “E” in the far left (ninth) digit.
- Overflow displays “[]” in the far left (ninth) digit.
- The logic is Reverse Polish Notation: to calculate 2-3, key in (2)(+=)(3)(-=).
- There is a switched constant function for multiply and divide only.
- After about 15 seconds, the display shows only “-” in the far left (ninth) digit to conserve power when running from batteries. Using the (D) key recovers the display or continues the calculation.
- A low battery power indicator displays “L” in the far left (ninth) digit.
The Commodore C110 calculator is a durable and well-constructed device that employs RPN logic and offers basic four-function capabilities. Its power-saving features and robust design make it a notable entry in the history of Commodore’s calculator lineup.
