The Citizen 830R calculator, introduced in 1976 by Citizen Business Machines Inc., is a robust and versatile device that combines functionality with a sleek design. This calculator is notable for its sturdy construction and reliable performance, making it suitable for both desktop and handheld use.
Physical Characteristics
The Citizen 830R measures approximately 87mm in width, 150mm in height, and 33mm in depth, with a weight of 198g excluding batteries. It is powered by a 6V rechargeable battery pack consisting of 4 x AA size batteries. The calculator also accepts an adaptor/charger (CTZ-800R) through a socket on the top side. The on/off switch, located on the left side, offers three positions: DC, Off, and AC. The battery compartment is easily accessible, similar to any disposable battery calculator.
Case and Display
The calculator features a two-piece light and dark grey smooth plastic case. The green plastic display filter has a frosted border and is prominently tilted. Below the display are two metallic stickers printed in black, indicating the brand and model number, as well as the memory switch positions. The keyboard surround is a brushed aluminum panel, slightly raised, with large soft-touch keys that provide a soft metallic click upon return.
The display is an 8-digit green Vacuum Fluorescent Display (VFD) with an additional symbol cluster on the left for negative, memory, and error indication.
Features
The Citizen 830R offers standard four functions with percentages, change sign, square root, squares, and a four-function memory. It also includes an additional switch for memory accumulation.
Components and Construction
The calculator is equipped with the following components:
- 1 x CPU: NEC µPD946C R61726 (date code 1976), 28 pin DIL, 0.6″ width black plastic
- 1 x 8-digit VFD with symbol cluster display flat face single tube: Futaba 9-ST-04 6C (March 1976)
- 2 x transistors
- 7 x diodes
- 7 x capacitors
- 8 x resistors
- 2 x resistor arrays
- 1 x transformer: DCT-31 Zebra
- 1 x rechargeable battery pack
The keyboard assembly (GICO GK 132-2 830R-A PPB946 K-2 51-3-13) (date code 13 March 1976) sits above the battery compartment and is attached to the main board (830R-B) (second revision) below with a 14-way ribbon cable. The calculator is held together by internal lugs, making it easy to disassemble by prizing off an edge at the bottom first, then the bottom and traveling up both sides.
Logic
- (CE) is used to cancel the last number entered, and (C) to clear the whole calculator.
- There is automatic constant on all four functions.
- Input overflow is not suppressed; inputting a ninth digit causes an overflow error, which is recoverable by dividing by ten.
- Negative numbers are shown with a “-” in the far left symbol cluster, allowing full eight-digit negative numbers.
- Overflow shows the result with “l” in the upper far left symbol cluster and is recoverable by dividing by multiples of ten.
- Divide by zero shows zero and “l” in the upper far left symbol cluster and is not recoverable.
- The change sign function can be used in mid-number entry but not before.
- Negative square roots are allowed and result in a negative number.
- Memory store is indicated by a “M” in the lower far left symbol cluster.
- An automated accumulation mode for the memory can be switched on, which only adds the result of a multiplication or division on the press of the equals key.
- An overflow in memory is not flagged as an error until you try to recall the memory, where the shifted end result is restored.
Summary
The Citizen 830R calculator is a well-built and reliable device that offers a range of features suitable for various mathematical tasks. Its sturdy construction, intuitive design, and comprehensive functionality make it a valuable tool for both desktop and handheld use. Despite its age, the Citizen 830R remains a testament to the quality and innovation of Citizen Business Machines Inc.
