The Commodore 7923 is a notable calculator model released in 1978. Its design, functionality, and construction reflect the late 1970s shift towards more portable and functional handheld electronics, aimed at delivering dependable computing within a small frame.
Design and Dimensions
This calculator’s dimensions measure approximately 67 mm (width) x 157 mm (height) x 25 mm (depth) at its widest points. Its total weight is around 84 grams, excluding batteries, making it a lightweight choice for users. The casing is composed of beige, matte plastic with a brushed aluminum keyboard surround, which was less common in later Commodore models. The display features a sloping red plastic filter, delivering clarity though somewhat limited in viewing angle. The keys are oblong with a distinctive “squishy-click” response, and the calculator is labeled with black print, which has held up well over time.
Power Requirements
The 7923 operates on a 9V DC power source, typically provided by a single PP3 battery. Additionally, an adapter (model DC-620R or others such as 505, 506, 507) can be connected via a socket located on the left side, aligned with the Commodore logo.
Display and Functional Capabilities
This calculator uses an 8-digit red LED display, with a ninth digit dedicated to indicators for error, memory storage, and negative values. Core functions include standard four-function arithmetic, percentage calculations, and memory capabilities, with register exchange available. While this functionality was basic, it was suitable for the needs of most general users.
Components and Internal Layout
Internally, the 7923 houses a MOS MPS 7564 102 0778 CPU, dated to the seventh week of 1978. The LED display is a single 9-digit bubble lens unit, with a diode attached to the display pins. The internal boards consist of a keyboard board and a floating CPU board, connected by a 14-way ribbon cable. Assembly involves a single screw and a series of plastic lugs, enabling secure construction while keeping disassembly straightforward.
Logic
- The (C/CE) key can be pressed once to cancel the last entry and twice to reset the calculator.
- An automatic constant applies to all four functions.
- Input overflow is suppressed, ignoring the ninth digit entry.
- Negative numbers display with a “-” symbol in the leftmost digit.
- Memory operations include recall (MR), total (MT), and memory store, indicated by a decimal point in the ninth position.
- Division by zero displays an “E” on the left, which is non-recoverable, as is overflow.
- Overflow can be stored in memory without triggering an error until recalled.
- The (EX) button exchanges the display with the last register.
- The (%) button divides by 100, simplifying percentage calculations.
The Commodore 7923 is a classic model from Commodore’s late calculator line. Though limited by today’s standards, it provided users with solid functionality, reliability, and ease of use at its time.
