The Commodore F4146R is a financial calculator from 1976, produced by Commodore Business Machines in Palo Alto, California. Made for serious users, it features a unique black, two-piece plastic case with a red LED display. Its keys, in various colors, include financial and mathematical functions, all organized by a silver line that separates financial functions for ease of use. This model’s characteristic red LED display includes a bubble lens, which magnifies and enhances readability. Powering this calculator is a 6V DC rechargeable battery pack with support for adapters, making it portable but potentially power-intensive.
Specifications
- Dimensions: 80mm x 150mm x 20-35mm (width, height, depth)
- Weight: Approximately 160g, excluding batteries
- Power Supply: 6V DC from 4 x AA internal rechargeable batteries or compatible adapters (DC640, 708, or 709)
- Display: Red LED with bubble and linear lenses, displaying 10 main digits, plus 2 smaller digits for exponents
- Case Design: Stippled black plastic with squishy yet responsive keys
- Notable Features: Four basic functions, memory capabilities, summation mode, financial and percentage calculations, and change sign functionality
Components
- CPU: Commodore GHU-03A 7605 (dated 1976)
- Additional Components: Display driver ICs (ITT 546A-5N), a 14-digit LED, a transistor, diode, capacitors, and resistors
- Board Layout: Keyboard board sits below the main CPU board, with ribbon cables connecting to the display board
Logic
- CE: Cancels the last entered number
- C: Clears the entire calculator
- Constant Functions: Automatically applies to multiplication and division
- Overflow Control: Limits input to 12 digits, suppresses excess, and shows errors for zero division
- Negative Indicator: Displays a minus sign in the left-most digit for full eight-digit negative numbers
- Memory: Lacks visual indicators, requiring users to recall stored values
- Function Keys:
- CMP: Appears to be used for computations, such as exponentiation
- X<->Y: Swaps registers
- INT: Has an undefined function, not necessarily integer or intercept
- Financial Keys: Include present value (PV), future value (FV), payment (PMT), interest rate (I), and time periods (N)
The Commodore F4146R’s robust design, financial functionality, and magnifying display made it a distinctive choice for financial calculations, though it lacked some more advanced features, such as square root calculations and error recovery mechanisms.
