Casio AL-1000 Calculator
Technical Description

This article presents a detailed technical description of the Casio AL-1000 calculator. The contents of this article are based on a reverse engineering of one unit of this calculator, which I received in a dismantled and non-functional state (it was missing the case and power supply and the bundle of 50-or-so wires connecting the keyboard to the backplane had been chopped).

This article is an adjunct to the schematic produced from the reverse engineering. Some references and descriptions may not make much sense without reference to the schematic. A simulation of the AL-1000 has also been completed and can be used to observe the execution of the procedures described in this article.

The AL-1000 dates from the late 1960s. It provides the basic four arithmetic functions and square root. Simple straight-line programs of up to 30 steps can be stored and executed by the AL-1000. It utilises more than 400 discrete transistors, over 1500 diodes, Nixie tubes for the display, and core memory for number and program storage.

The AL-1000 was also sold under the Commodore label.


  1. Architecture
    1. Elements and Structure
    2. Memory Organisation
    3. Printed Circuit Board Contents

  2. Electronic Implementation of Logic
    1. Supply Voltages and Logic Levels
    2. Gates
    3. Bistable Flip-Flops
    4. Monostable Flip-Flops
    5. Edge-Pulse Gates

  3. The Arithmetic Unit

  4. Basic Timing
    1. The Digit Clock and the Number Cycle
    2. The Display Cycle
    3. The State Clock and State Transitions
  1. The T State Machine

  2. Function Execution State Descriptions
    1. State Actions
    2. Shift State Cycles
    3. Arithmetic State Cycles
    4. Register Copy State Cycles
    5. Decimal-Point-Only State Cycles

  3. Function Execution State Machine Procedures
    1. The Main Loop
    2. Clearing
    3. Addition, Subtraction, Memory Accumulation
    4. Memory Retrieval & Saving
    5. Rounding
    6. Multiplication (and example)
    7. Division (and example)
    8. Square Root (and example)

  4. Numeral Entry

Other information about the AL-1000:

  Architecture | Electronics | Arithmetic | Timing | T States | States | Procedures | Numeral-Entry
Casio AL-1000 Technical Description
Nov 2004