Logsim-8

Summary LOGSIM-8 is an interactive digital logic simulation program designed for the PDP-8 computer. It allows users to simulate combinational and sequential logic circuits at the gate level.

Key features include:

• Simulation Language: The system uses two types of statements: logic statements (which define gates like AND, OR, NOT, NAND, NOR, and XOR) and control statements (INPUT, OUTPUT, CYCLE, and SET) for managing variables and program execution.
• Logic Representation: Circuits are described using variable names and functional elements (including flip-flops like JK, D, SR, and CSR).
• Operation: LOGSIM-8 operates similarly to FOCAL, utilizing a command mode and a buffer for storing simulation statements. It provides basic editing commands (Insert, Append, Delete, List) to manage circuit descriptions.
• Execution: The simulation is run via the "G" command. It handles variables as having three states: 0, 1, or undefined. The program also features error detection and handles sequential logic by allowing memory elements to update at the end of a simulation pass.
• Limitations: Internal memory allows for 128 variables, 128 simulation statements, and 4000 characters of buffer storage.