Maindec 701 PDP-7 Instruction Test

This document details MAINDEC 701, a comprehensive diagnostic program consisting of fourteen sub-programs (PR0 through PR13) designed to rigorously test the operational integrity of the PDP-7 computer's instructions.

The test suite covers a wide array of instructions, including all operate group instructions (with partial testing for OAS), memory reference instructions, indirect addressing, and auto-index registers. Instructions such as ADD, TAD, ISZ, XOR, SAD, and the rotate group are thoroughly checked using various number combinations, including random numbers, to ensure functionality across different data patterns and carry/skip conditions. Each sub-program verifies specific instruction behaviors like clearing registers, preserving link bits, correctly incrementing the Program Counter (PC), and handling conditional skips. Programs are often iterated multiple times, with checks on the AC Switch Register (ACSØ) dictating whether to repeat a test or advance to the next.

The document provides detailed instructions for loading the program (using a hardware read-in facility to avoid reliance on untested instructions) and configuring switch settings. It also includes an extensive error log, listing specific machine addresses (C(MA)), their causes, and recommended remedial actions to assist operators in diagnosing issues during test execution. Hardware requirements include a standard PDP-7, a high-speed reader, and/or a Teletype 33/35.