PDP-7 Tape Reader (Type 444B) Test

Maindec 710 is a diagnostic program designed to test the functionality and accuracy of the PDP-7 Tape Reader (Type 444B). It comprises two distinct test sections.

Section 1: Maximum Noise Test This section evaluates all IOT (Input/Output Transfer) instructions associated with the tape reader, the performance of the program interrupt, and the accuracy of information transfer, particularly under conditions of maximum noise. It achieves this by reading a continuous loop of paper tape containing alternating 1's and 0's, first in alphanumeric mode and then in binary mode. An auxiliary program is used to punch this specific test tape.

Section 2: Numeric Sequence Test This test focuses on verifying the reading accuracy of the tape reader for every possible combination of bits. It reads a loop of tape containing the numeric sequence 1-377, repeated three times. Unlike Section 1, this test does not utilize the program interrupt and assumes that the system's flags are functioning correctly.

General Features & Operation:

• Both sections require the RIM Loader and utilize library subroutines like the Teletype Output Package and Octal Print Subroutine.
• The reading speed of the tape reader can be controlled and adjusted via the AC switches (ranging from 3 to 300 characters per second), allowing operators to identify speed-dependent failures.
• The program provides detailed error messages (E01-E33) that include the error code, cause, and recovery procedures for issues such as I/O flag failures, data mismatches between read and expected characters, incorrect leader signals, or interrupt problems.
• The test requires a standard PDP-7 system equipped with a paper tape reader and punch, and it is restricted to operation with the Automatic Priority Interrupt (API) disabled.