Abstract: Test node equipment is provided between successive component groups operating in cascade and each test node is connected to a data bus system through which test patterns can be provided by a test pattern generator and from which signals can be evaluated by a test pattern analyzer, the test pattern generator and the test pattern analyzer being under control of a test computer. Each test node has a state in which the output of the preceding component group passes through it to the next component group with only a possibility of monitoring possible deficiencies by the test computer and other states in which the cascade operation of component groups can be interrupted at a test node for inserting a test pattern to a following component group or receiving a processed test pattern from a preceding component group.

Abstract: A system for testing and/or monitoring a digital videotape apparatus makes use of the presence several identically equipped recording and reproducing channels to detect or test for errors by comparing the treatment of the same data in two or more channels. Comparisons are made at test nodes between reference "signatures" and actual "signatures" in normal operation or in test operation. Syndrome units are used to test or monitor circuits for protection against errors and for error correction. The monitoring and testing is done in a system which connects a microcomputer to test nodes of the equipment to be tested or monitored over a test bus.