Digital Circuit Analyzer: Logic Board Tester Makes a Powerful Diagnostic Tool in Design, Production, and Maintenance

摘要

A portable digital circuit analyzer features 120 independently-programable input/output (I/O) channels for testing large, complex integrated-circuit (IC) boards. It has 15-MHz speed (data change rate) and 1024-bit storage capacity per channel. The instrument also doubles as a basic 120-channel time-domain analyzer, providing triggering on any data pattern with up to 4095 steps of post-trigger recording within the storage capacity of 1024 memory locations. As a board tester, the instrument detects and displays logic errors, including slow-logic and timing problems. The boards are tested by comparing their signature with that of a good logic board used as a reference. Errors in the board under test are revealed by the alternate flashing of both the good signature and the test signature on the same set of display lights. Each channel of the analyzer may be independently or jointly edited, and during logic testing, it may independently assume any of its three primary functions: (1) transmitter (OUTPUT), (2) receiver (INPUT), and (3) recorder (by default when neither OUTPUT nor INPUT). Programing is uncomplicated, and programs may be modified during board testing - a necessary feature in troubleshooting unfamiliar boards. Such modifications include the addition or deletion of entire I/O channels, and data-string generation of any predetermined length of 1's, 0's, or random patterns. This is in addition to single-bit changes. It is possible to load automatically square waves of varying periods, ranging from a change at every memory location to a change after each 64 memory locations, each period being twice as long as the preceding one. (ERA citation 09:006384)