Memory circuit with feedback shift register and comparator - has defined addresses for test data supplied by built-in test circuit for functional check on memory

摘要

The memory (1), having data and address input (2, 4) from separate switches (3, 5), delivers outputs from a predetermined sequence of addresses to the shift register (18), whose content is compared (19) with a desired value in a complete readout cycle. The test circuit (9) consists of a microprocessor (13) and a test memory (14) coupled (8) to the data input switch (3). It selects (15) either write or read mode for the memory (1), operates (11) the address input switch (5), and sets (20) the shift register (18) initially. ADVANTAGE - A check on correct operation of the memory is easily applied without recourse to very complex circuitry.