| 摘要 |
PURPOSE:To execute the prediagnosis of start of a ROM, a PLA, etc., in an LSI by directly controlling the ROM, PLA, etc., from the outside of the LSI to execute the diagnosis of the ROM, PLA, etc., fetched in the LSI. CONSTITUTION:At the time of leading a system, a ROM diagnosis starting signal is sent from an external logic to a sequencer 12 through an input terminal 2. The sequencer 12 increases the value of an address counter 11 successively from all zeros. When the value of the counter reaches its maximum, the sequencer 16 sends an increment completion signal to a comparator 16. The contents of the counter 11 are sent to the ROM 13 as an address and the data of the ROM 13 are sent to a computing element 14 to execute exclusive OR operation. The initial state of the register 15 is all zeros, and at every reading of data from the ROM 13, exclusive OR operation between the value of the register 15 and the value of the data read out from the ROM 13 is executed by the computing element 14 and the computed result is compared with the output of the sequencer 12 by the comparator 16. |
