| 摘要 |
PURPOSE: A device for protecting stored data while testing internal ROM is provided to dump ROM data by identification of expected value and compressing result after compressing separate code data with an MISR(multiple input signature analysis register) method. CONSTITUTION: A control state machine(12) outputs a control signal(MisrEn) of ROM test operation by test enable/clock signals(TstEn,CLK). Herein, the signals are enabled while testing internal ROM(10). An MISR circuit unit(14) receives a code data(LD) for outputting a compressing result by clock/control signals. A comparer(20) compares the compressing result with an expected value(MisrEn) for outputting a reading enable signal(ROMReadEn). A switch element(16) initializes the MISR circuit unit by test enable/reset signals. An AND gate(18) dumps ROM data after operating logical AND the ROM data of ROM(10) and the reading enable signal.
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