Toshiba Tecra A2-S239 Maintenance Manual - Page 123

3.6 Memory Test 3 Tests and Diagnostics 3.6 Memory Test To execute the Memory Test, select 2 from the DIAGNOSTIC TEST MENU, press Enter and follow the directions on the screen. Move the highlight bar to the subtest you want to execute and press Enter. Subtest 01 Conventional Memory This subtest writes a 256-byte unit of constant data to conventional memory (0 to 640 KB). Then reads the new data and compares the result with the original data. The content of the memory to be tested is saved before the test and it is restored after the test. The constant data is FFFFh, AAAAh, 5555h, 0101h and 0000h. Subtest 02 Protected Mode NOTE: The CONFIG.SYS file must be configured without extended memory manager programs such as EMM386.EXE, EMM386.SYS or QEMM386.SYS. Also, the HIMEM.SYS must be deleted from the CONFIG.SYS file. This subtest writes constant data (FFh, AAh, 55h, 00h) and address data (FFFFh, FFFEh, ... 0000h) to from 1MB to the maximum MB then reads the new data and compares the result with the original data and executes the address bit test (in 64KB unit. FFh, FEh, ...). Subtest 04 Cache Memory To test the cache memory, a pass-through write-read comparison of '5A' data is run repeatedly to the test area ('7000':'Program' size to '7000':'7FFF' (32KB)) to check the hit-miss ratio (on/off status) for CPU cache memory. Number of misses < Number of hits → OK Number of misses ≥ Number of hits → Fail Satellite A50/TECRA A2 Maintenance Manual (960-478) 3-15