BIOS POST Codes - Page 3 of 6
Code | LED Display | Description |
40h | ![]() |
Preparing the virtual mode test. Verify from display memory next. |
41h | ![]() |
Returned to POST after verifying from display memory. Preparing the descriptor tables next. |
42h | ![]() |
The descriptor tables have been prepared. Entering virtual mode for the memory test next. |
43h | ![]() |
Entered virtual mode. Enabling interrupts for diagnostics mode next. |
44h | ![]() |
Interrupts are enabled if the diagnostics switch is on. Initializing data to check the memory wraparound at 0:0h next. |
45h | ![]() |
Data has been initialized for the memory wraparound check. Checking for memory wraparound at 0:0h and finding the total system memory size next. |
46h | ![]() |
The memory wraparound test has been done. The memory size calculation has been done. About to write memory test patterns. |
47h | ![]() |
The memory test patterns were written to extended memory. Writing patterns in conventional memory (first 640 KB) next. |
48h | ![]() |
The patterns to be tested were written to conventional memory. Finding the amount of memory below 1 MB next. |
49h | ![]() |
The amount of memory below 1 MB was found and verified. Finding the amount of memory above 1 MB next. |
4Ah | ![]() |
The amount of memory above 1 MB was found and verified. Performing the BIOS ROM data area check test next. |
4Bh | ![]() |
The BIOS ROM data area check is done. Checking the Del key status and clearing the memory below 1 MB for a soft reset next. |
4Ch | ![]() |
The memory below 1 MB has been cleared via a soft reset. Clearing the memory above 1 MB next. |
4Dh | ![]() |
The memory above 1 MB has been cleared via a soft reset. Clearing the memory size next. |
4Eh | ![]() |
The memory test has started. No soft reset was performed. About to display the first 64 KB memory test. |
4Fh | ![]() |
The memory size display has started. This display is updated during the memory test. Running the sequential and random memory test. |
50h | ![]() |
The test of memory below 1 MB completed. Adjusting the memory size for relocation and shadowing next. |
51h | ![]() |
The memory size has been adjusted for memory relocation above 1 MB and shadowing options. The test of memory above 1 MB is next. |
52h | ![]() |
The test of memory above 1 MB has completed. Preparing for real mode next. |
53h | ![]() |
The CPU registers have been saved, including the memory size. Entering real mode next. |
54h | ![]() |
Shutdown was successful and the CPU is in real mode. Restoring the registers saved during preparation for shutdown next. |
55h | ![]() |
The registers have been restored. Disabling the Gate A20 address line next. |
56h | ![]() |
The Gate A20 address line was disabled successfully. Checking the BIOS ROM data area next. |
57h | ![]() |
The BIOS ROM data area check is partially completed. Completing the BIOS ROM data area check next. |
58h | ![]() |
The BIOS ROM data area check has completed. Clearing the OHit DelO message next. |
59h | ![]() |
The "Hit Del" message has been cleared. About to start the DMA and interrupt controller tests. |
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