Appendix B: POST Codes
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51
Keyboard detect and initialization.
10
Test DMA Controller 1
11
Test DMA Page registers
Test DMA Page Registers.
12-13
Reserved
14
Test Timer Counter 2
Test 8254 Timer 0 Counter 2.
15
Test 8259-1 Mask Bits
Verify 8259 Channel 1 masked interrupts by alternately turning off and on
the interrupt lines.
16
Test 8259-2 Mask Bits
Verify 8259 Channel 2 masked interrupts by alternately turning off and on
the interrupt lines.
17
Test Stuck 8259's
Interrupt Bits
Turn off interrupts then verify no interrupt mask register is on.
18
Test 8259 Interrupt
Functionality
Force an interrupt and verify the interrupt occurred.
19
Test Stuck NMI Bits
(Parity/IO Check)
Verify NMI can be cleared.
1A
Display CPU clock.
1B-1E
Reserved
1F
Set EISA Mode
If EISA non-volatile memory checksum is good, execute EISA initialization.
If not, execute ISA tests an clear EISA mode flag.
Test EISA Configuration Memory Integrity (checksum & communication
interface).
20
Enable Slot 0
Initialize slot 0 (System Board).
21-2F
Enable Slots 1-15
Initialize slot 1 through 15.
30
Size Base and Extended
Memory
Size base memory from 256 K to 640 K extended memory above 1 MB.
31
Test Base and Extended
Memory
Test base memory from 256 K to 640 K and extended memory above 1 MB
using various patterns.
F
This will be skipped in EISA mode and can be "skipped" with ESC key
in ISA mode.
32
Test EISA Extended
Memory
If EISA Mode flag is set then test EISA memory found in slots initialization.
F
This will be skipped in ISA mode and can be "skipped" with ESC key
in EISA mode.
33-3B
Reserved
3C
Setup Enabled
3D
Initialize & Install Mouse
Detect if mouse is present, initialize mouse, install interrupt vectors.
3E
Setup Cache Controller
Initialize cache controller.
3F
Reserved
BF
Chipset Initialization
Program chipset registers with Setup values.
40
Display virus protest disable or enable.
41
Initialize Floppy Drive &
Controller
Initialize floppy disk drive controller and any drives.
42
Initialize Hard Drive &
Controller
Initialize hard drive controller and any drives.
43
Detect & Initialize
Serial/Parallel Ports
Initialize any serial and parallel ports (also game port).
44
Reserved
45
Detect & Initialize Math
Coprocessor
Initialize math coprocessor.
46
Reserved
47
Reserved
48-4D
Reserved
4E
Manufacturing POST
Loop or Display
Messages
Reboot if Manufacturing POST Loop pin is set. Otherwise display any
messages (i.e., any non-fatal errors that were detected during POST) and
enter Setup.
4F
Security Check
Ask password security (optional).
50
Write CMOS
Write all CMOS values back to RAM and clear screen.
