1 short

DRAM refresh

2 short

Parity circuit

3 short

Base 64K RAM

4 short

System timer

5 short

Processor

6 short

Keyboard controller gate
A20

7 short

Virtual mode exception

8 short

Display memory read/write test

9 short

ROM BIOS checksum

10 short

CMOS shutdown read/write

11 short

Cache memory

Conventional/extended memory

1 long, 8 short

Display/retrace test

None

CPU register test

None

First 64K RAM test

None

Interrupt vector loading proceeding

None

CMOS power failure/checksum calculation

None

Display configuration validation proceeding

None

Display running with video ROM

None

Display functional

None

Mononchrome display functional

None

CGA display functional

1-1-3

CMOS write/read

1-1-4

ROM BIOS checksum

1-2-1

Programmable interval timer

1-2-2

DMA Initialization

1-2-3

DMA page register write/read

1-3-1

RAM refresh verification

1-3-3

st 64K RAM chip or data line

1-3-4

First 64K RAM odd/even logic

1-4-1

Address line first 64K RAM

1-4-2

Parity failure first 64K RAM

2-1-1

Bit 0, first 64K RAM

2-1-2

Bit 1, first 64K RAM

2-1-3

Bit 2, first 64K RAM

2-1-4

Bit 3, first 64K RAM

2-2-1

Bit 4, first 64K RAM

2-2-2

Bit 5, first 64K RAM

2-2-3

Bit 6, first 64K RAM

2-2-4

Bit 7, first 64K RAM

2-3-1

Bit 8, first 64K RAM

2-3-2

Bit 9, first 64K RAM

2-3-3

Bit 10, first 64K RAM

2-3-4

Bit 11, first 64K RAM

2-4-1

Bit 12, first 64K RAM

2-4-2

Bit 13, first 64K RAM

2-4-3

Bit 14, first 64K RAM

2-4-4

Bit 15, first 64K RAM

3-1-1

Slave DMA register

3-1-2

Master DMA register

3-1-3

Master interrupt mask register

3-1-4

Slave interrupt mask register

3-2-4

Keyboard controller

3-3-4

Display initialization

3-4-1

Display retrace

3-4-2

Search for video ROM proceeding

4-2-1

Timer tick interrupt test

4-2-2

Shutdown test

4-2-3

Gate A20 Failure

4-2-4

Unexpected interrupt in protected mode

4-3-1

RAM test

4-3-3

Interval timer channel 2

4-3-4

Real time clock

4-4-1

Serial Port

4-4-2

Parallel Port

4-4-3

Math Co-processor test

1-1-2*

System board select

1-1-3*

Extender CMOS RAM

*audio code pattern preceded by low pitched tone

none

System board, power supply

1 short

System passed all tests

2 short

Display error

continuous

System board, power supply

1 long, 1 short

System board

1 long, 2 short

Video adapter

1 long, 3 short

EGA

3 long

3270 keyboard card