IBM AT 5170 Technical Reference page 76

Bit 6 Configuration Record (Checksum Status
Bit
S
Bit 4
Bit 3
Bit 2
Bit 1-Bit 0
Indicator)-A 0 indicates that checksum is good,
and a 1 indicates it is bad.
Incorrect Configuration Information-This is a
check, at power-on time, of the equipment byte
of the configuration record. A 0 indicates that
the configuration information is valid, and a 1
indicates it is invalid. Power-on checks require:
• At least one diskette drive to be installed (bit
o
of the equipment byte set to
1).
• The primary display adapter setting in
configuration matches the system board's
display switch setting and the actual display
adapter hardware in the system.
Memory Size Comparison-A 0 indicates that
the power-on check determined the same memory
size as in the configuration record, and a 1
indicates the memory size is different.
Fixed Disk Adapter/Drive C Initialization
Status-A 0 indicates that the adapter and drive
are functioning properly and the system can
attempt "boot up." A
1
indicates that the
adapter and/or drive C failed initialization, which
prevents the system from attempting to "boot
up."
Time Status Indicator (POST validity check)- A
o
indicates that the time is valid, and a 1 indicates
that it is invalid.
Reserved
1-60
System
Board