IBM 770 CMOS RAM Configuration, Bits, Byte Hex 00E, System Board, 20. Diagnostic, Status Byte

Bit	7	This	read-only bit monitors the			internal		battery.		If	set to
		1, this bit		indicates that	the		real-time		clock	has	power. If
		set to 0, it indicates that the					real-time		clock	has	lost
		power	and the data in CMOS		is	no	longer	valid.
Bits	6–0	These	bits	are reserved.

CMOS RAM Configuration

Figure 2-20 shows the bit definitions for the CMOS RAM configuration bytes.

Diagnostic Status	Byte (Hex 00E)
Bit	Function
7	Real-time clock power
6	Configuration record and checksum status

5Incorrect configuration

4Memory size mismatch

3	Hard	disk	controller/drive C initialization status
2	Time	status	indicator
1, 0	Reserved

Figure 2-20. Diagnostic

Status Byte

(Hex 00E)

Bit

7

If

set

to

1,

this

bit

indicates

that

the

real-time

clock

has

lost

power.

Bit

6

If

set

to

1,

this

bit

indicates

that

the

checksum

is incorrect.

Bit

5

This

bit indicates the results of a power-on check of the

equipment

byte (hex 014). If set to 1, this bit indicates

that

the

configuration

information is

incorrect.

Bit

4

If

set

to 1, this bit indicates that the memory size does not

match

the

configuration

information.

Bit

3

If

set

to

1,

this

bit

indicates

that

the

controller

or

hard disk

drive

failed initialization.

Bit

2

If

set

to

1,

this

bit

indicates

that

the

time is

invalid.

Bits

1,

These0

bits

are

reserved.

Shutdown Status Byte (Hex 00F): This byte is defined by the power-on diagnostic programs.

System Board 2-25