IBM 560E manual Status Register C Hex, Status Register D Hex 00D

Bit 0	When	set	to	1, this		bit enables the daylight-saving-time
	mode. When set to 0, this bit disables the
	daylight-saving-time mode, and the clock reverts to
	standard time. The				system initializes this bit to 0.
Status	Register C	(Hex	00C)
	Bit	Function
	7	Interrupt		request		flag
	6	Periodic		interrupt		flag
	5	Alarm	interrupt		flag
	4	Update-ended interrupt flag
	3–0	Reserved

Figure

2-18. Status Register C (Hex 00C)

Note:

Interrupts are

enabled

by bits

6, 5,

and 4

in

status

register B.

Bit

7

When set to 1, this bit indicates that an interrupt has

occurred;

bits

6, 5,

and

4

indicate the

type of

interrupt.

Bit

6

When

set

to

1,

this

bit

indicates

that

a

periodic

interrupt

has

occurred.

Bit

5

When

set

to

1,

this

bit

indicates

that

an

alarm

interrupt

has

occurred.

Bit

4

When set to 1, this bit indicates that an update-ended

interrupt

has

occurred.

Bits 3–0These bits are reserved.

Status Register D (Hex 00D)

BitFunction

7Valid RAM

6–0Reserved

Figure

2-19. Status Register

D

(Hex 00D)

Bit

7

This read-only bit

monitors

the

internal

battery. When

set to

1,

this

bit

indicates

that

the real-time clock has

power. When

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.

ThinkPad 560/560E System Board 2-21