TABLE II Clock RAM Bit Map for Alarm Interrupt Everyday at 1015 am

Address

Data

Function

Hi Nibble

Lo Nibble

4321076

5

4

32

1

0

Milliseconds

0

1

0

0

0

0

0

0

0

No RAM Exists

Hundredths and

0100100

0

0

00

0

0

Tenths of Seconds

Seconds

0

1

0

1

0

0

0

0

0

0

0

0

0

Minutes

0

1

0

1

1

0

0

0

1

0

1

0

1

Hours

0

1

1

0

0

0

0

0

1

0

0

0

0

Day of Week

0

1

1

0

1

No RAM Exists

1

1

X

X

Day of Month

0

1

1

1

0

1

1

X

X

1

1

X

X

Months

0

1

1

1

1

1

1

X

X

1

1

X

X

TABLE III Address Codes and Function

A4

A3

A2

A1

A0

Function

0

0

0

0

0

CounterMilliseconds

0

0

0

0

1

CounterHundredths and Tenths of Seconds

0

0

0

1

0

CounterSeconds

0

0

0

1

1

CounterMinutes

0

0

1

0

0

CounterHours

0

0

1

0

1

CounterDay of Week

0

0

1

1

0

CounterDay of Month

0

0

1

1

1

CounterMonth

0

1

0

0

0

RAMMilliseconds

0

1

0

0

1

RAMHundredths and Tenths of Seconds

0

1

0

1

0

RAMSeconds

0

1

0

1

1

RAMMinutes

0

1

1

0

0

RAMHours

0

1

1

0

1

RAMDay of Week

0

1

1

1

0

RAMDay of Month

0

1

1

1

1

RAMMonths

1

0

0

0

0

Interrupt Status Register

1

0

0

0

1

Interrupt Control Register

1

0

0

1

0

Counters Reset

1

0

0

1

1

RAM Reset

1

0

1

0

0

Status Bit

1

0

1

0

1

GO Comand

1

0

1

1

0

STANDBY INTERRUPT

1

1

1

1

1

Test Mode

All others unused

The comparator is a cascaded exclusive NOR Its output is

latched 61 ms after the rising edge of the 1 kHz clock signal

(input to the milliseconds counter) This allows the counter

to ripple through before looking at the comparator For oper-

ation at less than 45V the thousandths of seconds counter

should not be included in a compare because of the possi-

bility of having a ripple delay greater than 61 ms (For output

timing see Interrupt Timing)

Power Down Mode

The POWER DOWN input is essentially a second chip se-

lect

It disables all inputs and outputs except for the

STANDBY INTERRUPT When this input is at a logical zero

the device will not respond to any external signals It will

however maintain timekeeping and turn on the STANDBY

INTERRUPT if programmed to do so (The programming

must be done before the POWER DOWN input goes to a

4