3

PCCchip2

Tick Timer 2 Control Register

This is an 8-bit read/write register that controls Tick Timer 2. It is located at address $FFF42016.

ADR/SIZ

 

 

$FFF42016 (8 bits)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BIT

15

14

13

12

11

 

10

9

 

8

 

 

 

 

 

 

 

 

 

 

 

NAME

OVF3

OVF2

OVF1

OVF0

 

 

COVF

COC

 

CEN

 

 

 

 

 

 

 

 

 

 

 

OPER

R

R

R

R

R

 

C

R/W

 

R/W

 

 

 

 

 

 

 

 

 

 

 

RESET

0 PL

0 PL

0 PL

0 PL

0

 

0 PL

0 PL

 

0 PL

 

 

 

 

 

 

 

 

 

 

 

CEN

Counter Enable. When this bit is high, the counter

 

 

 

increments. When this bit is low, the counter does not

 

 

increment.

 

 

 

 

 

 

 

 

COC

Clear On Compare. When this bit is high, the counter is

 

 

reset to zero when it compares with the compare register.

 

 

When this bit is low, the counter is not reset.

 

 

COVF

Clear Overflow Counter. The overflow counter is cleared

 

 

when a one is written to this bit.

 

 

 

OVF3-OVF0These four bits are the outputs of the overflow counter. The overflow counter is incremented each time the tick timer sends an interrupt to the Local Bus interrupter. The overflow counter can be cleared by writing a one to the COVF control bit.

3-22

Computer Group Literature Center Web Site

Page 220
Image 220
Motorola MVME1X7P manual Cen, Clear On Compare. When this bit is high, the counter is