3

MC2 Chip

Tick Timer 4 Compare Register

ADR/SIZ

 

$FFF42038 (32 bits)

 

 

 

 

 

BIT

31

. . .

0

 

 

 

 

NAME

 

Tick Timer 4 Compare Register

 

 

 

 

 

OPER

 

R/W

 

 

 

 

 

RESET

 

0 P

 

 

 

 

 

Tick Timer 4 Counter

ADR/SIZ

 

$FFF4203C (32 bits)

 

 

 

 

 

BIT

31

. . .

 

0

 

 

 

 

 

NAME

 

Tick Timer 4

Counter

 

 

 

 

 

OPER

 

R/W

 

 

 

 

 

 

 

RESET

 

X

 

 

 

 

 

 

 

Bus Clock Register

The Bus Clock Register should be programmed with the hexadecimal value of the operating clock frequency in MHz (i.e., $21 for 33 MHz). The MC2 chip uses the value programmed in this register to control the refresh timer so that the DRAMs are refreshed every 15.6 microseconds. After power-up, this register is initialized to $10 (for 16 MHz).

ADR/SIZ

 

 

 

$FFF42040 (8 bits)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BIT

31

30

29

 

28

27

 

26

25

24

 

 

 

 

 

 

 

 

 

 

 

NAME

 

 

BCK5

 

BCK4

BCK3

 

BCK2

BCK1

BCK0

 

 

 

 

 

 

 

 

 

 

OPER

R/W

R/W

 

 

 

R/W

 

 

 

 

 

 

 

 

 

 

 

 

 

RESET

0 P

0 P

0 P

 

1 P

0 P

 

0 P

0 P

0 P

 

 

 

 

 

 

 

 

 

 

 

3-38

Computer Group Literature Center Web Site

Page 226
Image 226
Motorola MVME172 manual Bus Clock Register, Tick Timer 4 Compare Register, Tick Timer 4 Counter