32-Bit Prescaler Count Register - Motorola MVME162FX Programmer's Reference Manual

MC2 Chip

32-bit Prescaler Count Register

3
ADR/SIZ
BIT
NAME
OPER
RESET
3-50
The prescaler register is used to clock timing functions in the MC2
chip. The lower 8 bits of the prescaler is programmed to generate an
output with a one microsecond period. Refer to LSB Prescaler Count
Register on page 3-18. The upper 24 bits are used to clock the local
bus access timer and watchdog timer. To facilitate testing, the
upper 24 bits can be written to. Writes to this register must be 32
bits.
The least significant bits of the 32-bit prescaler.
LSB7-0
These bits are read only. They are duplicated in the
memory map in the MC2 chip at $FFF42014.
The most significant bits of the prescaler.
MSB31-8
Note that for the ÒNo VMEbus InterfaceÓ option, the
32-bit Prescaler Count Register is located at
$FFF40064 in addition to $FFF4204C. This means
that this register is located at the same address
($FFF40064) on an MVME162FX with the VMEchip2
as well as an MVME162FX without the VMEchip2.
This feature is provided for those applications
which require a Prescaler Count Register to run on
all MVME162FX versions.
$FFF4204C (32 bits)
31 . . . 8
MSB
R/W
0 P
7-0
LSB
R