General Control Register - Motorola MVME1X7P Programmer's Reference Manual

General Control Register

The General Control Register is located at $FFF42002. It is an 8-bit
register that controls chip general functions. The Master Interrupt Enable
bit (MIEN) must be set high for any interrupts from the PCCchip2 to be
asserted to the processor.
ADR/SIZ
DIR 15
NAME
DR0
OPER R/W
RESET
V PL
FAST
Note
MIEN
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$FFF42002 (8 bits)
14 13 12
R R
0 0
This control bit tailors the control circuit for BBRAM to
the speed of BBRAM.
The PCCchip2 runs at half the MPU speed on the MVME177P.
For example, an MVME177P with a 50 MHz MPU will run the
PCCchip2 at 25 MHz.
When operating at 25 MHz, the FAST bit should be
cleared for devices with access times longer than 200 ns
(5 CLK cycles). The bit can be set for devices that have
access times of 200 ns or faster. It is not allowed to use
devices slower than 360 ns (9 CLK cycles), at 25 MHz.
When operating at 33 MHz, the FAST bit should be
cleared for devices with access times longer than 150 ns
(5 CLK cycles). The bit can be set for devices that have
access times 150 ns or faster. It is not allowed to use
devices slower than 270 ns (9 CLK cycles), at 33 MHz.
Master Interrupt Enable. When this bit is high, interrupts
from and via the PCCchip2 are allowed to reach the MPU.
When it is low, all interrupts from the PCCchip2 are
disabled (this includes both the EIPL* pins and the INT
pin). Also, when the bit is low, all interrupt acknowledge
cycles to the PCCchip2 are passed on, via the IACKOUT*
pin. This bit is cleared by a reset.
11 10
C040
R R R/W
0 0 0 P
Programming Model
9 8
MIEN FAST
R/W R/W
0 PL 0 P
3-15
3