
General Control and Status Registers
8-9
`efmp69030 Databook
Revision 1.3 11/24/99
2
I/O Space Register Read Select
This bit defaults to the value of 0 after reset.
For the FCR, MSR, MSS, ST00 and ST01 registers:
0: All of these direct-access registers that either belong to or are shared by pipeline
A are made readable from the I/O space. None of these direct-access registers
that belong exclusively to pipeline B are readable from the I/O space.
1: All of these direct-access registers that either belong to or are shared by pipeline
B are made readable from the I/O space. None of these direct-access registers
that belong exclusively to pipeline A are readable from the I/O space.
For the CR sub-indexed register group:
0: The CR sub-indexed register group that belongs to pipeline A is made readable
from the I/O space using pipeline A’s index for this register group. Neither the CR
sub-indexed register group that belongs to pipeline B, or its index, are readable
from the I/O space.
1: The CR sub-indexed register group that belongs to pipeline B is made readable
from the I/O space using pipeline B’s index for this register group. Neither the CR
sub-indexed register group that belongs to pipeline A, or its index, are readable
from the I/O space.
Note: Write access to the index for the CR sub-indexed register group must be
enabled using bits 1 and 0 of this register, since this index is controlled in the same
way as the CR sub-indexed registers.
For the FR, GR, MR, SR and XR sub-indexed register groups:
0: All of these sub-indexed register groups that either belong to or are shared by
pipeline A are made readable from the I/O space. None of these sub-indexed reg-
ister groups that belong exclusively to pipeline B are readable from the I/O space.
1: All of these sub-indexed register groups that either belong to or are shared by
pipeline B are made readable from the I/O space. None of these sub-indexed reg-
ister groups that belong exclusively to pipeline A are readable from the I/O space.
Note: Which pipeline’s indices for these sub-indexed register groups are used in
accessing the actual sub-indexed registers, and whether or not the selected indi-
ces are writable are controlled by bits 3 and 4, respectively, of this register.
For the AR and DAC register groups:
0: The AR and DAC sub-indexed register groups that belong to pipeline A are
made readable from the I/O space using pipeline A’s indices for these register
groups. Neither of these sub-indexed register groups that belong to pipeline B, or
their indices, are readable from the I/O space.
1: The AR and DAC sub-indexed register groups that belong to pipeline B are
made readable from the I/O space using pipeline B’s indices for these register
groups. Neither of these sub-indexed register groups that belong to pipeline A, or
their indices, are readable from the I/O space.
Note: Write access to the indices for the AR and DAC sub-indexed register groups
must be enabled using bits 1 and 0 of this register, since these indices are con-
trolled in the same way as the actual sub-indexed registers of these groups.