
General Control and Status Registers
8-13
`efmp69030 Databook
Revision 1.3 11/24/99
MSS
Memory Space Shadowing Register
read/write at I/O address 3CBh
shared by both pipelines A and B
7-4
Reserved
These bits always return the value of 0 when read.
3
Memory Space Shadowing Enable
0: Disables memory space shadowing. All registers for pipeline A remain mapped to mem-
ory offsets 400000 through 7FFFFF. All registers for pipeline B remain mapped to memory
offsets C00000 through FFFFFF. This is the default after reset.
1: Enables memory space shadowing. All shadows of all registers for either pipeline A or
B (not both at the same time) are accessible at both memory offsets 400000 through
7FFFFF and C00000 through FFFFFF. The choice of which pipeline’s registers are to be
made accessible for reading or writing is controlled via bits 2 through 0 of this register.
2
Pipeline A or B Register Read Select
Note: This bit has no effect if bit 3 of this register is set to 0.
0: If bit 3 of this register is set to 1, then the registers belonging to or shared by pipeline A
are accessible for reading via both memory offsets 400000 through 7FFFFF and C00000
through FFFFFF, and those registers belonging exclusively to pipeline B are not. This is
the default after reset.
1: If bit 3 of this register is set to 1, then the registers belonging to or shared by pipeline B
are accessible for reading via both memory offsets 400000 through 7FFFFF and C00000
through FFFFFF, and those registers belonging exclusively to pipeline A are not.
1
Pipeline A Register Write Enable
Note: This bit has no effect if bit 3 of this register is set to 0.
0: If bit 3 of this register is set to 1, then the registers belonging exclusively to pipeline A
are NOT accessible for writing via either memory offsets 400000 through 7FFFFF or
C00000 through FFFFFF. This is the default after reset.
1: If bit 3 of this register is set to 1, then the registers belonging to or shared by pipeline A
are accessible for writing via memory offsets 400000 through 7FFFFF.
0
Pipeline B Register Write Enable
Note: This bit has no effect if bit 3 of this register is set to 0.
0: If bit 3 of this register is set to 1, then the registers belonging exclusively to pipeline B
are NOT accessible for writing via either memory offsets 400000 through 7FFFFF or
C00000 through FFFFFF. This is the default after reset.
1: If bit 3 of this register is set to 1, then the registers belonging to or shared by pipeline B
are accessible for writing via memory offsets C00000 through FFFFFF.
76
54
32
10
A
&
B
Reserved
(0000)
Mem Shad
En
(0)
A/B Reg
Read
(0)
Pipe A Reg
Write
(0)
Pipe B Reg
Write
(0)