Motorola CPU32 Reference Manual page 314

Result Data:
Always returns 32 bits of data, regardless of the size of the register being
read. If the register is less than 32 bits, the result is returned zero extended.
Register Field:
The system control register is specified by the register field according to the
following table:
System Register Select Code
Return Program Counter (RPC)
0000
Current Instruction Program Counter (PCC)
0001
Status Register (SR)
1011
User Stack Pointer (USP)
1100
Supervisor Stack Pointer (SSP)
1101
Source Function Code Register (SFC) 1110
Destination Function Code Register (DFC) 1111
Temporary Register A (ATEMP)
1000
Fault Address Register (FAR)
1001
Vector Base Register (VBR)
1010
7.2.8.7 Write System Register (WSREG)
Operand data is written into the specified system control register. All registers
that can be written in supervisor mode can be written in BDM. Several internal
temporary registers are also accessible.
Command Format:
15
14 13 12 11
0
I
0
I
0
I
0
Command Sequence:
CPU32 REFERENCE MANUAL
10
9 8 7 6
I
1 0
I
0
I
0
I
DEVELOPMENT SUPPORT
5
0
I
4 3
0
0
I
REGISTER
NEXTCMD
"CMD COMPLETE"
MOTOROLA
7-21
II