Internal I/O Memory Map - Motorola DSP56009 User Manual

purpose routine in which the switch conditions are always met, independent of
where the program flow originates (before the switch) or where it proceeds (after the
switch) is shown below:
;Switch to Program RAM enabled:
ORI #03,MR
INST1
INST2
INST3
INST4
ORI #$C,OMR
ANDI #$FC,MR
JMP >Next_Address
;Switch to Program RAM disabled:
ORI #03,MR
INST1
INST2
INST3
INST4
ANDI #$F3,OMR
ANDI #$FC,MR
JMP >Next_Address
Note: "Next_Address" is any valid program address in the new memory
configuration (after the switch). The 2-word instruction "JMP
>Next_Address" can be replaced by a sequence of an NOP followed by a
1-word "JMP <Next_Address" (jump short) instruction. In cases in which
interrupts are already disabled, the sequence would be a write to OMR with
PE modified (ORI/ANDI/MOVEC), followed by an NOP as a delay for
remapping, and then followed by a JMP >long (or another NOP and JMP
<short instead).
3.3.2

Internal I/O Memory Map

The DSP56009 on-chip peripheral modules have their register files programmed to
the addresses in the internal I/O memory range as shown in Table 3-2 on page 3-10.
Note: Location X:$FFFE is the Bus Control Register (BCR) for the DSP56000 core.
Although labelled reserved on the DSP56009, the BCR remains active. The
BCR is cleared by reset and should remain cleared (i.e., do not write to this
location) since the DSP56009 does not make use of the BCR function.
MOTOROLA
Memory, Operating Modes, and Interrupts
DSP56009 Data And Program Memory Maps
; Disable interrupts
; Four instruction cycles guarantee no interrupts
; after interrupts were disabled.
; INST# denotes a one-word instruction, however,
; two one-word instructions can be replaced by
; one two-word instruction.
; Set PEA/PEB bits in OMR
; Allow a delay for remapping,
; meanwhile re-enable interrupts
; 2-word (long) jump instruction (uninterruptable)
; Disable interrupts
; Four instruction cycles guarantee no interrupts
; after interrupts were disabled.
; INST# denotes any one-word instruction, however,
; two one-word instructions can be replaced by
; one two-word instruction.
; Clear PEA/PEB bit in OMR
; Allow a delay for remapping,
; meanwhile re-enable interrupts
; 2-word (long) jump instruction (uninterruptable)
DSP56009 User's Manual 3-9