dsp56001a Freescale Semiconductor, Inc, dsp56001a Datasheet - Page 76

• Manufacturer Part Number: dsp56001a
• Description: 24-bit Digital Signal Processor
• Manufacturer: Freescale Semiconductor, Inc

DSP56001A
Substituting the DSP56001A for the DSP56001
Software/Application Considerations
Software written for the DSP56001 will generally run unmodified on the DSP56001A. There are,
however, certain differences which should be noted. Users should consider the impact these
differences may have on each application.
Numbers between $8000 and $FFFE (inclusive) are not valid values for loading into the modify
registers (M0–M7) of the address generation unit on the DSP56001. Certain values within this
range, however, enable wrap-around addressing modes on the DSP56001A that are not
supported, and inadvertent enabling of these addressing modes may yield unexpected results.
Do not load the modify registers of the DSP56001A with values from $8000 to $FFFE.
Certain memory locations are designated as reserved on the DSP56001. Accesses to these
memory locations on the DSP56001A will result in unpredictable processor behavior including
the possibility of halting the processor completely. In particular, writes to the following X
memory locations should be avoided on the DSP56001A:
X:$FFDE, X:$FFDF, X:$FFFC, X:$FFFD
On the DSP56001 there is a pipeline delay when using the MOVEP instruction to change the
contents of an address register (Mn, Nn, or Rn). The new contents of the destination address
register will not be available for use during the following instruction (i.e, there is a single
instruction cycle delay).
On the DSP56001A this pipeline delay has been removed. If an address register (Mn, Nn, or Rn)
is directly changed with a MOVEP instruction, the updated contents will be available for use
during the following instruction. DSP56001 software that depends on this pipeline delay must be
modified when moved onto the DSP56001A.
MOVEP instructions to/from Data ALU registers take 2 instruction cycles on the DSP56001. On
the DSP56001A, these instructions take only 1 instruction cycle. DSP56001 software which is
dependent on the timing of this form of the MOVEP instruction must be modified when ported
to the DSP56001A.
4-2
AGU MODIFY REGISTERS
RESERVED MEMORY LOCATIONS
MOVEP TO RN/NN/MN REGISTERS
MOVEP TO/FROM DATA ALU REGISTERS
Freescale Semiconductor, Inc.
For More Information On This Product,
DSP56001A/D, Rev. 1
Go to: www.freescale.com
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