APR3SLASHD datasheet(76/101 Pages) NXP

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4-2

DSP56001A/D, Rev. 1

MOTOROLA

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.

AGU MODIFY REGISTERS

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.

RESERVED MEMORY LOCATIONS

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

MOVEP TO RN/NN/MN REGISTERS

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

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 TO/FROM DATA ALU REGISTERS

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.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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