Filter
Top Products
Memory Spaces
DSP56364 24-Bit Digital Signal Processor Users Manual, Rev. 2
3-2 Freescale Semiconductor
Customer code should not use this area. The contents of this program ROM segment is defined by the
bootstrap ROM source code in Appendix A, "Bootstrap ROM".
3.1.1.3 Bootstrap ROM
The bootstrap code is accessed at addresses $FF0000 to $FFF0BF (192 words) in program memory space.
The bootstrap ROM is factory-programmed to perform the bootstrap operation following hardware reset.
The bootstrap ROM can not be accessed in 16-bit address compatibility mode. See Appendix A for a
complete listing of the bootstrap code.
3.1.1.4 Reserved Program Memory Locations
Program memory space at locations $FF00C0 to $FF0FFF and $FF3000 to $FFFFFF is reserved and
should not be accessed.
3.1.2 Data Memory Spaces
Data memory space is divided into X data memory and Y data memory to match the natural partitioning
of DSP algorithms. The data memory partitioning allows the DSP56364 to feed two operands to the Data
ALU simultaneously, enabling it to perform a multiply-accumulate operation in one clock cycle.
X and Y data memory space are similar in structure and functionality, but there are two differences
between them. First, part of Y data RAM may be switched over to program RAM, while X data RAM is
fixed in size. Second, the upper 128 words of each space are reserved for different uses. The upper 128
words of X data memory are reserved for internal I/O. It is suggested that the programmer reserve the
upper 128 words of Y data memory for external I/O. (For further information, see Section 3.1.2.1, "X Data
Memory Space" and Section 3.1.2.3, "Y Data Memory Space")
X and Y data memory space each consist of the following:
• Internal data RAM memory (X data RAM (1K), and Y data RAM (default size is 1.5K, but 0.75K
of Y data RAM can be switched to program RAM)
• (Optionally) Off-chip memory expansion (up to 256K in the 24-bit address mode and 64K in the
16-bit address mode).
3.1.2.1 X Data Memory Space
The on-chip peripheral registers and some of the DSP56364 core registers occupy the top 128 locations of
X data memory ($FFFF80–$FFFFFF in the 24-bit address mode or $FF80–$FFFF in the 16-bit address
mode). This area is called X-I/O space, and it can be accessed by MOVE and MOVEP instructions and by
bit oriented instructions (BCHG, BCLR, BSET, BTST, BRCLR, BRSET, BSCLR, BSSET, JCLR, JSET,
JSCLR, and JSSET). For a listing of the contents of this area, see the programming sheets in Section C.2,
"Programming Sheets".
The reserved X memory space from $FF0000 to $FFEFFF should not be accessed.