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      The TMS320C2x provides a total of 544 16-bit words of on-chip data
      RAM, of which 288 words are always data memory and the remaining 256
      words may be configured as either program or data memory. The
      TMS320C25 also provides 4K words of maskable program ROM.

MEMORY MAPS
      The TMS320C2x provides three separate address spaces for program
      memory, data memory, and I/O as shown below. These spaces are
      distinguished externally by means of the
      __  __      __
      PS, DS, and IS (program, data, and I/O space select) signals.
           __  __  __      ____
      The  PS, DS, IS, and STRB signals are only active when external
      memory is being addressed. During an internal addressing cycle,
      these signals remain inactive high, thus preventing conflicts in
      memory addressing, e.g., when block B0 is configured as program
      memory.

      The on-chip memory blocks B0, B1, and B2 are comprised of a total
      of 544 words of RAM. Program/data RAM block B0 (256 words) resides
      in pages 4 and 5 of the data memory map when configured as data RAM
      and at addresses >FF00 to >FFFF when configured as program RAM.
      Block B1 (always data RAM) resides in pages 6 and 7, while block B2
      resides in the upper 32 words of page 0. Note that the remainder of
      page 0 is composed of the memory-mapped registers and internally
      reserved locations, and pages 1-3 of the data memory map consist of
      internally reserved locations. The internally reserved locations may
      not be used for storage, and their contents are undefined when read.
      See also "memory-mapped registers".

      The on-chip RAM is mapped into either the 64K-word data memory or
      program memory space, depending on the memory configuration. The
      CNFD/CNFP instructions are used to configure block B0 as either data
      or program memory, respectively. The BLKP (block move from program
      memory to data memory) instruction may be used to download program
      information to block B0 when it is configured as data RAM. Then a
      CNFP (configure block as program memory) instruction may be used to
      convert it to program RAM (see also "memory management"). Regardless
      of the configuration, the user may still execute from external
      program memory. Note that when accessing internal program memory,
      external control lines remain inactive.

      Reset configures block B0 as data RAM. Due to internal pipelining,
      when CNFD or CNFP instruction is used to remap  RAM block B0, there
      is a delay before the new configuration becomes effective. This
      delay is one fetch cycle if execution is from internal program RAM.
      On the TMS32020, adelay of one fetch cycle occurs if execution is
      from internal program memory. On the TMS320C25, there is a delay of
      two fetch cycles if execution is from ROM or external program
      memory. This is particularly important if program execution is from
      the locations around >FF00. Accordingly, a CNFP  instruction must
      be placed at program location >FEFD in external memory if execution
      is to continue from the first location in block B0. If a CNFP is
      placed at location >FEFD, and the instruction at >FEFF is a two-word
      instruction, the second word of the instruction will be fetched from
      the first location in block B0. If execution is from above location
      >FF00 and block B0 is reconfigured, care must be taken to assure
      that execution resumes at the apprpriate point in a new
      configuration.

      On-chip program ROM on the TMS320C25 is located in the lower 4K
      words of program memory when selected by setting
         __              __
      MP/MC = 0. When MP/MC = 1, the lower 4K words of program memory are
      external.

MEMORY MAPS AFTER CNFD INSTRUCTION

            PROGRAM                PROGRAM                  DATA
 >0000+--------------+ >0000+--------------+ >0000+--------------+
      |  INTERRUPTS  |      |  INTERRUPTS  |      |   ON-CHIP    |
      | AND RESERVED |      | AND RESERVED |      | MEMORY-MAPPED|
 >001F|  (EXTERNAL)  | >001F|(ON-CHIP ROM) |      |   REGISTERS  |
      |--------------|      |--------------| >0005|--------------|
 >0020|              | >0020|   ON-CHIP    | >0006|   RESERVED   |PG 0
      |              | >0FAF|     ROM      | >005F|--------------|
      |              |      |--------------| >0060|    ON-CHIP   |
      |              | >0FB0|   RESERVED   | >007F|   BLOCK B2   |
      |              | >0FFF|              | >0080|--------------|
      |              |      |--------------| >01FF|   RESERVED   |PG1-3
      |              | >1000|              |      |--------------|
      |   EXTERNAL   |      |              | >0200|    ON-CHIP   |
      |              |      |              | >02FF|   BLOCK B0   |PG4-5
      |              |      |   EXTERNAL   |      |--------------|
      |              |      |              | >0300|    ON-CHIP   |
      |              |      |              | >03FF|   BLOCK B1   |PG6-7
      |              |      |              |      |--------------|
      |              |      |              | >0400|              |PG 8-
      |              |      |              |      |   EXTERNAL   | 511
 >FFFF+--------------+ >FFFF+--------------+ >FFFF+--------------+
        IF MP/MC = 1          IF MP/MC = 0
                   TMS320C25 ONLY


MEMORY MAPS AFTER CNFP INSTRUCTION

            PROGRAM                PROGRAM                  DATA
 >0000+--------------+ >0000+--------------+ >0000+--------------+
      |  INTERRUPTS  |      |  INTERRUPTS  |      |   ON-CHIP    |
      | AND RESERVED |      | AND RESERVED |      | MEMORY-MAPPED|
 >001F|  (EXTERNAL)  | >001F|(ON-CHIP ROM) |      |   REGISTERS  |
      |--------------|      |--------------| >0005|--------------|
 >0020|              | >0020|   ON-CHIP    | >0006|   RESERVED   |PG 0
      |              | >0FAF|     ROM      | >005F|--------------|
      |              |      |--------------| >0060|    ON-CHIP   |
      |              | >0FB0|   RESERVED   | >007F|   BLOCK B2   |
      |              | >0FFF|              | >0080|--------------|
      |              |      |--------------| >01FF|   RESERVED   |PG1-3
      |              | >1000|              |      |--------------|
      |   EXTERNAL   |      |              | >0200|   DOES NOT   |
      |              |      |              | >02FF|     EXIST    |PG4-5
      |              |      |   EXTERNAL   |      |--------------|
      |              |      |              | >0300|    ON-CHIP   |
 >FEFF|              | >FEFF|              | >03FF|   BLOCK B1   |PG6-7
      |--------------|      |--------------|      |--------------|
 >FF00|    ON-CHIP   | >FF00|    ON-CHIP   | >0400|              |PG 8-
      |   BLOCK B0   |      |   BLOCK B0   |      |   EXTERNAL   | 511
 >FFFF+--------------+ >FFFF+--------------+ >FFFF+--------------+
        IF MP/MC = 1          IF MP/MC = 0
                   TMS320C25 ONLY