MPC555CME Freescale Semiconductor, MPC555CME Datasheet - Page 180

• Manufacturer Part Number: MPC555CME
• Description: KIT EVALUATION FOR MPC555
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC555CME

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Processor To Be Evaluated: MPC555
• Data Bus Width: 32 bit
• Interface Type: RS-232
• For Use With/related Products: MPC555
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

4.3.2 Model Limitations
4.3.3 Vocabulary Based Instruction Compression Algorithm
MPC555
USER’S MANUAL
No address arithmetic is allowed, because the address map changes during compres-
sion and no software tool can identify address arithmetic structures in the code.
The code compression algorithm is based on creating vocabularies of frequently
appearing PowerPC RISC instructions or instruction halves and replacing these
instructions with pointers to the vocabularies.
Compressed and bypass field lengths may vary. An example of compressed code is
shown in
Compression of the instructions in a vocabulary may be in one of the following modes.
• Slight changes in the core and existing RISC development tools — compilers,
• Compressed address space is up to four Megabytes (4 Mbytes).
• Branch displacement from its target:
1. Compression of the whole instruction into four vocabulary byte pointers. The
2. Compression of a combination of the instruction’s bytes into vocabulary point-
3. Bypass of the whole instruction. No compaction permitted.
/
simulators, manually coded libraries.
— Conditional branch displacement is up to two Kbytes (2 Kbytes).
— Unconditional branch displacement is up to two Mbytes (2 Mbytes).
MPC556
four compacted bytes may start on any bit location. Four of the decoded bits
and another bit for starting from the left or right side of the address location de-
termine the bit location for the byte start
ers and bypass of the other byte(s). Bypass is the placing of the field’s uncom-
pressed instruction information into the compressed code.
Figure
Branch displacement is hardware limited. The compiler can enlarge
the branch scope by creating branch chains.
4-2.
Rev. 15 October 2000
BURST BUFFER
NOTE
MOTOROLA
4-4