Motorola MPC533 Reference Manual page 1033

Appendix G
MPC534 Compression Features
The contains a number of code compression features not found in the that function from
the burst buffer controller module (BBC) module of the device.
The BBC's instruction code decompressor unit (ICDU) is responsible for on-line
(previously compressed) instruction code decompression in the decompression on mode.
The ICDU contains a -Kbyte RAM (DECRAM) that is used for decompressor vocabulary
table storage when compression is enabled or as general-purpose memory on the U-bus
when compression is disabled.
The code compression features of the are different than the
code compression of the MPC556.
G.1 ICDU Key Features
The following are instruction code decompression unit key features:
• Instruction code on-line decompression is based on an "instruction class" algorithm.
• There is no need for address translation between compressed and non-compressed
address spaces — ICDU provides the "next instruction address" to the RCPU.
• In most cases, instruction decompression takes one clock.
• Code decompression is pipelined:
— No performance penalty during sequential program flow execution
— Minimal performance penalty due to change of program flow execution
• Two operation modes are available: decompression on and decompression off.
Switches between compressed and non-compressed user application software is
possible.
• Adaptive vocabularies scheme is supported; each user application can have its own
optimum vocabularies.
MOTOROLA
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
NOTE
Appendix G. MPC534 Compression Features G-1