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AmigaOS 4.0 - About OS4 - Commands

CPU AmigaDOS
Purpose: To set or clear the CPU caches, check for a particular processor, load the ROM image into memory, or set an illegal memory access handler which will output diagnostic information over the serial port at 9600 baud if a task accesses page zero or memory above the acceptable maximum.
Format: CPU [CACHE] [BURST] [NOCACHE] [NOBURST] [DATACACHE] [DATABURST] [NODATACACHE] [NODATABURST] [INSTCACHE] [INSTBURST] [NOINSTCACHE] [NOINSTBURST] [COPYBACK] [NOCOPYBACK] [EXTERNALCACHE] [NOEXTERNALCACHE] [FASTROM] [NOFASTROM] [TRAP] [NOTRAP] [NOMMUTEST] [CHECK 68020 | 68030 | 68040 | 68060 | 68881 | 68882 | MMU | FPU]
Template: CACHE/S, BURST/S, NOCACHE/S, NOBURST/S, DATACACHE/S, DATABURST/S, NODATACACHE/S, NODATABURST/S, INSTCACHE/S, INSTBURST/S, NOINSTCACHE/S, NOINSTBURST/S, COPYBACK/S, NOCOPYBACK/S, EXTERNALCACHE/S, NOEXTERNALCACHE/S, FASTROM/S, NOFASTROM/S, TRAP/S, NOTRAP/S, NOMMUTEST/S, CHECK/K
Path: C:CPU
CPU enables you to adjust various options of the microprocessor installed in your Amiga. CPU will also show the processor and options that are currently enabled.

Many options only work with certain members of the 680x0 processor family as emulated by the PowerPC processor and these are slightly different from previous version of CPU. The 68020 has a special type of memory known as instruction cache. When instruction cache is used, instructions are executed more quickly. The 68030 has two types of cache: instruction and data. The CPU options, outlined below, specify the type of memory to be used. If mutually exclusive options are specified, the safest option is used.

Availability of the options lised below depends on availability of the required hardware.

CACHE Turns on all caches.
NOCACHE Turns off all caches.
BURST Turns off burst mode for both data and instructions.
NOBURST The clock will be <n> pixels wide.
DATACACHE Turns on data cache.
NODATACACHE Turns off data cache.
DATABURST Turns on burst mode for data.
NODATABURST Turns off burst mode for data.
INSTCACHE Turns on instruction cache.
NOINSTCACHE Turns off instruction cache.
INSTBURST Turns on burst mode for instructions.
NOINSTBURST Turns off burst mode for instructions.
COPYBACK Turns on cache copyback.
NOCOPYBACK Turns off cache copyback.
EXTERNALCACHE Turns on external cache.
NOEXTERNALCACHE Turns off external cache.
FASTROM If supported by the MMU, copies data fromn ROM into 32-bit RAM, making access to this data significantly faster. CPU then write-protects the RAM area so that the data cannot be changed.
NOFASTROM Turns off FASTROM.
TRAP Turns on developer specific trap.
NOTRAP Turns off developer specific trap.
NOMMUTEST Allows the MMU settings to be changed without checking to see if the MMU is currently in use.
CHECK The check option, when given with a keyword (68020, 68030, 68040, 68060, 68881, 68882, MMU or FPU) checks for the presence of the keyword.

Example 1:

3.OS4:> CPU
System: PPCIBM PowerPPC 750 FX (emulated MC68020/FPU) (INST: Cache) (External Cache)
Level 1 Cache size: 32768, Level 2 Cache size: 524288


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Disclaimer: Amiga Auckland have prepared the above information for the use of its members based on our experiences and as such is subject to revision at any time. Amiga Auckland cannot guarantee any of the information and cannot be held accountable for any issues that may result from using it.


Copyright 2006 Amiga Auckland Inc. All rights reserved.
Revised: December 24, 2006.