
© G.N. Khan ARM Processors/Cores – EE8205: Embedded Computer Systems Page: 8
Three Instruction Sets
ARM Thumb* Jazelle
Instruction Size 32 bits 16 bits 8 bits
Core instructions 58 30
> 60% of Java byte
codes in hardware;
rest in software
Conditional Execution most
Only branch
instructions or in an IT
block
N/A
Data processing
instructions
Access to barrel
shifter and ALU
Separate barrel shifter
and ALU instructions
N/A
Program status
register
Read/write in
privileged mode
No direct access
N/A
Register usage
15 general purpose
registers + pc
8 general purpose
registers + 7 high
registers + pc
N/A
* LM3S811 (a Cortex M3 variation) uses the Thumb2 set
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