s3c4510b Samsung Semiconductor, Inc., s3c4510b Datasheet - Page 29

• Manufacturer Part Number: s3c4510b
• Description: 16/32-bit Risc Microcontroller
• Manufacturer: Samsung Semiconductor, Inc.

S3C4510B
INSTRUCTION LENGTH
Instructions are either 32 bits long (in ARM state) or 16 bits long (in THUMB state).
Data Types
ARM7TDMI supports byte (8-bit), half-word (16-bit) and word (32-bit) data types. Words must be aligned to four-
byte boundaries and half words to two-byte boundaries.
OPERATING MODES
ARM7TDMI supports seven modes of operation:
— User (usr):
— FIQ (fiq):
— IRQ (irq):
— Supervisor (svc):
— Abort mode (abt):
— System (sys):
— Undefined (und):
Mode changes may be made under software control, or may be brought about by external interrupts or exception
processing. Most application programs will execute in User mode. The non-user modes known as privileged
modes-are entered in order to service interrupts or exceptions, or to access protected resources.
The normal ARM program execution state
Designed to support a data transfer or channel process
Used for general-purpose interrupt handling
Protected mode for the operating system
Entered after a data or instruction prefetch abort
A privileged user mode for the operating system
Entered when an undefined instruction is executed
PROGRAMMER'S MODEL
2-3