S3C84E5/C84E9/P84E9 INSTRUCTION SET
6-1
6 INSTRUCTION SET
OVERVIEW
The instruction set is specifically designed to support large register files that are typical of most S3C8-series
microcontrollers. There are 78 instructions. The powerful data manipulation capabilities and features of the instruction
set include:
A full complement of 8-bit arithmetic and logic operations, including multiply and divide
No special I/O instructions (I/O control/data registers are mapped directly into the register file)
Decimal adjustment included in binary-coded decimal (BCD) operations
16-bit (word) data can be incremented and decremented
Flexible instructions for bit addressing, rotate, and shift operations
DATA TYPES
The CPU performs operations on bits, bytes, BCD digits, and two-byte words. Bits in the register file can be set,
cleared, complemented, and tested. Bits within a byte are numbered from 7 to 0, where bit 0 is the least significant
(right-most) bit.
REGISTER ADDRESSING
To access an individual register, an 8-bit address in the range 0255 or the 4-bit address of a working register is
specified. Paired registers can be used to construct 16-bit data, 16-bit program memory or data memory addresses.
For detailed information about register addressing, please refer to Chapter 2, "Address Spaces."
ADDRESSING MODES
There are seven explicit addressing modes: Register (R), Indirect Register (IR), Indexed (X), Direct (DA), Relative
(RA), Immediate (IM), and Indirect (IA). For detailed descriptions of these addressing modes, please refer to Chapter
3, "Addressing Modes."