RDC
®
RISC DSP Controller
R8810LV
RDC Semiconductor Co.
Rev:1.1
Subject to change without notice
17
Execution Unit
General Register
The R8810 has eight 16-bit general registers. And the AX,BX,CX,DX can be subdivided into two 8-bit register (AH,AL,BH,
BL,CH,CL,DH,DL). The functions of these registers are described as follows.
AX
: Word Divide , Word Multiply, Word I/O operation.
AH
: Byte Divide , Byte Multiply, Byte I/O , Decimal Arithmetic, Translate operation.
AL
: Byte Divide , Byte Multiply operation.
BX
: Translate operation.
CX
: Loops, String operation
CL
: Variable Shift and Rotate operation.
DX
: Word Divide , Word Multiply, Indirect I/O operation
SP
: Stack operations (POP, POPA, POPF, PUSH, PUSHA, PUSHF)
BP
: General-purpose register which can be used to determine offset address of operands in Memory.
SI
: String operations
DI
: String operations
Segment Register
R8810 has four 16-bit segment registers, CS, DS, SS, ES. The segment registers contain the base addresses (starting location)
of these memory segments, and they are immediately addressable for code (CS), data (DS & ES), and stack (SS) memory.
CS (Code Segment)
: The CS register points to the current code segment, which contains instruction to be fetched. The
default location memory space for all instruction is 64K. The initial value of CS register is 0FFFFh.
Accumulator
Base Register
Count/Loop/Repeat/Shift
Data
Stack Pointer
Destination Index
Base Pointer
Source Index
AX
BX
CX
DX
Data
Group
Index Group
and
Pointer
GENERAL REGISTERS
AH
BH
CH
DH
AL
BL
CL
DL
SP
BP
SI
DI
0
7
8
15
High
Low