
150
μ
PD75238
8. INSTRUCTION SET
8.1
μ
PD75238 INSTRUCTIONS
(1) GETI instruction
The GETI instruction references a two-byte table in the program memory and performs the following
three types of operations. This single-byte instruction is very useful in reducing the number of program
steps.
(a) A subroutine call is made to a 16-KB space (0000H to 3FFFH), regarding data in a table as the call
address of a call instruction.
(b) A branch is made to a 16-KB space (0000H to 3FFFH), regarding data in a table as the branch address
of a branch instruction.
(c) Data in a table is executed as a double-byte instruction excluding BRCB and the CALLF instructions.
(d) Data in a table is executed as the instruction code of two single-byte instructions.
As shown in Fig. 3-2, the tables to be referenced by a GETI instruction are located at addresses 0020H
to 007FH in the program memory. That is, data can be set in up to 48 tables.
When describing a table address as an operand, describe an even address.
Cautions 1. A two-byte instruction which can be referenced by a GETI instruction must be a two-
machine-cycle instruction.
2. When referencing two single-byte instructions with a GETI instruction, only the combina-
tions listed in the table below are valid.
3. Branch and subroutine instructions can be referenced by the GETI instruction only when
the addresses of the destination and subroutine call are in the 16K-byte space (0000H to
3FFFH). A branch or subroutine instruction to an address from 4000H to 7F7FH cannot be
referenced by the GETI instruction.
Instruction of second byte
Instruction of first byte
MOV A,@HL
MOV @HL,A
XCH A,@HL
MOV A,@DE
XCH A,@DE
MOV A,@DL
XCH A,@DL
INCS
DECS
INCS
DECS
INCS
L
L
H
H
HL
INCS
DECS
INCS
DECS
INCS
E
E
D
D
DE
INCS
DECS
INCS
DECS
L
L
D
D