UPD75238GJ NEC [NEC], UPD75238GJ Datasheet - Page 150

• Manufacturer Part Number: UPD75238GJ
• Description: 4 BIT SINGLE-CHIP MICROCOMPUTER
• Manufacturer: NEC [NEC]

150
8. INSTRUCTION SET
8.1
(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
(b) A branch is made to a 16-KB space (0000H to 3FFFH), regarding data in a table as the branch address
(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-
PD75238 INSTRUCTIONS
address of a call instruction.
of a branch instruction.
2. When referencing two single-byte instructions with a GETI instruction, only the combina-
3. Branch and subroutine instructions can be referenced by the GETI instruction only when
machine-cycle instruction.
tions listed in the table below are valid.
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 first byte
XCH A,@DL
MOV A,@HL
MOV @HL,A
XCH A,@HL
MOV A,@DE
XCH A,@DE
MOV A,@DL
Instruction of second byte
INCS
DECS
INCS
DECS
INCS
INCS
DECS
INCS
DECS
INCS
INCS
DECS
INCS
DECS
L
L
H
H
HL
E
E
D
D
DE
L
L
D
D
PD75238