EM78468
8-BIT Microcontroller
4.12 Instruction Set
Each instruction in the instruction set is a 13-bit word divided into an OP code and one or
more operands. Normally, all instructions are executed within one single instruction cycle
(one instruction consists of 2 oscillator periods), unless the program counter is changed
by instruction "MOV R2,A", "ADD R2,A", or by instructions of arithmetic or logic operation
on R2 (e.g. "SUB R2,A", "BS(C) R2,6", "CLR R2", ⋅⋅⋅⋅). In this case, the execution takes
two instruction cycles.
If for some reasons, the specification of the instruction cycle is not suitable for certain
applications, try modifying the instruction as follows:
Execute within two instruction cycles the "JMP", "CALL", "RET", "RETL", & "RETI"
instructions, or the conditional skip instructions ("JBS", "JBC", "JZ", "JZA", "DJZ",
"DJZA") which were tested to be true. Also execute within two instruction cycles the
instructions that are written to the program counter.
Additionally, the instruction set offers the following features:
(1)Every bit of any register can be set, cleared, or tested directly.
(2)The I/O register can be regarded as general register. That is, the same instruction can
operate on I/O register.
The symbol "R" represents a register designator that specifies which one of the registers
(including operational registers and general purpose registers) is to be utilized by the
instruction. "b" represents a bit field designator that selects the value for the bit that is
located in the register "R", and affects operation. "k" represents an 8 or 10-bit constant or
literal value.
Product Specification (V1.1) 04.11.2005
(This specification is subject to change without further notice)
• 53
ELAN [ ELAN MICROELECTRONICS CORP ]
