GMS30004 Datasheet, PDF (28/158 Pages) Hynix Semiconductor – 4-BIT SINGLE CHIP MICROCOMPUTERS

CHAPTER 3. Instruction
Chapter 3. Instruction
INSTRUCTION FORMAT
All of the 43 instruction in GMS300 series is format in two fields of OP code and
operand which consist of eight bits. The following formats are available with
different types of operands.
é Format
All eight bits are for OP code without operand.
ê Format
Two bits are for operand and six bits for OP code.
Two bits of operand are used for specifying bits of RAM and X-register (bit 1 and
bit 7 are fixed at Ì0Ì)
ë Format
Four bits are for operand and the others are OP code.
Four bits of operand are used for specifying a constant loaded in RAM or Y-
register, a comparison value of compare command, or page addressing in ROM.
ì Format
Six bits are for operand and the others are OP code.
Six bits of operand are used for word addressing in the ROM.
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