HMS38112 Datasheet, PDF (40/73 Pages) List of Unclassifed Manufacturers – 4-BIT SINGLE CHIP MICROCOMPUTERS

Chapter 4. Instruction
CHAPTER 4. Instruction
INSTRUCTION FORMAT
All of the 43 instruction in HMS38112/39112 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.
4-1