YACC1 – Instruction Set

This is a total guess

Bit 7 = 1 

These are the 8 two register instructions where:

Bit[6:4] are instruction code

Bit[3:2] are destination register, Bit[1:0] are source register

MOV Rx Ry    1000 xx yy  Cop

ADD Rx Ry     1001 xx yy

SUB Rx Ry      1010 xx yy

1011 xx yy

1100 xx yy

1101 xx yy

1110 xx yy

1111 xx yy

 

Bit 7 = 0, Bit 6 = 1

These are the 16 one register operations where:

Bits[5:2] are the the instruction code

Bits[1:0]are the register

 

Bit 7 = 0, Bit 6 =  0

These are the 64 no register operations where:

Bits[5:0] are the instruction code

 

**** This might be further divided into one and two byte instructions

YACC 1 Instruction Set

Complete list of YACC1 Instructions

Instruction	Hex	Description	Operands	Implemented
MOV Rd Rs	1000 XX YY	Copy contents of Rs (source) to Rd (destination)	XX,YY = Register Number 00 - Register 0 01 - Register 1 10 - Register 2 11 - Register 3	No
Add Rd Rs	1001 XX YY	Add contents of Rs to Rd		no
Sub Rd Rs	1010 XX YY			no
AND Rd Rs	1011			no
OR Rd Rs	1100			no
XOR Rd Rs	1101			no
NAND Rd Rs	1110			no
NOR Rd Rs	1111			no
				no