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
InstructionHexDescriptionOperandsImplemented
MOV Rd Rs1000 XX YYCopy 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 Rs1001 XX YYAdd contents of Rs to Rdno
Sub Rd Rs1010 XX YY
no
AND Rd Rs1011no
OR Rd Rs1100no
XOR Rd Rs1101no
NAND Rd Rs1110no
NOR Rd Rs1111no
no