8x300 design guide - Al Kossow's Bitsavers - Trailing-Edge

The function of the operand fields vary according to the instruction
. to be performed. Table 2-1 provides a summary of operand field
functions in order of instruction called for. More detailed
information on this subject is available in the Signetics 8X300
Programming Manual.
Table 2-1. Operand Field Functions
OPERAND FIELD FUNCTION
I NSTR UCTIONS A B C
BITS 3-7 BITS 8-10 BITS 11-15
MOVE}
ADD
AND
XOR
MOVE}
ADD
AND
XOR
XEC
NZT
XEC
NZT
}
}
XMIT
}
XMIT
}
REGISTER TO REGISTER
REGISTER TO IV BUS ADDRESS
REGISTER TO IV BUS
IV BUS TO REGISTER
IV BUS TO IV BUS
IV BUS TO IV BUS ADDRESS
SOURCE ROTATE DESTINATION
SOURCE LENGTH DESTINATION
REGISTER SOURCE LOCAL ADDRESS
IV BUS SOURCE LENGTH LOCAL ADDRESS
REGISTER
IV BUS ADDRESS
DESTINATION
IV BUS DESTINATION LENGTH
LITERAL CONSTANT
LITERAL
CONSTANT
.JVIP
ADDRESS
2.1.2 Arithmetic Logic Unit
Referring to Figure 2-3, the Arithmetic Logic Unit (ALU) receives
its A-bus inputs from internal registers or I/O (through Rotate/Mask
logic) and its B-bus inputs from either the Instruction Register
CIR8-IR15) or from the Accumulator (a register containing an exact
duplicate of the information contained in the Auxiliary Register,
RO) via a multiplexer. The ALU performs one of four functions on
2-4