CF Field
CG Field
CY Field
CD
=
IIII
(I)
This specifies the I register as the destination for the ALU output.
This field controls the ALU-A register entry for High-Low 4 bit gating
and straight crossed switching.
CF
=
0000 (0)
This specifies the ALU-A register entry will be blocked and forced to
zeros. (See example lOA, page 26.)
CF
=
0001 (L)
This specifies the ALU-A register entry Low 4 bits will be gated and the
High 4 bits will be blocked and forced to zeros. (See example lOA, page 26.)
OF
~
0010 (H)
This specifies the ALU-A register entry High 4 bits will be gated and the
Low 4 bits will be blocked and forced to zeros. (See example lOA, page 26.)
CF
=
0011 (Straight)
This specifies the AL U-A register entry High and Low 4 bits will be gated.
(See example lOA, page 26.)
CF
=
0100 (Stop)
This specifies a machine stop function. The machine stops at the end of the
cycle prior to the microword containing this instruction. The WX register
contains the address of this microword.
OF
=
0101 (XL)
This specifies the ALU-A register entry will cross the High 4 bits into the
Low 4 bits and the Low 4 bits into the High 4 bits. Then it gates the Low 4
bits to the ALU and blocks the High 4 bits, forcing them to zeros. (See ex-
ample lOB, page 26.)
CF
=
0110 (XH)
This specifies the ALV-A register entry will cross the High 4 bits into the
Low 4 bits and the Low 4 bits into the High 4 bits.
It
then gates the High 4
bits to the ALU and blocks the Low 4 bits, forcing them to zeros. (See ex-
ample lOB, page 26.)
CF
=
0111 (X)
This specifies the ALU-A register entry will cross the High 4 bits into the
Low 4 bits and the Low 4 bits into the High 4 bits. Then both the High and
Low 4 bits are gated to the ALU. (See example lOB, page 26.)
This field controls the ALU-B entry High-Low 4 bit gating.
CG
=
0000 (0)
This specifies the ALU-B register entry will be blocked and forced to
zeros. (See example 11, page 27.)
CG
=
0001 (L)
This specifies the ALU-B register entry Low 4 bits will be gated, and the
High 4 bits will be blocked and forced to zeros. (See example 11, page 27.)
CG
=
0010 (H)
This specifies the ALU-B register entry High 4 bits will be gated, and the
Low 4 bits will be blocked and forced to zeros. (See example 11, page 27.)
This field controls the ALU true-complement and binary-decimal functions.
CY
=
0000
(+)
This specifies a true binary add.
IBM Con/iJentitll
11