RCA 70/46 - Test under Mask (TM)

Test Under Mask
(TM)
General Description
Format
(SI)
Condition Code
Interrupt
Action
Note
Logical
Instructions
• The operand (byte) specified by the first address (B1/D
1
) is tested
against the immediate I field (byte) as a mask. The result determines the
condition code. The I field is used as an eight-bit mask and is made to
correspond one-for-one
with the bits of the byte in main memory that is
specified by the first address.
A
bit in the byte being examined is said to be selected when the corre-
sponding mask bit is a one. When the mask bit is a zero, the bit in main
memory is ignored.
91
o 7 8
15 16 19 20
31
• 0 - selected bits all zero or mask is all zero.
1 - selected
hits mixed zero and one.
2-not used.
3 - selected bits all one's.
• Address error:
Addressing.
• The operands are unaltered.
178