These instructions have the same word format as the indexable
instructions. Since they operate on the index register location, x, they
cannot be indexed.
_Skip on Negative index_ (10 usec.)
snx x Y Operation Code 46
The number in octal digits 7 through 11 of the instruction word is added
to the C(x). This addition is done in the 15 bit Index Adder using 1's
complement arithmetic. If, after the addition, the sum is negative, the
Program Counter is advanced one extra position and the next instruction
in the sequence is skipped. The contents of octal digits 0-5 of the
index register location are unaffected by this instruction.
_Skip on Positive index_ (10 usec.)
spx x Y Operation Code 44
The number in octal digits 7 through 11 of the instruction word is added
to the C(x). This addition is done in the 15 bit Index Adder using 1's
complement arithmetic.
If, after the addition, the sum is positive, the Program Counter is
advanced one extra position and the next instruction in the sequence is
skipped. The contents of octal digits 0-5 of the index register location
are unaffected by this instruction.
_Load Index Register_ (10 usec.)
lir x Y Operation Code 14
The octal digits 7 through 11 (Y) of the instruction will replace the
corresponding digits of the memory register specified by x. Octal digit
6 of the memory register will be left clear. Digits 0-5 of the memory
register are unchanged.
_Deposit Index Adder_ (10 usec.)
dia x Y Operation Code 16
The C(IA) replace the octal digits 7 through 11 of memory location Y.
Octal digit 6 of Y is cleared. Digits 0 through 5 of Y are left
unchanged. The x portion of the instruction is ignored.