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Section 13: Indirect Operations201
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Indirect Stack and LAST X
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Remember form section 5
that you can specify the stack and LAST X as register addresses by simply pressing
· (decimal point) and X, Y, Z, T, or L
(for LAST X). You can also use the stack and LAST X registers as indirect addresses
by simply pressing g ·
and X, Y, Z, T, or L following the function. For example, to store the number
83.9701 into R11 using stack Z as the indirect address register:
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To recall the number that is now in R11 using the
stack as the indirect address register:
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You should remember that many functions affect the status of the automatic
memory stack (e.g., pushing numbers into the stack), and that when you use the
stack registers as storage registers, the normal stack operation may change the
contents of those registers.
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Indirect Function Control
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Now that you have seen how indirect addressing works, let’s progress a
little and see how some of the other indirect features work in programs.
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Functions requiring the input of an operating specification like
TONE and FIX can use indirect
addressing to specify how the function is to operate. For example,
FIX requires a number from 0 through 9 to specify the
display format. Using indirect addressing, you can store the format specification
number in a register, and then use indirect addressing to complete the function
( FIX g nn). Indirect control
is most useful in programs you write.
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