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Using the 1-Register for Indirect Control
239
0 511
r——
GO @
|
|
|
|
I
>
:
Naturally, you can also press
from the keyboard to begin
execution from the specified (0.
Subroutines can also be addressed and utilized with the I-register.
When
([} is executed in a running program (or pressed from the
keyboard), execution transfers to the specified
and executes the
subroutine. When a[RTN| is then encountered, execution transfers back
to the next instruction after the
(@ and resumes. For example,
with the number 7 stored in the I-register,
[@) causes execution of
the subroutine defined by
7 and (RTN].
l
v
mE0E
//
0 s
//
acsEm
|7
)
=
The simple-to-remember addressing using the I-register is the same
for
and
{@. If the I-register contains zero or a positive
number from 1 through 9,
([ addresses
0 through
9.
When the number in I is a positive 10 through 14,
¥ through
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