en.
The SHOW instruction allows blocks of text to be shown extremely fast, particularly if your
computer has a hard disk or a RAM disk and you use this facility to store the blocks of text.
The picture frequency can be faster than 0.1 s and you can program special-effect-like anima-
tion sequences. The program example supplied demonstrates the use of this special effect.
KODAK S-RA2500 Editing System 1.0 User Manual Page: 48
B-2 Second lesson
As you might expect, the second lesson is somewhat more difficult but it is also more interest-
ing. The typical program prepared in the first lesson had a linear structure and its progression
was identical regardless of the circumstances: start from the beginning and continue to the
d .
The Editing System can, however, also be used to write programs which progress differe
tly depending on user input. This requires what are referred to as „conditional branch instructi
ns“ and we shall examine these in the next exam
e.
B-2.1 Structural characteristics
Before becoming involved in detailed descriptions, let us consider some of the fundamental
aspects of programs in which branching occurs.
The demonstration program supplied on your diskette shows a typical application for program
branching in which the user can select from a list those items of information which interest him
at that particular moment.
The structural elements of such a program are as follows:
- Main loop
- Subroutines
The program performs most of its activities as it goes through the main loop. It polls the user
input and continuously repeats this process until such input eventually occurs. The input is
evaluated and, depending on its type, causes the system to go into one of the subroutines, run
the subroutine and then return to the main loop when the subroutine has been completed. Fig-
ure B-4 illustrates this arrangement. Although programs can obviously be made much more
complex, in the following example we shall adopt this structure and test its capabilities on a
straightforward problem statement.
KODAK S-RA2500 Editing System 1.0 User Manual Page: 49
Program s
t
User inpu
