Commodore Plus 4 - Programming modes

PROGRAMMING Your Plus,4 gives you two ways to use BASIC staiements and
MODES commands, in direct mode and indirect mode Direct mode is often
referred to as immediate mode, and indirect mode is also known
as program mode.
DIRECT, or IMMEDIATE MODE, as the name implies, executes state
ments and commands immediately (as soon as you press RETURN y
after typing in a command). You do not type line numbers when using
commands or statements in direct mode. You omy type the command
or statement and press the RETURN key. This mode is used if you
want your computer to perform calculations and give you an immediate
result. Commands such as LIST, SAVE, LOAD, VERIFY and RUN are
usually used in direct node Most (but not all) BASIC statements work
in direct mode.
INDIRECT, or PROGRAM MODE, allows you to organize a series of
BASIC statements into a set of instructions that will be performed in
ihe order that you decide. Each of the lines in the program has a line
number which tells the computer to execute the lines in a certain
order. You ve already seen several examples of program mode in
Chapter 4 Remember that when you use program mode, you must
press RETURN to enter each line of the program into the mem
ory of your Plus/4, if you don t press RETURN , and just go to the
next line, the line you typed has not been entered. Once the program
is in memory, nothing will happen until you enter the RUN command.
The RUN command te'is the Plus/4 to execute the program starting
with the lowest numbered line.
Lines are most often numbered by tens, since you II frequently have
to add lines in different places in the process of writing a program.
You could, if need be, add nine new lines between line 10 and line
20 in a program. However, your Plus/4 features a BASIC command,
RENUMBER, that allows you to add new lines and change the existing
line numbers. This saves a lot of confusion that often occurs when
changing and rearranging lines
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