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Getting Started
9
Overview
At this point, there are three fundamental structures to be explained: programs, modules, and
routines.
A program is the set of source statements from which the object (or machine) code is gener-
ated. The assembly source statements are extensions to the BASIC language which is used in
the 9835A/ B. The statements themselves are stored in the machine as part of the BASIC
program in which they reside. At some point, you must take the assembly source statements
and assemble them into object code, in order that they can be run. The object code is stored in
a specified location in the machine.
A module is a subset of the object code. It is a means of separating and identifying parts of the
code so that those parts may be used individually (as in mass storage operations). There may
be any number of modules present at anyone time, limited only by the amount of memory
allocated for object code.
A routine is a "callable" section of a module. It is analogous to the subprogram in BASIC. It
has a named entry point, possibly·a parameter list, and
(if
programmed correctly) a return. A
module may contain any number of routines, again limited only by the amount of memory
allocated to hold the object code.
In short, the usefulness of each structure is as follows -
• Programs contain assembly language source code.
• Modules contain object code to be loaded from or stored on mass storage.
• Routines are executable sections of object code.
Program Creation
The first matter which is likely to concern you about the assembly language system is how to
create an assembly language program.
In general, the process of creating an assembly language subprogram consists of the following
steps -
1.
Enter and store the source code (program).
2. Create an area in memory which will ultimately contain the object code.
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