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Chapter
2
Getting Started
Summary; This chapter contains a general discussion of the assembly language sys-
tem. A format for the creation of an assembly language program is presented. Topics
such as modules, routines, and memory allocation are discussed, along with methods of
using them effectively. Also discussed is the storage and retrieval of modules on mass
storage.
The thing to remember about the assembly language system is that it has been thoroughly
integrated into the operating system of the 9835A/ B. Once the ROMs have been installed, you
are able immediately to begin programming in assembly language. In addition, you have the
capability to load and store your programs on mass storage, to assemble them separately or
leave them in source form, to execute them from BASIC and pass BASIC variables to them,
and to debug them, including a full pausing and stepping capability.
Developing Routines for Later Use
Most assembly language programs are written with the intent that they will be used many times,
not just at the time they are written. It is for just such program development that the full
capabilities of the assembly language system come into play. The development comes in
several stages. Each stage has its unique requirements and the tools to meet those require-
ments.
The first stage is creation of the source program. This is achieved by the use of the editing
capabilities of the 9835A/B. Additionally, the basic mass storage capabilities of the computer
can be used.
The second stage is the creation of the object (or machine) code. This requires not only an
assembly of the source, but the ability to allocate special locations in memory to hold the newly
created object code.
The third stage is the validation of the routines as written, commonly known as "debugging".
This is enabled by calls from a BASIC driver, followed by application of various debugging
tools provided by the assembly system. The capabilities to pause and step a program have been
extended to assembly language instructions to assist this process.
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