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CHAP1.TXT
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CHAP01.TXT
Version 1.01 01/29/85
Leonard Gilberg 74126,2044
Robert Flagg 72466,2332
THE JOYS OF ASSEMBLY
This "Cookbook" is the brainchild of Robert Flagg
[72466,2332], Leonard Gilberg [74126,2044], Bonnell Frost
[74076,223] and others, who, with the blessing of Frank
Fallon (SYSOP), felt it would be helpful if some members of
the Sig, new and otherwise, had an oppor tunity to see the
struggles of members new to CP/M learning the ins and outs of
using ASM, LASM3 and/or ZASM. Some of the "Recipes" here are
the contribution of several members of the Sig who are grateful
to have the opportunity to pass along information given to them
by more ex perienced members when they were struggling too.
Too often, members are afraid to ask for help,
thinking that the question is too basic or that they will appear
"dumb". The only dumb question is the unasked one because
there are always others eager to pass along advice and excited
about the opportunity to repay the favors given them in the
beginning, by helping someone else along.
Should this Cookbook be approved and placed in "use", we
will all be happy to have been a part of it, especially, if it is
of help to any one.
Normally, files with the extension .ASM, when down-
loaded, are transformed into files with the extension .COM after
the application of some version of ASM.COM and LOAD.COM. At that
time, they are ready to run as in the case of any other .COM
file you have by simply typing the filename without the .COM
extension.
In some cases, for example where the program is
installed as a patch, in WordStar for instance, you will stop
after the use of ASM so that the file will have a .HEX extension.
You will not, in such cases, use the LOAD.COM procedure. There
are some rarer variations of this, but they are beyond the scope
of this discussion.
For the sake of terminology, the .ASM is referred to
as the "Source Code" file and the .COM file as the "Object Code"
file.
You may one of those who "almost" understand what is
being said about a particular program or action, but really are
not sure because some of the words are strange. You may be
afraid that if you ask what the word or words mean, everyone
will think you're so dumb they won't want to talk to you anymore.
Perish the thought! For those of you who feel you need it, here
is our attempt at some sort of table of definitions.
DEFINITIONS
ALGORITHM - Generally, a special method of solving a
certain kind of problem.
ASSEMBLERS - Those programs, such as ASM.COM, LASM.COM &
ZASM.COM, which take an Assembly Language Source File and create
two other files--the object code .HEX file and the diagnostic
.PRN file.
COMPILER - A language translator which takes as input source code
in a high-level language such as Fortran, C, Pascal, or Cobol and
generates as output either assembler-input code or object code
directly.
DDT - An utility program, by Digital Research Institute (DRI),
supplied with CP/M and used to "debug" programs. Hence the
name DDT (cute, huh?). Used to break a program down into its
8080 mnemonics so that those who know what they are can make the
changes desired. DDT is RAM-memory oriented.
DU - Another utility program, designed by Ward Christensen
which works, essentially, the same as DDT, with a little
different configuration, and now followed by DUU.COM. DU is
oriented to work on disk memory.
ENTRY POINTS - The specific location in a program where an
Overlay or other modification to the program begins.
GENERIC - A non-specific class, general in nature.
HEX - A "shorthand" reference to Hexidecimal values, usually
known as Intel format, and created by the ASM program. Also
used as a file extension, i.e., Filename.HEX. Also, a situation
which exists when Mother Nature discovers that you forgot to put
surge protectors on your equipment and calls down the elements
to teach you better.
INITIALIZATION - A command or sequence of commands which readies
equipment or a program for execution as desired. Normally used
in connection with setting equipment, such as printers, to their
default values.
INTERACTIVE - In the computereze climate, this is usually a point
in a program where you input information from the keyboard
or "interact" with the program.
LANGUAGE - A word which describes the particular type of instruc
tion to a computer. The "language" must be structured in such
a way that the computer "understands" and is able to convert
the instructions contained in the "language" into object code.
Examples could be Assembly, Cobol, Fortran, C, Pascal, Forth,
etc.
LOAD - The program, usually supplied with CP/M, which takes the
.HEX file generated by the ASM program and converts it into a
.COM program ready to run. LOAD.COM and MLOAD.COM are examples.
MACHINE LANGUAGE - Binary code, a series of 1's and 0's, which is
the only instruction that a computer understands. Every other
language is either translated, interpreted, compiled, assembled
or loaded so as to, ultimately, reach machine language.
MICROPROCESSOR - Usually, a silicon chip (such as Intel's 8080 or
Zilog Z-80, such as is used in the Kaypro).
MNEMONICS - "Short-hand" or abbreviated instructions required by
a particular language processor in order for the compiler or
assembler to generate object code.
OBJECT FILE - The file which contains the binary code which you
always wanted when you started with the "Source File." Usually
this is a .HEX or a .COM file.
OFFSET - Has more than one meaning. In 8 bit operation, such as
CP/M, usually means a hexidecimal position or address other than
the "usual" or "expected" location or address. Normally given as
an auxilliary address in the command where it is used.
OVERLAY - A method allowing a group of changes to be made in an
existing program. The "overlay" program is typically a smaller
program which, when "overlaid" on an existing program, changes
part of the instructions in the existing program. Overlays are
commonly used to configure "generic" software to enable it to run
on specific hardware setups.
PATCH, PATCHING - The process of changing a program byte-by-byte.
Often used when smaller changes are required to customize a
program.
SCREEN CLEARING - The act of giving or causing to be given a
command or series of commands which cause the CRT to clear or
become blank.
SEQUENCE - A series of commands, structured to give a computer
specific instructions to accomplish. Usually, must be given in a
pre-set or predetermined order.
SOURCE FILE - The program written in a human-understandable
language which assemblers or compilers will convert to machine-
understandable object code.
SPECS - Short for specifications.
SUB - An extension (.SUB) for a source file of commands for the
SUBMIT or EX program.
ZCPR - A Z80 Command Processor replacement for the CP/M Console
Command Processor (CCP) which performs a new and different set of
commands as well as the familiar CP/M commands. Author is Rick
Conn.
e to enable it to