INTRODUCTION



     Problem 1.
        MOVEBYTE V,84
        MOVEWORD H,85

     Problem 2.
        MOVEBYTE 84,V
        MOVEWORD 85,H

     And yet another concept before we leave assembly language. One
of the most powerful features of an assembler is its ability to handle
equated symbols. The real beauty of this, aside from producing more
readable code, is that you can change all references to a location or
value or whatever by simply changing a single equate in your source
code. Thus, if somewhere near the beginning of our source program
we had coded the following two lines:

     ROWCRS = 84 ; address of ROW CuRSor
     COLCRS = 85 ; address of COLumn CuRSor

then we could have "solved" the problems thus:

     Problem 1.
        MOVEBYTE V,ROWCRS
        MOVEWORD H,COLCRS

     Problem 2.
        MOVEBYTE ROWCRS,V
        MOVEWORD COLCRS,H

And I believe that this looks as elegant and readable as any of the
higher level languages! In fact, it looks more readable than most of the
examples given above. To be fair, though, we should note that all of
the examples could have been made more readable by substituting
variable names instead of the absolute numbers "84" and "85," but the
overhead of declaring and assigning variables is sometimes not worth
it for languages such as BASIC and PILOT.
     Luckily, the remaining languages (Forth, C, and Pascal) all have
a means of declaring constants (akin to the assembly language equate)
which has little or no consequential overhead. So go ahead--be the
oddball on your block and make your code readable and
maintainable. It may lose you friends, but it might help you land a job.

Happy Mapping
Well, we made it. I hope you now at least have an idea of what to do to
modify and examine various memory locations in all of the languages
shown. Virtually all of the many locations mapped in this book will fall
into one of the two categories examined: they will involve changing or
examining either a single byte or a double byte (word, integer,
address, etc.). Follow the models shown here, and you should have
little trouble effecting your desires.
     For those few locations which do not follow the above patterns