titus-larsen-titus-1981-apple-interfacing

CHAPTER
The purpose of the experiments in this section is to provide
with some hands-on experience in the use of latched oui:put port and
three-state input circuits that were developed in the
chapters. You find that these experiments use simple
series devices to transfer data to and from the Apple.
of circuits will be
complete list parts that will be is in Appendix B.
·we have assumed that you have had some experience in breadboarding
simple logic circuits, and that you are familiar with the basic
breadboarding skills. Some auxiliary fonctions will be required in
the experiments to both monitor logic states and to generate them.
In general, we use lamp monitors or LEDs to indicate logic one (on)
and logic zero (off), logic svvitches to generate logic levels, and debounced
pu.lsers, or pulsers for short, to generate logic levels with
dean noise-free transitions between the logic levels. Some simple
schematic diagrams of these types of circuits are provided in the
Appendix. If you do not wish to build these circuits, they can be
breadboarded separately, or similar functions can be purchased from
companies such as E & L Instruments, Derby, CT 06418 or PAC­
CON[, Redmond, WA 98052. In general, most of the experiments iJ1
this book can be done with a few simple circuits.
We have provided one experiment that illustrates the use of a
decoder circuit for device addressing. While many decoder schemes