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THE APPLE CONNECTION by James W. Coffron
Note: This article was scanned using OCR from the Fall 1985 CCCE Newsletter. Please contact us if you identify any OCR errors.
Sybex has been publishing high quality books for computer users for some time, and The Apple Connection continues this pattern. The main thrust of the book is to provide users with an introduction to computer interfacing. The book is elegant in its simplicity yet quite thorough in its treatment of computer interfacing projects.
The first several chapters are devoted to an introduction to computer architecture and the use of the expansion slots for interfacing. To this end, the book uses the creative Microprocessor Systems I/O card (CMS I/O card). While the name and address of the manufacturer of the card are given, no cost. is provided. Without the card to work with the first three chapters are difficult to comprehend. Considering that the board is used as a trainer, it might well have been wise to show the reader how to build such a board from components. The balance of the first three chapters deals with the programming needed to access the peripheral slots. Clear, concise and detailed presentations are given to such topics as the means of addressing each slot, interpretation and weighting of the data lines and the BASIC commands needed to perform these tasks. Additionally, several BASIC programs are provided along with flow charts to demonstrate the desired concepts. These programs include turning on a Light Emitting Diode (LEO), turning on the LED's in a wave type pattern, slot detection and a decimal to binary conversion program.
Several interfacing problems are examined in the subsequent portions of the book. The design of the hardware and software for a home security system is most impressive. The author provides an exact schematic diagram for the interface board and in a stepwise manner, leads the reader through the steps in software development. The circuit is used to detect the unauthorized opening of any of nine windows or four·doors and sounds an alarm if this occurs. Having followed the directions provided, I now have a very useful security system for less than $30.00. Control of an AC load is also treated. A complete discussion of line isolation and the use of solid state relays {opto-isolators and opto-couplers) is presented prior to the actual design of a circuit to control a lamp.
The last three chapters offer a tutorial in the construction and use of analog/digital, digital/analog converters and transducers. The AD 570 and AD 558 integrated circuits are used for these purposes. The interface that results from this project is a complete eight bit A/D-D/A conversion board having unlimited potential. The author carefully takes the reader through the construction, programming and use of the board as an electronic thermometer and also a device controller. It cost me under $45.00. to build the board. This is considerably less than comparable commercial units.
The treatment of each topic is well documented and illustrated with many examples. The use of flow charts to examine the construction of BASIC programs enhances the reader's understanding of the program's function and operation·. Some limited knowledge of electronics is assumed. Fundamental interpretation of schematic figures and assembly techniques are not illustrated. I did not find this a particular problem as the information is available from other sources. The schematic diagrams and the presence of data specification sheets enable the reader to modify the projects to fit specific needs. While it is possible to gain some insight and understanding without the CMS I/O card, it is an advantage to use 1t. The reader must wait for the card to arrive once ordered, thereby postponing use of the book. Programs to display data to a graphic screen were missing. Considering the popularity of graphics, this omission is unusual.
These minor objections do not detract from an excellent resource for newcomers to interfacing. Each topic considered also includes ideas for expansion and modification I have found several interesting applications for the security program and dozens of uses 1n the laboratory for the A/D-D/A board. This book certainly belongs on the shelf of anyone interested in computer interfacing and computer control.
NOTE: This review concerns The Apple Connection. There are similar titles organized and arranged along the same lines as the volume reviewed here which provide data· for the VIC-20 and IBM PC.
*Central Community High School
Route 50 West
Breese, IL 62230
Date:
09/26/85 to 09/29/85
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