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Apple ProDOS:  Advanced Features for Programmers, a Review.....
                                               .....Bill Morgan

Gary Little, the prolific author of Inside the Apple //e and Inside the Apple //c, has yet another new book out.  This one is called Apple ProDOS:  Advanced Features for Programmers.  In this volume Little covers just about all you need to know to write assembly language programs under ProDOS, from simply passing commands to BASIC.SYSTEM, through great detail on all the MLI calls, to writing your own interrupt handlers and device drivers.

Here's a quick summary of the book's contents:

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1 - An Introduction to ProDOS -- Little starts out with the history of Apple's DOS's, a comparison of ProDOS and DOS 3.3, and a summary of important features of ProDOS.

2 - Files and File Management -- Here he covers the directory structures, file structures, disk formatting, and gives us a READ.BLOCK program.

3 - Loading and Installing ProDOS -- This chapter goes into the boot process, ProDOS' memory usage, and the Global Page.

4 - The Machine Language Interface -- This is the information on using the MLI, its error codes, and complete details of all MLI calls.

5 - System Programming Featuring BASIC.SYSTEM -- Here we have a discussion of system programs, the structure and commands of BASIC.SYSTEM, and assembly language programming under BASIC.SYSTEM.

6 - Interrupts -- In this chapter Little covers interrupts in general, ProDOS interrupt handling, and programming the Apple mouse.

7 - Disk Drivers -- Nearing the end, we go into identifying and handling foreign disk drivers, driver commands, the /RAM driver, and adding your own driver.

8 - ProDOS Clock Drivers -- And finally we find out about using the built-in clock support, adding a clock driver, and reading the date and time from Applesoft.
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An important strength of this book is the wealth of examples.  In the chapter on the Machine Language Interface there is an example of the correct use of EVERY MLI call.  The BASIC.SYSTEM chapter includes an ONLINE command, to identify all disk volumes currently on line.  The chapter on interrupts contains a couple of examples of mouse programming.  The Disk driver section has a listing of a simple /RAM driver for main memory.  And this is just a sample of the useful code provided in Little's new book.  A companion disk containing all of the book's programs and more is available for $25.00 from the author.

I hear some of you asking:  How does Apple ProDOS:  Advanced Features (APAF) compare to Beneath Apple ProDOS (BAP)?  Well, the two books complement each other quite nicely.  With all its examples, treatment of interrupt handlers and device drivers, and overall clarity, I'd say that APAF is the better book on programming under ProDOS.  BAP has useful examples as well, and better detail about the internals of diskette formatting and how ProDOS works, especially with its 120+ page supplement describing the code on a line-by-line basis.  So if you're concerned with understanding the inner workings of the operating system, or with modifying its behavior, BAP is the book to have.  Otherwise, get APAF for the best information on programming using ProDOS.  Personally, I'm glad to have both books on the shelf here, along with Apple's ProDOS Technical Reference Manual.

Apple ProDOS:  Advanced Features for Programmers, by Gary B. Little.  Brady Communications Co., 1985.  266+iv pp., Reference Card.  $17.95.  Available from S-C Software for $17 + shipping.
