
Seattle, Washington — February 1, 2019 — Apple Pugetsound Program Library Exchange (A.P.P.L.E.) and Walland Philip Vrbancic, Jr. are proud to announce his new DOS 4.1 Manual: Disk Operating System for the Apple II. This book is in print for the first time, features a newly-designed cover, and is over 240 pages.
DOS 4.1 is a reimagined Disk Operating System for the Apple II computer, released in 2018. Programmed by Walland Philip Vrbancic, Jr., a professional programmer since 1983. It contains the power and the flexibility that he always thought DOS should have, while remaining compatible with DOS 3.3.
Availability
The DOS 4.1 Manual: Disk Operating System for the Apple II is available through the A.P.P.L.E. bookstore with production and fulfillment by Lulu. Disk images for the programs are available on the Apps page and on Walland’s site.

Features
- Table of Contents – PDF
- View Walland’s original Build 46 book on his site.
- Rebuilt Zero Page, faster Variable Handling, expanded Catalog details, longer Volume Names, and an expanded File Manager.
- Complete support for Language Cards and popular Clock cards, more extensive Time Stamps, and additions for homebrew ROM modifications.
- Included tools have been enhanced specifically for DOS 4.1, including Big Mac, CFFA Volume Manager, Disk Window, GPLE, Sourceror, and others.
- New and enhanced commands along with lowercase support.
- Compatible with DOS 3.3.
- Supported by third party products including: Applesauce, Disk Browser, Microm8, and Virtual II with more coming soon.
Author
Walland Philip Vrbancic, Jr. has been a professional programmer for over 20 years, worked at Raytheon and also in the Space Shuttle Simulation Laboratory at Rockwell about five months before the launch of STS-1. He became fascinated with all aspects of his Apple II Plus computer. According to Vrbancic, Jr.:
“At Rockwell I was tasked with developing the Fortran programs that could be launched on a Microsoft Z80 peripheral slot card in an Apple II Plus that would provide him with these capabilities. I found an ingenious way to reduce the size of the three-dimensional rotational matrix in order to accelerate data processing and the mapping of those results to the screen.
I was becoming increasingly interested in high-speed graphics animation and the only way I would learn that technology was to work for Ken Williams at Sierra On-Line. I terminated my work on my Master’s degree, gave notice to Rockwell, packed my bags, and moved to Oakhurst, California. At Sierra I assisted a colleague in migrating ScreenWriter to the newly marketed Apple IIe, I wrote all the I/O routines and ICON drawing routines for HomeWord Speller, and I nearly finished Goofy’s Word Factory, a children’s game to teach English grammar. Williams had a license to display certain Disney characters on a computer screen per approval by Disney for visual likeness and color. I would have finished the product if the designer of the game (Williams’ brother) could have developed the third game feature in a timely fashion. He apparently could not do so before I secured a position at Hughes Aircraft Company back in Los Angeles. I stayed all of 18 months at Sierra and I did utilize Williams’ high-speed graphics animation algorithms in Goofy, which I had to redesign in order to include collision detection on a dithered background. No other computer game could detect collisions on a dithered background at that time. Williams was impressed, and it was really hard to impress Williams.
I have the time and the continuing curiosity to delve into Apple II DOS now, and I have the opportunity to create my own version of DOS that contains the power and the flexibility I always thought DOS ought to and could have. I call my version of Apple II DOS, DOS 4.1. And this is my 45th build of DOS 4.1 with more to come at www.applecored.net. What a ride I have been on! Why? To see what I could do for this wonderful machine and its magnificent architecture!”
Producers
Brian Wiser — Producer of books, films, games, and events, as well as an Apple consultant, historian and archivist. Designer, editor, and co-producer of dozens of books including: Nibble Viewpoints: Business Insights From The Computing Revolution, Cyber Jack: The Adventures of Robert Clardy and Synergistic Software, Synergistic Software: The Early Games, Graphically Speaking: Enhanced Edition, What’s Where in the Apple: Enhanced Edition, and The WOZPAK Special Edition – an important Apple II historical book with Steve Wozniak’s restored original, technical handwritten notes. Producer/Director of the documentary film “Done The Impossible: The Fans’ Tale of Firefly & Serenity“, his Browncoat Cruise convention with Firefly cast, and an extra in the movie “Serenity.” Co-producer of Beagle Bros and Applied Engineering websites, the retro iOS game Structris, and co-producer/writer for CallAPPLE.org and Call-A.P.P.L.E. magazine. Brian is also the author of The Etch-a-Sketch and Other Fun Programs.
Bill Martens — Apple historian and enthusiast, programmer, President of Apple Pugetsound Program Library Exchange (A.P.P.L.E.) and co-producer of Call-A.P.P.L.E. magazine, and books like: Cyber Jack, Synergistic Software: The Early Games, Nibble Viewpoints, The WOZPAK Special Edition, and What’s Where in the Apple: Enhanced Edition. Bill also co-produced and co-programmed the retro iOS game Structris. Bill is the author of ApPilot/W1, Beyond Quest, The Anatomy of an EAMON, and multiple EAMon adventure games. He is a systems engineer specializing in office infrastructures and has been programming since 1976. And he is the production editor for the A.P.P.L.E. website CallAPPLE.org, writes science fiction novels in his spare time, and is a retired semi-pro football player.
Publisher
Apple Pugetsound Program Library Exchange (A.P.P.L.E.) has been a global Apple user group since 1978, with membership peaking near 50,000 in 1985. Offering many services, A.P.P.L.E. is also a book publisher and game developer, and has produced dozens of new book titles since 2013 and over 100 Apple software titles.
A.P.P.L.E. published the The WOZPAK Special Edition – a detailed book containing Steve Wozniak’s restored handwritten notes and printouts about his Apple II computer, as well as forewords from Steve Wozniak and other Apple legends. They also publish books such as: Graphically Speaking: Enhanced Edition by Mark Pelczarski, Tome of Copy Protection, Cyber Jack: The Adventures of Robert Clardy and Synergistic Software, Synergistic Software: The Early Games, Nibble Viewpoints: Business Insights From the Computing Revolution by Mike Harvey, What’s Where in The Apple: Enhanced Edition, The Colossal Computer Cartoon Book: Enhanced Edition by David H. Ahl, A.P.P.L.E. 1978 and 1979 magazine Compendiums, and the retro iOS game Structris.
Press Information is available at: www.callapple.org/press