DOS 4.1 Disk Operating System Second Edition
SKU: 90829067784

DOS 4.1 Disk Operating System Second Edition

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Description

DOS 4.1 Disk Operating System Second EditionDOS 4. 1 is a newly imagined Disk Operating System for the Apple ][ computer, initially released in 2018. When the DOS 4. 1 Manual was published, DOS 4. 1 was not yet finished until Build 46 was completed in 2019. Designed and programmed by Walland Philip Vrbancic, Jr., a professional programmer and Electrical Engineer since 1983, DOS 4. 1 contains the power and the flexibility he always thought DOS should have while remaining essentially compatible

DOS 4.1 is a newly imagined Disk Operating System for the Apple ][ computer, initially released in 2018. When the DOS 4.1 Manual was published, DOS 4.1 was not yet finished until Build 46 was completed in 2019. Designed and programmed by Walland Philip Vrbancic, Jr., a professional programmer and Electrical Engineer since 1983, DOS 4.1 contains the power and the flexibility he always thought DOS should have while remaining essentially compatible with DOS 3.3. DOS 4.1 Disk Operating System Second Edition describes all of the features that comprise DOS 4.1L and DOS 4.1H, including those features introduced by Build 46, using redesigned Tables, Figures, Schematic Diagrams, and example Assembly Language Routines. The following list are some of the features that have been engineered into the second edition of the DOS 4.1 Disk Operating System. DOS 4.1H boots directly into Language Card memory and sets HIMEM to 0xBE00. All five of its file buffers are fully contained in Language Card memory. DOS 4.1 supports the full 65C02 instruction set and it can now be used in both the Lisa and the Big Mac assemblers. Sourceror and Big Mac both support all SWEET16 opcodes. The ROM image described in this book supports the 65C02, SWEET16, and GARBAGE based on BongersÕ algorithm. DOS 4.1 supports most Clock Cards which play an integral role in Volume and File timestamps. Volumes may be titled, numbered, and initialized to boot or to store files and data exclusively. Even track 0x00 is used to store files and data. Files are loaded into memory and saved using a page-accelerated algorithm. DOS 4.1 supports Applesoft CHAIN, File DIFF, File GREP, File LIST, File Undelete, Sector Display, Syntactical HELP (only in DOS 4.1H), and full lowercase command and argument input. DOS 4.1 has an expanded File Manager with additional Opcodes, and the Boot and Volume INIT functions utilize the same BOOTCFG Table. The Volume Catalog may use a minimum of a single sector and the CATALOG output may be terminated by pressing the ESC key at any time. DOS 4.1 uses the B keyword to implement the ÒFile Delete/File SaveÓ strategy for disk space conservation. DOS 4.1 can read DOS 3.3 Volumes, files, and data. DOS 4.1 can easily initialize Volumes with up to 48 tracks having either 16 or 32 sectors per track. All the source code and all the schematics can be requested through www.applecored.net.

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SKU: 90829067784

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Valerie Joan
Whiting, US
★★★★★ 5
Worth it
Style: Charming Squeaky Dog Toys
My dog loved every single toy. He got so excited with how many they were that he didn’t know which one to play with lol. Great price for many toys and good quality and material.
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Reviewed in the United States on May 5, 2026
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Amazon Customer
West Palm Beach, US
★★★★★ 5
My dogs love these toys!
Style: Charming Squeaky Dog Toys
My dogs (14 lb pug and a lab) love these toys! I give a couple to them here and there so the box lasts longer. The squeaker does go kind of fast and that’s a lot of the draw but it was a great price for all those cute little toys. They even threw in a few rolls of doggie waste bags. Great value! Will buy again.
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Reviewed in the United States on April 7, 2026
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Mindo
Grantham, US
★★★★★ 4
Great quality- small squeakers
Style: Charming Squeaky Dog Toys
They are fine but they could be better. They are super cute- lots of cute shapes. All are about the size of an adult fist. The squeaker in each on is roughly the size of a nickel. I guess I had envisioned a bigger squeaker so more of the toy squeaked. They are fine though. They seem well made, no tags sticking out or loose threads. My dog has killed the squeaker on 4 so far today, but that’s the point and the reason I bought them. Oh and they don’t smell weird!! I have bought some that smell like they’ve been in the cellar for years- these do not. So honestly my only complaint- and it’s just personal preference- is I wish the squeaker was larger.
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Reviewed in the United States on April 17, 2025
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Kateynn
Grantham, US
★★★★★ 5
Good for small dogs
Style: Charming Squeaky Dog Toys
My dog (20lb chihuahua-pug mix) adores these. She's a plush toy serial killer, so the toys don't last long in my house, but with their pricing they are an affordable choice for being sacrificed. If your dog is more gentle, I can forsee these toys holding up very well for long term play and cuddling.
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Reviewed in the United States on April 24, 2026
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Brenda
New York, US
★★★★★ 5
They are the perfect size for small dogs.
Style: Weather-Themed Squeaky Toys
My dogs are 7# and 15# and they LOVE these squeaky toys. They are the perfect size for small dogs.
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Reviewed in the United States on June 10, 2026

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