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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4.1 ★★★★★
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eave4sean
Los Angeles, US
★★★★★ 3
Really wanted this toy to be better...
Size: 10.5 inch Rubber Flex Tread
I got this toy because I have 3 large dogs that all like to pull things. I can't always play with them even though they follow me everywhere wanting to play, so I saw this toy and thought it would be good because it would give them something they can tug away at with each other. I saw the thick rubber and thought it would last awhile, but I was wrong. My German Shepherd and Pyrenees mix chewed though the first tire rather quick, and before I realized, I was finding chunks of tire around the house and yard. Thankfully, none of them tried to eat it. It seems like it could be a good toy for an aggressive chewer IF they are smaller and not as strong as these large dogs are, but it did not hold up long to mine.
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Reviewed in the United States on November 23, 2024
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kristine albrecht
New York, US
★★★★★ 5
Great and entertaining dog toy
Color: 4 Color For XS/S 2.2", Size: Small
These are probably my dog’s favorite toys currently. He loves the squeaking and they function well as a ball for fetching as well.
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Reviewed in the United States on May 28, 2026
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kathy w.
Natrona Heights, US
★★★★★ 5
Husky loves them
Color: 4 Colors For M/L 3.1", Size: Large
good size and nice quality
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Reviewed in the United States on May 26, 2026
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tom gordan
Natrona Heights, US
★★★★★ 5
Our dog loved these?!!
Color: 4 Color For XS/S 2.2", Size: Small
We have a miniature long haired Dachshund named Winston and OMG HE ABSOLUTELY LOVES THESE squeaky toys. I swear he must have played with them for 6 hours straight the first time we gave it to him. He love it so much that he even took it to bed with him that 1st night. Many months later these are still his favorite toys. I think he likes the saucer-like shape of them & how they fit & feel in his mouth. The squeakers don't last very long but that's always been the case with squeaky toys & it doesn't seem to bother Winston much either.
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Reviewed in the United States on May 19, 2026
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Barbs
Dallas, US
★★★★★ 5
My dog loves these
Color: 4 Colors For M/L 3.1", Size: Large
My dog absolutely goes crazy over these squeaky toys. They bounce all directions and he can entertain himself for a bit til I'm free. However, if your are trying to talk on phone or with family you might want to hide them for a while. Noisy. Lol
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Reviewed in the United States on May 21, 2026

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