PC-DOS 360K format - Revision history

SJK at 10:30, 5 September 2024

2024-09-05T10:30:14Z

Dan Tobias at 20:47, 8 September 2019

2019-09-08T20:47:29Z

Jsummers: Category:MS-DOS

2017-03-29T16:29:58Z

Category:MS-DOS

Dan Tobias at 23:34, 27 March 2014

2014-03-27T23:34:28Z

Dan Tobias: /* Links */

2014-03-11T22:04:24Z

‎Links

Dan Tobias at 09:08, 15 February 2014

2014-02-15T09:08:51Z

Dan Tobias at 03:34, 4 October 2013

2013-10-04T03:34:33Z

Dan Tobias at 00:00, 10 May 2013

2013-05-10T00:00:07Z

Dan Tobias at 03:36, 7 May 2013

2013-05-07T03:36:29Z

Dan Tobias at 03:03, 6 May 2013

2013-05-06T03:03:40Z

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-The '''PC-DOS 360K format''' was a very common floppy disk format in the 1980s, used on IBM PCs and compatibles. It replaced earlier [[PC-DOS 160K format|160K]], [[PC-DOS 180K format|180K]], and [[PC-DOS 320K format|320K]] formats using either fewer sectors, single-sided disks, or both, with a new format getting the most out of a double-sided, double-density 5 1/4" floppy disk. It had 40 tracks per side, with 9 sectors per track, and 512 bytes per sector. Data was stored with [[MFM encoding]]. The disk turned at 300 RPM.
+The '''PC-DOS 360K format''' was a very common floppy disk format in the 1980s, used on IBM PCs and compatibles. It replaced earlier [[PC-DOS 160K format|160K]], [[PC-DOS 180K format|180K]], and [[PC-DOS 320K format|320K]] formats using either fewer sectors, single-sided disks, or both, with a new format getting the most out of a double-sided, double-density 5 1/4" floppy disk. It had 40 tracks per side, with 9 sectors per track, and 512 bytes per sector. The disk turned at 300 RPM.
-These disks were generally used with [[FAT12]] file systems under the MS-DOS or PC-DOS operating system.
+These disks were generally used with [[FAT12]] file systems under the MS-DOS or PC-DOS operating system, but (far more rarely) were used with other filesystems too (e.g CP/M-86). The sector headers, etc, were based on [[IBM 3740]] format, albeit with [[MFM encoding]] (double density) replacing the original [[FM encoding]] (single density).
 After being a commonplace format for most of the 1980s, this format declined in favor of the high-density [[PC-DOS 1.2M format]] and the 3 1/2" [[PC-DOS 720K format]] and [[PC-DOS 1.44M format]]. (There were compatibility issues in reading 360K disks on low-density drives after they were written to with a high-density drive, even though the writing is done in an emulation of the old format, due to the different drive head on the newer drives. The high-density drive heads were smaller, and the data written by them might not be picked up correctly by the larger low-density heads, particularly if the new data was overwriting data stored earlier using large-headed drives, which might not be completely overwritten.)

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 The '''PC-DOS 360K format''' was a very common floppy disk format in the 1980s, used on IBM PCs and compatibles. It replaced earlier [[PC-DOS 160K format|160K]], [[PC-DOS 180K format|180K]], and [[PC-DOS 320K format|320K]] formats using either fewer sectors, single-sided disks, or both, with a new format getting the most out of a double-sided, double-density 5 1/4" floppy disk. It had 40 tracks per side, with 9 sectors per track, and 512 bytes per sector. Data was stored with [[MFM encoding]]. The disk turned at 300 RPM.

← Older revision		Revision as of 16:29, 29 March 2017
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	[[Category:IBM]]		[[Category:IBM]]
	[[Category:Microsoft]]		[[Category:Microsoft]]
		+	[[Category:MS-DOS]]

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 * [http://www.textfiles.com/programming/FORMATS/formats.pro Info on MS-DOS 1.x - 2.x disk formats]
 * [http://67.185.176.54:8080/diskette_handling.html Working with old diskettes]
 [[Category:IBM]]
 [[Category:Microsoft]]

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 == Links ==
 * [http://www.textfiles.com/programming/FORMATS/formats.pro Info on MS-DOS 1.x - 2.x disk formats]
 [[Category:IBM]]
 [[Category:Microsoft]]

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 These disks were generally used with [[FAT12]] file systems under the MS-DOS or PC-DOS operating system.
-After being a commonplace format for most of the 1980s, this format declined in favor of the high-density [[PC-DOS 1.2M format]] and the 3 1/2" [[PC-DOS 720K format]] and [[PC-DOS 1.44M format]]. (There can be compatibility issues in reading 360K disks on low-density drives after they were written to with a high-density drive, even though the writing is done in an emulation of the old format, due to the different drive head on the newer drives.)
+After being a commonplace format for most of the 1980s, this format declined in favor of the high-density [[PC-DOS 1.2M format]] and the 3 1/2" [[PC-DOS 720K format]] and [[PC-DOS 1.44M format]]. (There were compatibility issues in reading 360K disks on low-density drives after they were written to with a high-density drive, even though the writing is done in an emulation of the old format, due to the different drive head on the newer drives. The high-density drive heads were smaller, and the data written by them might not be picked up correctly by the larger low-density heads, particularly if the new data was overwriting data stored earlier using large-headed drives, which might not be completely overwritten.)
 In the late '80s and early '90s, it was common for desktop PCs to have both 5 1/4" and 3 1/2" disk drives in order to be compatible with all software and data, which might be distributed on either format. Often the 5 1/4" drive was drive A, and the 3 1/2" one was drive B. Later PCs, however, were more likely to have only a 3 1/2" drive, set up to respond to both drive letters. Eventually, PCs stopped having floppy disk drives altogether as other data storage and transfer media took over.