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Diskette Characteristics Recognition Algorithm

IP.com Disclosure Number: IPCOM000035243D
Original Publication Date: 1989-Jun-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 14K

Publishing Venue

IBM

Related People

Davis, KD: AUTHOR [+3]

Abstract

The Diskette Characteristics Recognition Algorithm determines diskette types by comparing physical states and recorded data; progressively narrowing the states and data to known combinations of diskette characteristics. This algorithm recognizes four unique formats: IBM 8- inch diskettes, ISO 8-inch diskettes, PC DOS type 5.25-inch diskettes and an 8-inch Emulated format for High Density 5.25-inch diskettes.

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Diskette Characteristics Recognition Algorithm

The Diskette Characteristics Recognition Algorithm determines diskette types by comparing physical states and recorded data; progressively narrowing the states and data to known combinations of diskette characteristics. This algorithm recognizes four unique formats: IBM 8- inch diskettes, ISO 8-inch diskettes, PC DOS type 5.25-inch diskettes and an 8-inch Emulated format for High Density 5.25-inch diskettes.

The following is a list of the characteristics to be compiled by this algorithm. - The diskette size: 5.25 or 8 inch. - The diskette track density: 48 or 96 tracks per inch. - The recording mode: FM or MFM. - The number of diskette sides: 1 or 2 sided. - The number of tracks per side: 40, 77, or 80. - The number of sectors per track: 8, 15, or 26. - The data sector length: 128, 256, 512, or 1024 bytes. - The label format: IBM 8-inch, ISO, PC DOS or unsupported. - The character format is ASCII or EBCDIC.

The relevant diskette characteristics which distinguish one diskette from another are as follows: - The diskette size (8 or 5.25-inch) initiated by hardware. - Track 0 of 8-inch diskettes are always written as 128 byte records, FM recording format, at a rate of 250 K bits per second at 360 revolutions per minute. - IBM 8- inch, ISO 8-inch, and 8-inch emulated 5.25-inch diskettes all contain a Volume Label on track 0 sector 7. The volume label field 'Label Identifier' identifies the Character type (ASCII or EBCDIC) and confirms the presence of the Volume label. The 'Label Standard' field identifies the recording standard (ISO or IBM). The 'Physical Record Length of Available Space' field identifies the record length of the Diskette Data area (128, 256, 512, 1024 byte sectors). The 'Volume Surface Indicator' field identifies the number of diskette sides (1 or 2) and the recording format of the diskette (FM or MFM). The 'Label Extension Indicator' field identifies the number of extra cylinders (beyond cylinder 0) which are used for the label area. - The 8-inch emulated format 5.25-inch diskettes have a track 0 written as 256 bytes records, MFM recording, at a rate of 500 K bits per second at 360 rpm. - PC DOS type diskettes are defined in 5 different formats. All formats have a data record size of 512 byte sectors written in MFM. - At 2/15 - specifies a high density diskette with two sides and fifteen sectors per track. It is written at a data rate of 500 K b/s at 360 rpm. - PC 2/9 - specifies a low density diskette with two sides and nine sectors per t...