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Browse Prior Art Database

5»-Inch Diskette Interchange Architecture

IP.com Disclosure Number: IPCOM000042512D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 3 page(s) / 32K

Publishing Venue

IBM

Related People

Aiken, JA: AUTHOR [+3]

Abstract

This article describes a 5»-inch diskette standard adapted for data interchange which makes a system incorporating the diskette less sensitive to catastrophic data loss resulting from loss of a single sector on the diskette. A significant concern in word processing and small office computers is the interchange of diskettes. Currently, there is no 5»-inch diskette standard governing interchange architecture. Some personal computers use the 5»-inch diskettes, but data interchange is not required therein. The most nearly-applicable standard is the one which applies to 8-inch diskettes. Many of the concepts in the 8-inch diskette standard are applicable in general. Others, particularly track layouts and recording techniques, are aimed specifically at 8-inch diskettes.

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5»-Inch Diskette Interchange Architecture

This article describes a 5»-inch diskette standard adapted for data interchange which makes a system incorporating the diskette less sensitive to catastrophic data loss resulting from loss of a single sector on the diskette. A significant concern in word processing and small office computers is the interchange of diskettes. Currently, there is no 5»-inch diskette standard governing interchange architecture. Some personal computers use the 5»-inch diskettes, but data interchange is not required therein. The most nearly-applicable standard is the one which applies to 8-inch diskettes. Many of the concepts in the 8-inch diskette standard are applicable in general. Others, particularly track layouts and recording techniques, are aimed specifically at 8-inch diskettes. The present solution to the interchange question attempts to utilize the applicable concepts while making maximum use of the storage on the 5»-inch diskette. Programs on the involved system are loaded from diskette using instructions stored in read- only storage (ROS). The ROS programs must have a predefined starting point for all program load operations for all supported applications (emulation, word processing, etc.). In order to make use of available space on the 5»-inch diskette, all sectors on the diskette are formatted to 512-bytes per sector using Modified Frequency Modulation (MFM) recording technique. Because there are no existing systems with which the involved system must interchange diskettes, smaller sector sizes and Frequency Modulation (FM) recording on certain tracks or cylinders are not required. Similar to the 8-inch diskette standard reserving Track 0 for diskette labels, the present architecture reserves the first sector on the diskette for interchange information. With 512 bytes per sector, a single sector can contain sufficient interchange information. Therefore, reserving an entire track is not necessary, and the rest of the first track is available for use by the system. For the purpose of recovering from volume read errors, an additional sector is allocated for a duplicate copy of the interchange information. This sector...