Browse Prior Art Database

Index Selection Logic

IP.com Disclosure Number: IPCOM000084673D
Original Publication Date: 1975-Dec-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 3 page(s) / 51K

Publishing Venue

IBM

Related People

Herald, RF: AUTHOR [+2]

Abstract

This logic circuit distinguishes between the diskettes a and b as seen in Figs. 2 and 3, which have sector apertures 19Y and 19Z in their jackets located at 25 degrees and 7 degrees with respect to vertical axes a' and b' of the diskettes a and b, respectively. The logic provides an uplevel and a downlevel for the diskettes a and b, respectively on IMEDIA line c and provides pulses on +INDEX line d for both of the diskettes, but provides no index pulses on line d if a diskette having both of the apertures 19Y and 19Z is used by mistake.

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Index Selection Logic

This logic circuit distinguishes between the diskettes a and b as seen in Figs. 2 and 3, which have sector apertures 19Y and 19Z in their jackets located at 25 degrees and 7 degrees with respect to vertical axes a' and b' of the diskettes a and b, respectively. The logic provides an uplevel and a downlevel for the diskettes a and b, respectively on IMEDIA line c and provides pulses on +INDEX line d for both of the diskettes, but provides no index pulses on line d if a diskette having both of the apertures 19Y and 19Z is used by mistake.

Diskettes a and b are of the type disclosed in U. S. Patent 3,665,658 and are used in connection with light sensors 15Y and 15Z, similar to the sensor 15 shown in the mentioned patent. The sector apertures 19Y and 19Z in the two diskettes a and b are similar to the sector aperture 19 shown in the patent. The sector apertures 19Y and 19Z are in the jackets of the diskettes a and b. The diskettes have magnetic disks 10 which are rotatably disposed therein, and have openings through them which register with the sector apertures 19Y and 19Z in the jackets of diskettes a and b as the disks rotate.

Light sensors 15Y and 15Z are held by the machine in which diskettes a and b are used so that sensors 15Y and 15Z register, respectively, with apertures 19Y and 19Z but do not register, respectively, with apertures 19Z and 19Y. Thus sensor 15Y or 15Z is provided with a light pulse as the disk 10 rotates depending on which diskette a or b, is used in the machine.

Logic blocks 21-36 are each NAND circuits. Blocks 21, 23, and 35 having single inputs function as inverters. Circuits 25 and 27 are so connected as to function as a latch A, and circuits 31 and 3...