Browse Prior Art Database

Use of Magnetic Printing for Word Processing and Audio Storage

IP.com Disclosure Number: IPCOM000089840D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 16K

Publishing Venue

IBM

Related People

Barrekette, ES: AUTHOR [+2]

Abstract

The office environment has many requirements for data storage in machine-readable form. At present, it is anticipated that many of these applications will be provided by conventional magnetic storage, such as cards, floppy disks, audio disks or cassettes. In some cases, magnetic bubbles may be an alternative.

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Use of Magnetic Printing for Word Processing and Audio Storage

The office environment has many requirements for data storage in machine- readable form. At present, it is anticipated that many of these applications will be provided by conventional magnetic storage, such as cards, floppy disks, audio disks or cassettes. In some cases, magnetic bubbles may be an alternative.

We show here that in many cases the provision of data in machine-readable form can be provided by printing the information with a magnetic ink, and later reading it out with conventional magnetic reading technology.

In order to assess the potential role of this type of data recording, one must get an understanding of the limits of the information recording density, the information writing rate, and the information reading rate. In the discussion that follows, it should be noted that many applications in the office require relatively small amounts of data (a typed page may have no more than about 6000 characters, for example), and much lower data rates than are encountered in data storage devices for conventional digital computers.

The easiest way to treat the problem of information density is to simply assume one is printing with a single vertical bar mounted on a high speed hammer, which is transported by a carrier with positional accuracy comparable to that in a matrix printer. Such a printer can print 60 dots per inch, some 20 mils in diameter. If we assume the bars are 0.1'' high, and that the carrier motion is sufficiently uniform that we need not worry about two transitions per bit, then we can print (or not print) 60 bars per inch, each 0.1'' high by, say, 0.01'' wide. Thus, the area per bit is 2x10/-3/ square inches. Hence, a standard 8.5'' by 11'' sheet of paper could hold a maximum of 47,000 bits. Assuming a 128-character set, this is equivalent to 6000 characters (which is the maximum number of characters one ordinarily can print on a page).

The number calculated in the above example is a lower bound. If we, for example, were to take advantage of the quality factor of the SELECTRIC* typewriter, then one can print lines of the order of 0.002'' wide. Assuming the carrier has comparable positional certainty -- as should be readily feasible with stepper motors or optical emitters - then the capacity of a page is increased to 30,000 characters. Alternatively, one could store the entire 6000 characters in a band about two inches high -- or a piece of paper approximately the size of a magnetic card.

A reasonable upper bound for low cost magnetic printing would be 1500 bars per inch, which can be achieved with classical, conventional quality printing technology. In this case the total amount of information stored with bars 0.1'' high would be approximately 1.25 Mbits. Note that the bar height is just another name, in magnetic recording, for track width. If one accepts a higher cost reading head, one should be able to read at a density of over 100 tracks per in...