The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 07, 1981
Filed:
Nov. 29, 1979
S Barry McClelland, Woodland Hills, CA (US);
Micropolis Corporation, Canoga Park, CA (US);
Abstract
A magnetic recording system is provided which encodes four bits of an eight bit 'byte' at a time, and is thus compatible with most general purpose data processing systems which process eight bit bytes. Also, the special magnetic recording code groups which are formed have at least two '0's' between each '1', and always include at least one '1' in each code group, thereby increasing the average frequency of magnetic transitions and reducing the requirements for the phase lock oscillator timing circuit compared to previous methods. In addition, the conversion circuitry for converting from the short data groups to the longer code groups is simplified by the use of a small 'Programmable read Only Memory' or 'PROM' and 'EXCLUSIVE-OR' circuit logic to insure proper code bit groupings of '1's' and '0's' within each code group and at the transitions between code groups. Similar simplifications are accomplished in the implementation of the 'Read' decoding logic; and the shift registers for buffering to the 'Read' and 'Write' Programmable Read-Only Memories, are shared, thereby minimizing the expense of the required serial-to-parallel conversion and returning the PROM parallel output to serial form.