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:
Aug. 27, 1991
Filed:
Mar. 30, 1990
David M Lewis, Santa Cruz, CA (US);
Seagate Technology, Inc., Scotts Valley, CA (US);
Abstract
A programmable register stores a control bit for settting the logic polarity of an I/O signal at an I/O terminal of an integrated circuit. The I/O polarity control signal is combined in an exclusive-OR logic circuit with the I/O signal to provide a given logic polarity for the I/O signal. For a bi-directional I/O terminal, two exclusive-OR gates are used, one for controlling polarity of output signals from the integrated circuit to the I/O terminal and the other for controlling the polarity of input signals to the integrated circuits which are received at the I/O terminal. The control of the I/O signal polarity is particularly useful for a disk-drive controller which interfaces with different magnetic disk drive units, having different I/O signal polarity requirements.