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:
Dec. 16, 1997
Filed:
Nov. 18, 1994
Abbas Khashayar, Anaheim, CA (US);
Alps Electric (USA), Inc., San Jose, CA (US);
Abstract
An IBM PC compatible keyboard is provided which, on power-up, does not access the keyboard LEDs until receiving a command from the host computer. When the keyboard controller performs a Basic Assurance Test (BAT) on power-up before receiving a host command, the controller does not turn on the LEDs. Upon receiving a Reset command from the host, the controller: (1) turns on the LEDs and performs a BAT with LEDs on; and (2) flashes the LEDs a second time to be compatible with the IBM PCs. Another feature of the invention is a non-destructive test of the controller RAM during BATs. The RAM is tested non-destructively both for the 'stuck-at-1' and the 'stuck-at-0' conditions. Still another feature is that the controller determines the state of the keyboard LEDs without reading a hardware port. The controller keeps track of the LED state by flags in the controller memory, and the controller determines the LED state by reading the flags.