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:
Jun. 06, 1995
Filed:
Aug. 12, 1991
Applicant:
Inventor:
Jeffrey W Porter, Austin, TX (US);
Assignee:
Dell USA, L.P., Austin, TX (US);
Attorneys:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G06F / ; G06F / ;
U.S. Cl.
CPC ...
395275 ; 364D / ; 36492792 ; 36492795 ;
Abstract
A parallel port adapter, which provides a special buffering circuit on the four control lines from the system to the printer. This circuit provides a low-impedance bidirectional path for communication between the CPU and the printer, whenever any of the control lines is active. The circuit uses blocking diodes on all four lines, and uses pass transistors in parallel with the blocking diodes, and uses power-robbing to turn on the pass transistors whenever the port is in use.