Patent Yard Sign in
Expired Canadian patentCanada

Variable length packet switching system

CA 1250648 A · Owner: American Telephone And Telegraph Company · Inventors: Hasley, Lloyd A.

CIPO record

Overview

Drawings and full text

Its claims, description and drawings are in the Canadian Patents Database.

Open the CIPO record

Abstract From the Canadian patent

Abstract, A packet switching system is disclosed for transmitting variable length packets between system ports. Each byte of each packet has a special one-bit field for indicating whether the byte is the last byte of a packet. A "1" in this field specifies that the byte is the last byte of a packet and activates port control circuitry that changes the potential on a system control conductor to indicate that the system data bus is now idle and free for use by other ports.

Read the whole patent

Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.

Why it's free to use

  • Granted February 28, 1989. A Canadian patent filed before October 1, 1989 lasted 17 years from grant, so its term ended February 28, 2006.
  • We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
FiledNovember 12, 1985
GrantedFebruary 28, 1989
Term endedFebruary 28, 2006
Patent numberCA 1250648 A
Classification (IPC)H04Q3/42 +2 more

Timeline

Timeline From CIPO dates

1986198919921995199820012004Application filedNov 12, 1985Patent grantedFeb 28, 1989Term endedFeb 28, 2006

Sources & verification

Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.