Creation and usage of mutually exclusive messages

• US 7,707,621 B2
• Filed: 12/02/2003
• Issued: 04/27/2010
• Est. Priority Date: 12/02/2002
• Status: Expired due to Fees

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Walmsley, Simon Robert
• Primary Examiner(s): Zand; Kambiz
• Assistant Examiner(s): Powers; William S
• Application Number:
  US10/727,164
• Publication Number:
  US 20040221287A1
• Time in Patent Office: 2,338 Days
• Field of Search: 710/36, 726/2, 380/255
• US Class Current: 726/2
• CPC Class Codes: B41J 2/04505 aiming at correcting alignment
• CPC Class Codes: B41J 2/04508 aiming at correcting other parameters
• CPC Class Codes: B41J 2/0451 for detecting failure, e.g. clogging, malfunctioning actuator
• CPC Class Codes: B41J 2/04528 aiming at warming up the head
• CPC Class Codes: B41J 2/04541 Specific driving circuit
• CPC Class Codes: B41J 2/04543 Block driving
• CPC Class Codes: B41J 2/04563 detecting head temperature; Ink temperature
• CPC Class Codes: B41J 2/04573 Timing; Delays
• CPC Class Codes: B41J 2/04586 controlling heads of a type not covered by groups B41J2/04575 - B41J2/04585, or of an undefined type
• CPC Class Codes: B41J 2202/20 Modules
• CPC Class Codes: G06F 21/554 involving event detection and direct action
• CPC Class Codes: G06F 21/57 Certifying or maintaining trusted computer platforms, e.g. secure boots or power-downs, version controls, system software checks, secure updates or assessing vulnerabilities
• CPC Class Codes: G06F 21/575 Secure boot
• CPC Class Codes: G06F 21/64 Protecting data integrity, e.g. using checksums, certificates or signatures
• CPC Class Codes: G06F 21/71 to assure secure computing or processing of information
• CPC Class Codes: G06F 21/73 by creating or determining hardware identification, e.g. serial numbers
• CPC Class Codes: G06F 21/74 operating in dual or compartmented mode, i.e. at least one secure mode
• CPC Class Codes: G06F 21/78 to assure secure storage of data address-based protection against unauthorised use of memory G06F12/14; record carriers for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: H03K 5/1252 Suppression or limitation of noise or interference specially adapted for transmission systems H04B15/00, H04L25/08
• CPC Class Codes: H04N 1/405 Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
• CPC Class Codes: Y10S 707/99933 : Query processing, i.e. searching
• CPC Class Codes: Y10S 707/99939 : Privileged access
• CPC Class Codes: Y10T 29/49401 : Fluid pattern dispersing device making, e.g., ink jet

Abstract

A method of preventing a first action associated with a first message from being performed in a target entity, the method including the steps of: sending the first message to the target entity, the first message being configured to cause the entity to perform the first action and a second action; sending a second message to the target entity, the second message being configured to cause the entity to perform a third action; and wherein the entity is configured such that performance of the second action and the third action is mutually incompatible.

Claims

1. A method of attempting a write to a target entity having first and second security fields to cause the target entity to perform an action, the method including the steps of:

initializing the first security field with a first initial value and the second security field with a second initial value;

sending a first message to the target entity that is an integrated circuit, the first message being configured to cause the entity to perform the action and to adjust the first and second initial values in the first and second security fields by respective first and second amounts resulting in respective first and second adjusted values;

sending a second message to the target entity, the second message being configured to cause the entity to adjust the first and second initial values in the first and second security fields by respective third and fourth amounts resulting in respective third and fourth adjusted values;

wherein the security fields have write restrictions associated with them which prevent values in the security fields being adjusted;

in accordance with the first message, if the initial values have been adjusted in accordance with the second message; and

in accordance with the second message, if the initial values have been adjusted in accordance with the first message, and

wherein the action is only performed when the initial values in the security fields have been adjusted in accordance with the first message, and

the first and second adjusted values are different than the third and fourth adjusted values, respectively.

2. A method according to claim 1, wherein the write restrictions:

prevent the second write from being performed in the event that the first write was previously performed; and

prevent the first write from subsequently being performed in the event that the second write is performed.

3. A method according to claim 1, wherein the second write is sent in response to a notification that the first write was not successfully performed.

4. A method according to claim 1, wherein the second write is sent in response to a notification that the first write was not received.

5. A method according to claim 1, wherein the second write is sent after a predetermined time has elapsed after sending the first write without receiving confirmation of the first write being received or successfully performed.

6. A method according to claim 1, wherein the messages are sent by a second integrated circuit.

7. A method according to claim 6, wherein the second integrated circuit is a printer controller.

8. A method according to claim 7, wherein the first integrated circuit is installed in a cartridge that is releasably attachable to a printer in which the printer controller is installed, such that the messages can be sent via a communications link between the printer controller and cartridge.

9. A method according to claim 8, wherein the performance of the action causes writing of ink remaining data in a data field of the first integrated circuit as an indicator of ink remaining in the cartridge.