Susan M Stephens

US Patent:

55510515, Aug 27, 1996

Filed:

Sep 20, 1994

Appl. No.:

8/309379

Inventors:

Lee Silverthorn - Paradise Valley AZ
Curtis Cornils - Phoenix AZ
Mark L. Kirchner - Phoenix AZ
Susan D. Stephens - Chandler AZ
Parker E. Crouse - Chandler AZ

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

G06F 1500
G06F 1200
G06F 1312

US Classification:

395800

Abstract:

A computer (20) includes a hardware memory access enforcer (50) to insure that various independent programs (52, 54) operating on the computer (20) follow isolated processing rules. Each program has its own memory domain (56), which may extend across instruction, data, and I/O memory spaces (40, 42, 44). A system controller program (52) is a trusted process. The system controller (52) may access memory in the domain (56) of any application (54), and program flow may exit system controller (52) to any application (54). However, applications (54) cannot access memory outside of their own domains (56), and program flow may not exit applications (54) to enter other applications (54). Program flow may exit applications (54) to system controller (52) only if directed to an entry address (60). A tracking circuit (74) verifies that a microprocessor (22) actually executes entry instructions (94) located at the entry address (60).

US Patent:

52218856, Jun 22, 1993

Filed:

May 3, 1991

Appl. No.:

7/695061

Inventors:

Eduardo M. Molieri - Mesa AZ
Susan D. Stephens - Chandler AZ
Andrew W. Hardell - Seguin TX
David L. Barron - Scottsdale AZ

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

G05B 1940

US Classification:

318685

Abstract:

A low-power dual voltage drive circuit and method which includes controlling a stepper motor overdriven with a high voltage. The stepper motor drive circuit includes a high voltage supply for overdriving the stepper motor, a low voltage supply, and an overdrive switch mechanism connected between the high voltage supply means and the stepper motor input. The method includes repetitively triggering the overdrive switch in response to a control signal, overdriving the stepper motor with the high voltage, producing an overdrive current, sensing the overdrive current, producing an additional control signal when the overdrive current reaches a preset value, switching off the overdrive current in response to the second control signal, resetting the overdrive switch to enable the overdrive switch to again receive the first control signal, and driving the stepper motor with a nominal low voltage.