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:
May. 16, 1978
Filed:
Dec. 30, 1976
Jerome J Twibell, Phoenix, AZ (US);
Victor Michael Griswold, Phoenix, AZ (US);
Jaime Calle, Glendale, AZ (US);
Honeywell Information Systems Inc., Waltham, MA (US);
Abstract
An input/output system includes a plurality of modules and a system interface unit having a plurality of ports, each of which connects to a different one of the modules. The plurality of modules includes at least one processor and one memory module. The system interface unit includes a timer unit and a priority network for processing processor interrupt requests on a priority basis. The priority network connects to a register for storing coded priority level signals to be assigned to the different types of interrupt requests. The register is conditioned to store a low priority level for timer interrupts. The timer unit includes a preset register, an interval counter and a rollover counter. At the completion of each time interval, the interval counter is loaded automatically from the preset register and counting is continued. Simultaneously, the interval counter conditions the rollover counter to store a count registering the total number of completed intervals counted. The processor responds to a timer interrupt request by a special command which can only selectively clear the rollover counter to ZEROS when the interval counter is not in the process of completing another interval.