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. 10, 1983
Filed:
Feb. 09, 1979
Robert C Miller, Braintree, MA (US);
John J Bradley, Framingham, MA (US);
Boyd E Darden, Concord, MA (US);
Ming T Miu, Chelmsford, MA (US);
Jian-Kuo Shen, Watertown, MA (US);
Theodore R Staplin, Jr, Chelmsford, MA (US);
Honeywell Information Systems Inc., Waltham, MA (US);
Abstract
In a data processing system which includes one or more common buses to which a plurality of input/output controllers are connected for the transfer of data, blocks of data may be transferred between main memory and an input/output controller (IOC) synchronously with operation of the central processor unit (CPU). Logic is provided for enabling one unit of data to be transferred during a Data Multiplex Control (DMC) data transfer operation in which the requesting IOC requests a DMC data transfer of the CPU and later provides the CPU with a channel number assigned to the requesting IOC. In order to allow a data entry operator inputting data via a peripheral device connected to an IOC the ability to correct errors, a backspace character is provided so that the operator can enter it to indicate to the system to ignore the preceding character. Logic is provided within the system to allow a DMC IOC to detect the output of a backspace character from the peripheral device connected to the IOC and to inform the CPU of the entry of the backspace character by a special (backspace) input/output interrupt. Further logic is provided within the CPU to adjust pointers to the main memory input buffer to effectively ignore the byte of data corresponding to the character preceding the backspace character. Still further logic is provided within the DMC IOC to prohibit the sending of special (backspace) input/output interrupts to the CPU if there are no bytes of data remaining in the input buffer.