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. 25, 1993
Filed:
Feb. 07, 1989
Christopher C Wanner, Houston, TX (US);
Alan L Goodrum, Cypress, TX (US);
Paul R Culley, Cypress, TX (US);
Compaq Computer Corp., Houston, TX (US);
Abstract
A computer system which includes a direct memory access (DMA) controller which can provide a 32 bit memory address and yet can also provide 24 bit memory address operation to remain compatible with previous systems. The DMA controller also monitors system operation and if only 24 bit address operations are occurring under the control of an external bus master or the DMA controller, the DMA controller drives the top memory address byte provided to a cache memory controller to help insure cache coherency. Additionally, the DMA controller can provide optimal time transfers for word width transfer between an odd starting memory address and an even starting input/output port.