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:
Aug. 02, 1994
Filed:
Jul. 18, 1991
Stanley E Cox, Farmers Branch, TX (US);
Mark E Ish, Harris County, TX (US);
Texas Microsystems, Inc., Houston, TX (US);
Abstract
An expansion system for a bus-architecture system is disclosed, particularly for an SBus-compatible system. The expansion system includes a host expansion board which fits into one of the expansion slots connected to the SBus, a cable connected to the host expansion board, and an expansion chassis connected to the cable. A memory management unit is included in the host expansion board, for mapping physical addresses on said SBus into addresses of add-on functions installed in the expansion chassis. This mapping allows for varying memory size functions to be installed into a single expansion slot. The MMU also copies the ID PROMs from each of the add-on functions into RAM on the host expansion board, so that such expansion is transparent to the driver software. Latches and control functions are also provided so that one of the add-on functions can be the SBus DMA master within the timing specifications; this is enabled by initiating the DMA cycle early in the expansion chassis, and by latching the communicated states. The data and acknowledge signals can be synchronized with SBus, and succeeding data can be pipelined so that burst write DMA operations can be performed.