Microcomputer with on-board chip selects and programmable bus stretching
US5151986A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 27, 1987 |
| Grant date | Sep 29, 1992 |
| Priority date | — |
| Expiry date | Aug 27, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F13/4243
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
A microcomputer with an external bus interface for providing communication with external peripheral devices such as memory and the like is provided with on-board chip select logic and programmable bus stretching capability. The chip select logic provides chip select signals to external devices when addresses fall within pre-selected ranges, eliminating the "glue" logic normally required for this purpose. The programmable bus stretching feature inserts a pre-selected number of "wait states" into any external bus cycle for which it is programmed by stretching, or freezing, the central processing unit and external bus interface unit clocks. Other internal clocks, such as those which drive timers and/or serial interface baud rate generators are not frozen by the bus stretch.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.