Information transfer system wherein bidirectional transfer is effected utilizing unidirectional bus in conjunction with key depression signal line
US4374429A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 27, 1980 |
| Grant date | Feb 15, 1983 |
| Priority date | — |
| Expiry date | Jun 27, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0489
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An information transfer system is described that includes a central processing unit (CPU) interconnected with a peripheral device such as an operator console by an interface bus of finite capacity. Transfer of information in the system is normally in a preferred direction from the CPU to the console. Provision is made to transfer information concerning key depressions on the console from the console to the CPU without using the bus by utilizing a normally continuously operating counter in the CPU that provides a sequence of coded count signals representative of individual keys that are provided on the console and that may be depressed. A comparator in the console compares coded count signals from the CPU counter with coded signals from the console representative of actual key depressions and provides a stop signal to the CPU counter via a single control line when an equal compare of the CPU counter and console coded signals occurs. The stopped coded count condition of the counter represents the actual key depressed. The CPU can then interrogate the current coded count state of the counter in the CPU at a convenient time to determine the actual key depressed and confirm that it has …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.