Data processing system having shared memory
US4491909A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 22, 1982 |
| Grant date | Jan 1, 1985 |
| Priority date | — |
| Expiry date | Feb 22, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F15/167
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a data processing system, data is transferred between a plurality of functional devices through a shared memory without the intervention of the processor. The data transfer is controlled by a Shared Memory Access Channel (SMAC) having a pointer table storing memory addresses to control shared memory accesses and by the functional devices using device addresses, pointer identifers, indicating the pointer to be used from the pointer table, and control codes. The control codes used in the transfer include a Post code (P code), an Available code (A code) and an End of Process Code (E code). The device, from which data is transferred, is referred to as the upstream device, and the device to which data is transferred is referred to as the downstream device. The P code tells the downstream device that the upstream device has written a predetermined amount of data into a shared buffer area in the memory. The A code tells the upstream device that space is available in the buffer area for writing data to be transferred to the downstream device. The E code tells the downstream device that the data transfer operation from the upstream device has been completed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.