Asynchronous, hierarchical loop communication system with independent local station control of access to inbound time portions without central control
US4028667A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 22, 1975 |
| Grant date | Jun 7, 1977 |
| Priority date | — |
| Expiry date | Dec 22, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L12/4637
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A CPU communicates via an indirect memory access channel (IMA) to many devices on a high speed loop and an asynchronous low speed loop. The IMA connects to a loop adaptor (LAD) which connects to the primary parallel loop. A low speed serial loop is coupled to the primary loop through a general device adaptor and another LAD. The time of the loops is broken down into frames divided into inbound and outbound halves. Each half frame carries address and control data. The address in each frame is highly variable depending upon demand by devices and the allocation of service is controlled by interrupt signals by devices on the loops which can demand service whenever an empty or free inbound frame passes by their inputs as indicated by signals known as free bit signals, which are suppressed as soon as a device seizes a free inbound frame.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.