Loading patent…
AssigneeThe Solartron Electronic Group Limited
InventorsHoward Anthony Dorey, Robert John Cooke
Estimating the term…
An interface circuit for use in a data transmission system is designed to be used not only between a highway and a device but also to link highways and can be commanded to enter a status in which commands sent to it on one highway are modified and sent out as commands on a second highway so that a controller device on the one highway can control devices not only on that highway but also on the second highway, with extension, if desired, to a third highway or beyond. To achieve this, the interface circuit has two ports each for connection to a respective one of two substantially identical highways, and status control means responsive to signals received at either port to establish different statuses of the interface. For inter-highway communication, the status control means is responsive to a command signal of particular form at either port to produce a modified command signal at the other port.
An interface comprising two symmetrical ports connectable to data highways, each of said ports including data terminals, handshake terminals, at least one control terminal to which can be applied a special command signal indicative of whether a data byte on said data terminals is information or a command, and status control means responsive to command bytes accompanied by said special command signal received from a data highway at either port to establish different statuses of the interface, including statuses in which the data terminals of the ports are placed in communication for the flow of data therebetween;
An interface comprising two symmetrical ports connectable to data highways, each of which includes data terminals, handshake terminals, at least one control terminal to which can be applied a special command signal indicative of whether a data byte on said data terminals is information or a command, and status control means responsive to command bytes accompanied by said special command signal received from a data highway at either port to establish different statuses of the interface, including statuses in which the data terminals of the ports are placed in communication for the flow of data therebetween;
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
No related US applications are recorded in the indexed filing history.
Coupling between buses: using bus bridges
Using bus bridges: with address mapping
Being a system bus, e.g. VME bus, Futurebus, Multibus: with asynchronous protocol
Computing and data processing
Term ended 6 Sep 1994 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
U.S. Ser. No. 570,688, filed 28th Apr. 1975, claiming priority from British application 19155/74 dated 1st May 1974.
The present invention relates to interfaces for data transmission systems, of the type which comprise a plurality of devices linked by a highway via the interfaces. Devices include data acceptors, which are primarily addressed as listeners, although they may be addressed as talkers in poll and other command operations; data sources, which are primarily addressed as talkers but are also addressable as listeners during command operations; devices which are both sources and acceptors; and controllers which act as talkers and listeners in establishing the operational status of the overall system. A controller is generally also a data source and a data acceptor, and may be a device generally referred to as a data processor or a digital computer.
In operation a controller sets up a status in which one device is a talker and one or more devices are listeners. Data is then transferred from the talker to the listener(s). A system may include more than one controller but only one such device can exercise control at a time.
The invention will now be described in more detail, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a simplified schematic block diagram of an interface embodying the invention;
FIG. 2 shows a data transfer system composed of two sub-systems linked by the interface;
In order not to encumber the disclosure unnecessarily, no detailed description will be given of the constituent circuits of the interface. These are arranged to perform the described functions in ways which are well known in themselves. The invention is not concerned with the handshake process and the terminals therefor are not described. It is assumed that each port has its handshake terminals and handshakes on its side of the interface in a manner generally known per se and specifically as described in the aforementioned Patent Application, for example.
Table I below sets out the meaning of data bytes which are interpreted as commands (being accompanied by ATN true). It is assumed that a 7-bit code with bits b.sub.1 to b.sub.7 is employed, plus a parity bit b.sub.8 which will be ignored in what follows. Data bytes with ATN false have the usual ISO-7 bit code meaning, e.g. as set out in the aforementioned draft.
TABLE 1 ______________________________________ BITS COMMAND b.sub.7 b.sub.6 b.sub.5 b.sub.4 -b.sub.1 TYPE NOTATION ______________________________________ 0 0 0 All values Addressed Commands 0.0 to 0.15 0 0 1 All values Universal Commands 1.0 to 1.15 0 1 0 All values Intermediate Listen 2.0 to 2.15 Addresses 0 1 1 0000 to Terminal Listen 3.0 to 3.14 1110 Addresses 0 1 1 1111 Unlisten 3.15 1 0 0 All values Intermediate Talk 4.0 to 4.15 Addresses 1 0 1 0000 to Terminal Talk 5.0 to 5.14 1110 Addresses 1 0 1 1111 Untalk 5.15 1 1 0 All values Secondary Commands, 6.0 to 6.15 Group 1 1 1 1 All values Secondary Commands, 7.0 to 7.15 Group 2 ______________________________________