Data transfer control apparatus
First Claim
1. A bit-parallel, byte-serial data transmission system comprising a data highway and first, second and third handshake lines, a plurality of more than two devices and a corresponding plurality of interfaces linking said devices to said data highway and to said handshake lines, said devices including at least one data source device and more than one data acceptor device, said interfaces including logic means operable to control the exchange of data between a source device and a plurality of acceptor devices, the first line carrying a two-level signal determined by said logic means of the interface of the source device and indicating whether or not validly acceptable data is available, the second line carrying a two-level signal determined by said logic means of the interfaces of the acceptor devices and indicating whether all or not all acceptor devices have seen data, the third line carrying a two-level signal determined by said logic means of the interfaces of the acceptor devices and indicating whether all or not all acceptor devices have accepted a byte of data, and wherein said logic means of the interfaces are constructed and arranged to establish the following handshake cycle of operations (1) to (6):
- 1. First line to data available level;
2. Second line to level for data seen by all acceptor devices;
3. Signal from interface of the source device commanding the interfaces of the acceptor devices to accept data;
4. Interfaces of acceptor devices accept data in response to (3);
5. Third line to level for data byte accepted by all acceptor devices;
6. Change data byte and re-set first line to data available level to recommence the cycle.
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Accused Products
Abstract
In a multi-device data transmission system with source and acceptor devices linked by a data highway and handshake lines, provision is made for automatically adjusting the delay of the handshake cycle to suit the highway length and other determinative factors. This is achieved in that the acceptors do not accept data until told so to do via one handshake line, whereas the source is only allowed to issue this command when it has been told via another handshake line that all acceptors have seen the data. The system determines its own delay in this way and automatically adapts the delay to whatever length of highway is employed, whether a fraction of a meter in a circuit board or several tens of meters in inter-rack wiring.
9 Citations
5 Claims
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1. A bit-parallel, byte-serial data transmission system comprising a data highway and first, second and third handshake lines, a plurality of more than two devices and a corresponding plurality of interfaces linking said devices to said data highway and to said handshake lines, said devices including at least one data source device and more than one data acceptor device, said interfaces including logic means operable to control the exchange of data between a source device and a plurality of acceptor devices, the first line carrying a two-level signal determined by said logic means of the interface of the source device and indicating whether or not validly acceptable data is available, the second line carrying a two-level signal determined by said logic means of the interfaces of the acceptor devices and indicating whether all or not all acceptor devices have seen data, the third line carrying a two-level signal determined by said logic means of the interfaces of the acceptor devices and indicating whether all or not all acceptor devices have accepted a byte of data, and wherein said logic means of the interfaces are constructed and arranged to establish the following handshake cycle of operations (1) to (6):
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1. First line to data available level; 2. Second line to level for data seen by all acceptor devices; 3. Signal from interface of the source device commanding the interfaces of the acceptor devices to accept data; 4. Interfaces of acceptor devices accept data in response to (3); 5. Third line to level for data byte accepted by all acceptor devices; 6. Change data byte and re-set first line to data available level to recommence the cycle. - View Dependent Claims (2, 3, 4, 5)
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Specification