Organization of computer systems: the fixed plus variable structure computer
IRE-AIEE-ACM '60 (Western) Papers presented at the May 3-5, 1960, western joint IRE-AIEE-ACM computer conference
A functional description of macromodules
AFIPS '67 (Spring) Proceedings of the April 18-20, 1967, spring joint computer conference
Towards a Theory of Universal Speed-Independent Modules
IEEE Transactions on Computers
Modular Asynchronous Control Design
IEEE Transactions on Computers
A Theory of Asynchronous Control Networks
IEEE Transactions on Computers
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The feasibility and the problems associated with the design of asynchronous digital systems have been variously studied and reported. J. B. Dennis has characterized modular design of asynchronous digital systems in the following manner: The structure of an asynchronous digital system may be divided into the data flow structure and the control structure. The storage of data, the flow of data and the operations performed on them take place in the data flow structure. The different operations taking place concurrently in the data flow structure are co-ordinated by the control structure. Each operational unit of the data-flow structure has, in addition to data links (data input lines), a control link connecting it to some part of the control structure. A control link consists of two wires called the ready line and the acknowledge line. To cause an operator to operate on an input, the input is made available to it (the operator) on the input data link and a ready signal is sent to it (the operator) on the ready line of the control link. After the operation has been performed on the output placed on the output data link the operator returns an acknowledge signal on the acknowledge line. The time difference between the arrival of the ready signal and the return of the acknowledge signal is arbitrary and may depend on the operator, the input, and can even be random so long as the acknowledge signal correctly implies completion of the operation. The control structure consists of control modules interconnected among themselves and to the dataflow structure through control links. Signals propagate in the forward direction on the ready line. The direction of a control link is the direction in which the signals propagate on its ready line. In addition to control links a control module can have conditional inputs and outputs. The conditional inputs convey information about the condition of some operation or control modules to this module (and thereby affect the operation of the module), and the conditional outputs convey the condition of this module to other circuits.