A Control Word Model for detecting conflicts between microprograms

ABSTRACT

The compilation and optimization of a microprogram for a computer with a horizontal control word format is highly machine dependent. The compilation phase involves the detection of parallelism in a sequence of source statements followed by a mapping into a sequence of microoperations. The optimization phase involves combining these microoperations to form microinstructions in an optimal manner. One of the important subprocesses of the optimization phase is determining whether or not two or more microoperations can be executed concurrently. This paper presents the Control Word Model for determining when two or more microoperations can be executed concurrently. The Control Word Model is a machine independent model of the semantics of the control words for microprogrammable computers. As will be demonstrated, the concurrency permitted is sometimes determined not simply by the hardware configuration of buses, register, memories, and ALUs but also by the format of the control word chosen by the designer. This observation has motivated the development of the Control Word Model.

REFERENCES

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INDEX TERMS

Primary Classification:
  B. Hardware
  B.1 CONTROL STRUCTURES AND MICROPROGRAMMING
      B.1.4 Microprogram Design Aids

Additional Classification:
  B. Hardware
  B.1 CONTROL STRUCTURES AND MICROPROGRAMMING
  B.5 REGISTER-TRANSFER-LEVEL IMPLEMENTATION
      B.5.1 Design
          Subjects: Arithmetic and logic units

General Terms:
Design, Languages, Performance