Using language C for real-time control of microprocessor systems with small memory
1982; Elsevier BV; Volume: 5; Issue: 1 Linguagem: Inglês
10.1016/0745-7138(82)90039-2
ISSN1096-374X
Autores Tópico(s)Real-Time Systems Scheduling
ResumoThe manufactures of several 16-bit microcomputers are now adopting the UNIX operating system developed at Bell Laboratories which is written in the high level language C. However, UNIX is not a real-time system, and this is a drawback for the engineer who may wish to use a microcomputer for control purposes. This paper describes work which has been carried out using a C crosscompiler running under UNIX on a PDP1140 minicomputer which can produce code suitable for the Intel 8080 and 8085 processors. Support routines have been written in a language similar to Intel assembly code (A-Natural), which can be linked in to allow the construction of programs written in C which will run in real time on the processor. Many routines (for example interrupt service routines) can be written either in C or in A-Natural, and the division of labour between the two languages is discussed. The aim of the project is to develop compiled code which is as concise as possible, so that the C routines can be easily used in microprocessor systems with the minimum of memory. The code produced by the crossompiler has been loaded down-line into the RAMs of both 8080 and 8085 based small systems, and the operation of the system is described. As an example of the type of program which can be developed in this way, a system for controlling the speed of a simple motor interfaced to an 8080 microcomputer training system is described.
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