Operating Systems (OS)

Abstract

In Chap. 4 (Software), the user interface (interaction) with the computer hardware (Chap. 5) is implicitly specified as being via a compiler program which translates user-defined high-level language programs (e.g. C++ programs) into low-level assembly language programs. The latter are parsed into a sequence of simple machine-like operation-based statements (like X=Y+Z) that can be executed more-or-less directly by MIPS-type hardware computers configured with registers and processors, as explained in Chap. 5. This application-software (e.g. C++) interaction with the computer hardware, the user interface, is supported by little more than a hardware device called a program counter in conjunction with straightforward state-control logical circuits, following Turing’s basic ideas on computation Control rather closely. However, in this early method of treatment of the rather simple user interface, there is no account given of certain implicit and important details, such as how the C++ user gains access to the compiler or to other assumed supporting facilities such as library subroutines called in the high-level user program or to data-file storage. For the early instances of software-hardware interactions, this naive approach to the user interface was sufficient. However, by the 1960s, hardware and application software programs had both become much more sophisticated and the user interface more complicated.