Efficient Implementation of the Graphical Input/Output for Smalltalk-80

Abstract

A highly interactive system such as Smalltalk-80 requires high performance at the user interface. An implementation of the Smalltalk virtual machine, to be acceptable, must be tuned to achieve good efficiency of its I/O operations. This paper describes our experiences gained from implementing the v-machine on a specific hardware configuration in which we have available a separate I/O-processor for driving the bitmap terminal. We respecify the Smalltalk-80 I/O-primitives in Smalltalk in terms of a set of more low-level operations. The latter are designed to be per-formed by the I/O-processor in parallel to the operation of the virtual machine on the main processor of the workstation. We conclude in demonstrating the usefulness of this type of hardware and software structure.