Abstract: If parallel computers have to become general purpose tools, it is necessary to develop services that make transparent its internal characteristics and make parallel programming easier. Trying to fulfil this goal and to have a platform for the test and evaluation of mechanisms for a parallel architecture, a microkernel called TransCom has been designed for a distributed-memory multiprocessor. The microkernel includes services to virtualise the communication network, which provides a parallel programming model based on message passing. It has been designed in two steps: a tiny system core called TransRouter providing simple functions for data transport and routing, but without protocol services, and a basic set of communication primitives, on top of the TransRouter and including its own communication protocols, to make up the TransCom. Concurrently with the development of the microkernel, some studies and simulations have been undertaken in order to virtualise the "processor resource" through the load distribution among the processors.