A computer assembly comprised of a plurality of modular units which are readily connectable by pluggable terminals to permit quick interchangeability and/or replacement of certain units by untrained and unskilled personnel. The computer assembly includes a docking bay module provided with a number of external connectors for connection to equipment such as a keyboard, printer, cash register, etc., and a power supply plug. A CPU module containing the logic circuitry is slidably mounted in and out of the docking bay module and is readily connected by mating pluggable terminals to the various equipment linked to the external connectors on the docking bay module. A peripheral bay module may be added to the docking bay and CPU modules to function as a file server station in a local area network environment. The CPU module is quickly and conveniently replaced by unskilled personnel for maintenance and repair purposes. The CPU module is constructed in such a way that cooling of the circuit components is accomplished without the presence of a cooling fan. Because the CPU module is quickly and easily replaced in the docking module by unskilled personnel, the customer need not maintain an inventory of spare parts but may rely on overnight delivery service from a maintenance contractor for a replacement CPU module.