Multiple port communications adapter apparatus

A universal port communications adaptor, comprising:

• a plurality of universeal synchronous/asynchronous driver receiver port interface circuits (USARTs);
• a like plurality of service request signal means connected to said USARTs;
• a DIAC for making priority selections and issuing DMA or interrupt control signals, said DIAC having said plurality of service request signal means connected thereto;
• and
• a microprocessor, a memory and interconnecting control data and address busses connected therebetween;
• said busses being connected to said DIAC and to said plurality of USARTs for communicating data between said USARTs, said microprocessor and said memory in accordance with said DIAC's priority selections and interrupt or DMA control signals.

A multi-port communications control system, comprising:

• a plurality of communications port interface circuits;
• a like plurality of service request signaling means connected to said interface circuits;
• a bidirectional data bus, said bus being connected to said interface circuits to deliver or receive data therefrom according to service requests therefrom;
• a DIAC service mode controller connected to said plurality of service request signaling means;
• a microprocessor;
• a memory means for storing instructions and data;
• an address bus;
• said address bus and said data bus interconnecting said microprocessor and said service mode controller and said memory;
• and
• said microprocessor providing initial control parameters to said service mode controller in accordance with said instructions in said memory for defining the mode of service to be accorded to each said communications interface circuit by said service mode controller.