Electronic mail system - has terminal with memory having main text area that cannot be manipulated

摘要

The electronic mail system has a number of local area networks, LAN, (17, 17) that are connected to a main telephone or communication network (19) by interface modules (17s, 17's). Each local network has a number of terminals (17T, 17'T) that has receiver and transmitter facilities. The terminals have an internal bus that supports an interface, transmitter/receiver, identification unit, document memory used as a post box, data memory, I-U unit, main memory with programme routines, keyboard, display and a CPU. The main memory has a region to store additional data to prevent any changes being made in a document during the communication cycle. ADVANTAGE - Prevents any manipulation of documents.