1. A system for accessing shared information at a main memory level in a computer complex comprising a plurality of computers operatively coupled to one another for data processing, each computer having the capability of being either a host computer or a slave computer, at least one of the computers having a shared information storage region in its main memory means, each said computer comprising: (a) main memory means for storing at least local data to be processed within said computer; (b) means, coupled to said main memory means, for controlling the reading of data therefrom and the writing of data therein; (c) arithmetic control means, coupled to said main memory control means, for controlling data processing operations involving said local data; (d) computer system linkage memory means, coupled to said main memory controlling means, for enabling access to said main memory means of all other computers through their corresponding computer system linkage interrupt means at a machine word level, thereby permitting the writing of shared information stored in the main memory means of the one of said computers into said main memory means of all other computers; (e) alarm means, coupled to said arithmetic control means, for detecting a problem in said arithmetic control means; (f) computer system linkage interrupt means, coupled to said arithmetic control means and alarm means, for transmitting an interrupt instruction to said arithmetic control means of all the other computers through their corresponding computer system linkage interrupt means in accordance with a command from said computer system linkage memory means or said alarm means; (g) high speed input/output bus means for connecting said computer system linkage memory and said computer system linkage interrupt means; and (h) means operatively connected to said arithmetic control means for altering one section of a logic address space viewed from each said computer to any one of a plurality of sections of a physical address space so that the logic addresses of the shared information storage region which are respectively viewed from the programs of said computers are identical.