XSTORE XSTORE is a store test program written by Terry Froggatt. The program runs eight "write" phases, in which the whole store module is first set to a known pattern. Each is followed by a "read" phase which, for each word, checks that that word is right, then inverts it and checks that that is right, then sets it back and checks that's OK. The first 2 phases set all zeros, and then all ones, so give a straighforward go/nogo test of the data bits. The next 2 phases write the address to the location, ("ascending"), then the inverse of the address, so a different value is written to every word, which should flush out a dud address line driver. The next 2 phases use the worst-case chequerboard pattern specific to the store of a 920B or 903 as in X2. (The final 2 phases just use chequered addresses). A three-word output indicates an error, giving the address, the expected data, and the error (actual-expected). Only the first 20 errors of each phase are printed. A two-word output is given at the end of each phase, module address (8192*N) + test number (0 to 7), then the number of errors from that test.