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.