category C of the library … [checks] the sequence of operations and … the numbers operated upon. … the "parameters" [for these interpretive routines] are simply the orders of … sequence as if they were being obeyed directly. … [these routines print] extra information for checking purposes. … [p. 40] C7, C9, and C12 are rather more … of the program to save time. … [Gill, Proc. of the Royal Society, 1951, p. 552: Program C11 interprets the program while printing a letter for each instruction executed. It is 32 words long.]
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