The instructions available were : Add, Subtract, multiply-and-add, AND-and-add ( called " Collate " ), shift Left, arithmetic shift Right, load multiplier register, store ( and optionally clear ) accumulator, conditional Goto, read Input tape, print character, round accumulator, no-op, and stop.
22.
The keyboard of the CPT 4200 had action keys for " skip " and " read " and mode keys for " word ", " line ", " paragraph, " and " page . " Pressing " read " transferred a word, line, paragraph, or page, depending on which mode key had been selected . from the input tape to both the paper and the output tape.
23.
The states of " M " ( described by the position of its head on the input tape and the configuration of the log-space working memory ) can be thought of as the vertices of a directed graph, and the transitions of " M " can be thought of as edges in this graph . " M " accepts an input string whenever there exists a path in this graph from the vertex that represents the starting state to a special vertex that represents any accepting state.
