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               │  5. Field  of control signals.     ║
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 Includes:
           I   - signal of reading from external device;
           O   - signal of record on external device;
           LCK - LOCK - signal for fixing of the daisy-chains conditions
                 (it is used before vector read);
           IA  - INTA - signal for acknowledgement of the interruption for 
                 device in daisy-chain and for reading from DB
                 vector of the interruption;
           R   - signal of the reading from memory;
           W   - signal for record in memory;
           EWH - signal for record in higher bits of the address register;
           EWL - signal for record in lower bits of the address register.