Disk reproducing apparatus

A disk reproducing apparatus for controlling the entire operation by cooperation between two microcomputers, comprising:

• a first microcomputer for performing control of an operation for reproducing information recorded on a disk which is a disk-shaped record medium, and
• a second microcomputer for performing control of an operation for outputting information reproduced from the disk, wherein
• four signal lines for respectively transmitting a control signal BUSY/-RDY which is sent from said first microcomputer to said second microcomputer and indicates whether or not said first microcomputer is in a communicable state, a control signal BUSCLR which is sent from said second microcomputer to said first microcomputer and instructs said first microcomputer on initialization, a clock signal sent from said first microcomputer to said second microcomputer for synchronization in the case that said second microcomputer communicates with said first microcomputer, and a data signal for conducting two-way clock synchronous serial communication between said first microcomputer and said second microcomputer are provided between said first microcomputer and said second microcomputer, and
• a sending side sends sending target data formed by adding a byte for error detection in which each bit is exclusive OR of a corresponding bit of a byte which is a sending target after a byte which is the original sending target, and when a byte corresponding to the byte for error detection is received, a receiving side performs error detection of received data using said byte, and
• in the case that said first microcomputer is in the receiving side, when an error is detected in received data, the control signal BUSY/-RDY is not shifted to a state indicating communicability, and when the control signal BUSCLR shifts to a state of instructing initialization, a communication state is initialized and the control signal BUSY/-RDY is shifted to a receivable state, and then the control signal BUSY/-RDY is shifted to the state indicating communicability, and
• in the case that said second microcomputer is in the sending side, when the control signal BUSY/-RDY is not shifted to a state indicating that said first microcomputer is communicable at a point in time when predetermined time elapses since the last byte of the sending target data is sent, it is decided that a communication error occurs, and the control signal BUSCLR is shifted to a state of instructing initialization, and subsequently, after the control signal BUSY/-RDY shifts to the state indicating that the control signal BUSY/-RDY is communicable, the sending target data sent immediately before is resent from the first byte after shifting the control signal BUSCLR to a state in which initialization is not instructed, and
• in the case that said second microcomputer is in the receiving side, when an error is present in received data, the control signal BUSCLR is shifted to a state of instructing initialization, and subsequently, after the control signal BUSY/-RDY shifts to a state indicating that said first microcomputer is communicable, the control signal BUSY/-RDY is switched to a sending state after shifting the control signal BUSCLR to a state in which initialization is not instructed and the sending target data sent immediately before is resent from the first byte, and
• in the case that said first microcomputer is in the sending side, when sending of all the bytes of the sending target data is completed, after maintaining the control signal BUSY/-RDY at a state in which communicability is not indicated until predetermined time elapses, the control signal BUSY/-RDY is shifted to a state indicating communicability after being switched to a receiving state, and also, when the control signal BUSCLR shifts to a state of instructing initialization by the time when the predetermined time elapses since sending of all the last bytes of the sending target data is completed, a communication state is initialized to shift to a receivable state, and then, the control signal BUSY/-RDY is shifted to the state indicating communicability.