ON-LINE COMPUTER SYSTEM CAPABLE OF SAFELY AND SIMPLY PROCESSING A MESSAGE SIGNAL

For processing an input message signal into a processed message signal, an on-line computer system comprises a saving buffer for memorizing as a memorized message signal a received message signal supplied from a message receiving circuit for receiving the input message signal. A processing unit produces a first request signal to be supplied with the received message signal as a first supplied message signal and produces a second request signal to be supplied with the memorized message signal as a second supplied message signal while processing the first and the second supplied message signals into the processed message signal. The memorized message signal is erased from the saving buffer when the processing unit produces a normal end signal representing a normal end of processing. The memorized message signal may be erased from the saving buffer when the processing unit produces the first request signal. The processing unit may be supplied with the second supplied message signal by producing a third request signal when the processing unit fails to process the first and the second supplied message signals.