Magnetic tape unit reading system

Claim 2

A magnetic tape unit reading system comprising input means for supplying read data; all 0 byte detecting means having an input coupled to the input means and outputs for detecting from the read data a byte having data bits which are all 0; all 1 byte detecting means having an input coupled to the input means and an output for detecting from the read data a byte having data bits which are all 1; addendum detecting means having inputs connected to the outputs of the all 0 byte detecting means and the all 1 byte detecting means and outputs for detecting all 0 and all 1 bytes as a virtual addendum to the read data by detecting the all 0 and all 1 bytes of the all 0 byte detecting means and the all 1 byte detecting means; timing means having an input connected to an output of the addendum detecting means and an output for timing a specific predetermined period of time starting with the detection of the data as a virtual addendum by the addendUm detecting means; byte counting means having an input connected to the timing means, an input coupled to the input means and an output for counting the bytes of the read data; end data checking means having an input connected to the output of the byte counting means, an input connected to an output of the all 0 byte detecting means and outputs for determining if an all 0 byte is detected by the all 0 byte detecting means during the specific predetermined period of time; and output means connected to the output of the end data checking means.

Claim 3

A magnetic tape unit reading system as claimed in claim 1, further comprising error data means for supplying error data, +1 adding means having an input connected to an output of the end data checking means, an input coupled to the error data means and an output connected to the output means for adding 1 to the error data if the addendum detecting means fails to detect all 0 and all 1 bytes as a virtual addendum and for storing the new sum when the end data checking means determines that no all 0 byte is detected by the all 0 byte detecting means during the specific predetermined period of time, dropout detecting means having an input connected to the input means and an output for detecting a dropout on a magnetic tape when the read data supplied by the input means is read from a magnetic tape, error track holding means having an input connected to the output of the dropout means, an input coupled to the error data means and an output connected to an input of the addendum detecting means, an input of the all 0 byte detecting means and an input of the all 1 byte detecting means for storing data of a portion where there is a dropout on a magnetic tape and for determining coincidence of data of a portion having a dropout detected by the dropout detecting means and the error data supplied by the error data means, error data holding means having an input coupled to the error data means, an input connected to the addendum detecting means, and output connected to the addendum detecting means and an output connected to an input of the +1 adding means for storing error data supplied by the error data means and data from the error track holding means and for subtracting 1 from the error data each time the addendum detecting means detects all 0 and all 1 bytes as a virtual addendum.

Claim 4

A magnetic tape unit reading system as claimed in claim 2, wherein the output means comprises end data error signal generating means having an input connected to an output of the end data checking means, an input connected to the output of the error track holding means, an input connected to the output of the +1 adding means and an output for transmitting the signal of the +1 adding means and the detected error track signal of the dropout detector for processing and return to the error data means as an end data error signal.

Claim 5

A magnetic tape unit reading system as claimed in claim 3, wherein the error track holding means comprises first memory means and second memory means for storing the track having a dropout, said first memory means storing the number of the track having a dropout and said second memory means storing error data of the portion having the dropout as transmitted by the end data error signal generating means and returned to the error data means.

Claim 6

A magnetic tape unit reading system as claimed in claim 3, wherein the error data holding means comprises memory means for storing signals from the addendum detecting means and data from the error data means, said memory means storing data received directly from the error data means and including means for making the content of said memory means 1 if a signal is received from the addendum detecting means when no data is stored in said memory means and means for adding 1 to the content of said memory means and for storing the result of the addition in said memory means if A signal is received from the addendum detecting means when specified data is stored in said memory means.