| 摘要 |
PURPOSE:To permit simple updating, deletion, etc. of volume by writing nothing at every specified data byte on a medium if the same is necessary data and by writing a specified pattern if the same is the data to be deleted. CONSTITUTION:In ordinary data writing, a write data signal 101 is supplied through a data bubber 2 and a write controlling circuit/moculating circuit 3 to a selecting circuit 4. In the circuit 4, the signal 104 from a special pattern generating circuit is not made effective and only the data parts are selected and the data N is transmitted as write data 107 to the medium. On the other hand, if the updating of files is necessary and when the data in the part of an address N+1 is going to be deleted from the medium, the special pattern generating circuit 1 is made effective and FLAG A is written on the data. In the stage of reading out the data from the medium into which the data is written, the special pattern 103 is announced to the device by a special pattern detecting circuit 5 as the effect that the data in said sector is the data to be deleted. |
