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Write

The WRITE operation is initiated by Software writing Mode WRITE to register C. An interrupt is asserted to confirm that mode has changed.

The Drive makes preparations to start writing starting at the current tape location. Unlike with READ operation, in this case the Drive does not check for GAPs.

Once the Drive is ready, it asserts an interrupt and Software responses by writing the first byte to register D. The Drive's circuitry senses this write operation and starts encoding and writing the byte to tape. Once finished, a new interrupt is asserted and Software writes the next byte to D in response.

This process continues until Software decides to finish. Normally this occurs when an entire block has been written. Software are then expected to write Mode Make GAP to register C. In response, the Drive let a GAP in the tape and STOPs automatically. An interrupt is asserted because the Mode changed (from Make GAP to STOP).

This completes the writing of a block on tape. Software will possibly initiate a new WRITE operation to write the next block.