Quantum Audio Travan 40 Tape Drive STT3401A - Manual (Page 124)

Chapter 6 Travan 40 tape format
Page 116 Seagate Travan 40 Product Manual
Frames are numbered indirectly using the 26 most significant bits of the Physical
Block Address. Frame operation is controlled by the drive and generally invisible to
the host. Frames are used primarily as a means to control the error correction
operations.
Frames can be overwritten with new data frames or an End-of-Data (EOD) frame.
Append operations can only begin at EOD.
An underrun is not allowed in the middle of a frame, regardless of the frame type.
Filler blocks can be used to complete a frame as long as they are not used interior to
a logical block.
A frame that cannot be completed on one track is rewritten in its entirety at the
beginning of the following track. Frames are not split around corner turns.
The general frame layout—470 data blocks and 40 ECC blocks—is illustrated in the
table below.
Data
Block
0 Data
Block
1 Data
Block
2 ... Data
Block
470 ECC
Block
0 ECC
Block
1 ... ECC
Block
39
The four types of frames are as follows:
•
Data frames contain data and information blocks in addition to ECC blocks.
•
The Media Header frame contains only Media Header blocks and ECC blocks.
This frame is recorded as the first frame on the Directory Track.
•
Track ID frames are recorded as part of the pre-formatting process of the
cartridge. These frames are easily distinguished from other frame types because
they reside entirely outside of the data region of the tape.
•
An EOD frame is an absolute indicator of the end of the recorded data. It is
recorded after the last frame containing host data upon terminating a Write
process.