FECO TP # 9

	FECO:	TP # 9
	MODIFICATION NO:	N/A
	PRODUCT:	TRAVAN TAPE DECKS
	SUB-ASSEMBLY:	N/A
	ESTIMATED MAN HOURS:	N/A
	CLASS OF CHANGE:	INFORMATIONAL
	REASON FOR CHANGE:	INTRODUCTION OF TRAVAN TAPE DECKS

INTRODUCTION

1. The Travan technology was developed by the tape manufacturer 3M together with tape deck manufacturers.
2. The Travan decks use 8mm or 0.351 inch tape. At present there are four types, T1-T4, and there can be up to 72 tracks across the width of the tape. The T1 having only 36, the T3 has 50; whilst the T4 has 72.
3. In use the tape is not withdrawn from the cassette to be wrapped around the head as the helical scan technology, but the head presses on the tape as it is wound back and fourth.
4. The single head combines the read and write function.
5. Some heads have 1 write and 1 read function, like the Seagate CTT8000, a T4 unit that EDP uses. Others can have 1 write and 2 read functions. This type can read whilst writing, and utilises the read function to error check, and then correct if necessary.
6. A serpentine method of writing data is used. Beginning at the centre of the tape, the data is written down in a track, then when the end of the track is reached, the tape reverses, then writes the data down on a second track, going the other way. When it gets to the end of the second track the tape changes direction again and continues writing back along a third track. The tape reads and writes in both directions.
7. The tape head does move up and down across the tape, senses the position of a track and determines if this is the correct track. If this is wrong then the tape unit stops working, and generates a HARDWARE ERROR.
8. See the diagram below of a tape with tracks A-K. The data is first put down on the track in the centre of the tape, track F. At the end of the track, when the tape reverses, the data is then put down on the track above the centre, track E; then on track G, then track D etc.

_____________________________________________

A A A

C B B B

A C C C

B T D END OF SET D D E

A E E E

O L F START OF SET F F O

O G G G

T G H H H T

U I I I

E J J J

K K K

_____________________________________________

END TRACK MARKERS END TRACK MARKERS

9. At the beginning of the tape is the Tape Header and the Catalogue of contents of the tape. At the end of the tape is the usual End of Tape, EOT. At the beginning and end of each track there are markers. Markers are also written at the beginning and end of every set of data.

 10. TYPES OF TAPE UNITS

11. TYPES OF MEDIA

            There are three different types of Travan tapes used:-

            They should be used as follows:-

NOTE.

12. 1. INTRODUCTION.

12. 2. TECMAR TS420C CONFIGURATION.

Jumpers 1-3 set the SCSI address ID as below.

12. 3. COMPATIBILITY.