Ref: 13420009
Title: Using 250 MB and 150 MB Tapes on the Same Tape Drive
date: 12/5/89

Copyright 3Com Corporation, 1991.  All rights reserved.

The same tape drive is used to read both 250 MB and 150 MB tapes;
however, the 250 MB tape is longer and thinner than the 150 MB tape.
It is as though you are using a 90 minute cassette instead of a 60
minute cassette in your tape deck, except that if you start using the
longer tape (the 250 MB option), 3Com does not guarantee that the
tape drive will be able to read 150 MB tapes in the future.

This is because the thinner tape naturally vacuums onto the head of
the tape drive and eventually wears it down more around the edges.
The tape drive head becomes bowed and loses signal from the thicker
tapes, which will not vacuum down as easily.

How quickly the problem occurs depends on the material the
manufacturer uses to make the tape heads.  The harder the head, the
less wear it will experience.  Since we do not know how long it takes
to wear a head down to the point where it cannot read a 150 MB tape,
3Com recommends that, once you use the longer tapes, you not use
the shorter ones again.


