Tape backup with Everex card

[debra at research.att.com]

Larry Snyder wrote:

>Has anyone been able to get the Wangtek tape driver supplied
>with 386/ix working - and verified their backup via a restore?
>...
>My controller is an Everex 2/3 length board installed at irq 5
>and 300 - 301 which is supported and works fine using the
>Everex tape backup utility.

I have the same problem with AT&T Unix System V r3.2u and a Wangtek
tape drive connected to the Everex 2/3 board. I verified that the
AT&T Unix works well with the AT&T supplied board on a 6386, but
not on my Everex 386/25 and the 2/3 length Everex board.

The Everex (dos) tape utilities find no errors.
The AT&T Unix utilities find no errors either, but nevertheless there
are errors on the tape. The driver does not detect soft or hard errors
but while writing about 10 to 50 bytes are garbled on a 60 megabyte tape.
Reading a tape (with a test pattern) produces identical errors on every
run, so the errors are written onto the tape. The read after write test
which the drive/controller combination performs all by itself seems not
to notice the errors, which suggests that the Unix driver hands faulty
bytes to the controller.

So what's going on? What's special about the Everex 2/3 card that's
different from the full-length PC-36 card that AT&T supplies for the
Wangtek drive, or what's special about the Unix driver that causes the
Everex card to malfunction?

Any help would by highly appreciated.

Paul.
(debra at research.att.com)