transfer from explorer to Symbolics

[Doug Evans <DE%phoenix.sch.symbolics.com@RELAY.CS.NET>]

    Date: Wed, 22 Mar 89 15:27:13 N
    From: baechler%elma.epfl.ch@CUNYVM.CUNY.EDU


    A friend of mine who uses an Explorer (don't laugh, this happens), created some
    utilities that i would like to use. As our machines are not interconnected, he
    created a carry-tape for the transfer. The density was specified in an item
    strangely named "protocol". There were two possibilites: QIC-24 and 6250. As
    6250 didn't work (I don't know why), we used the Qic-24.

6250 didn't work as density can only be specified for reel-to-reel
tapes.  Density for cart tapes on all Lisp Machines is fixed (by the
type of tape drive) at 8000 ftpi.

However, there are two different incompatible formats used for cart
tapes: QIC-11 and QIC-24.  Apparently (according to the manual), the
only difference between formats is a group of bytes called the Block
Address (which the manual says is used for error correction and tape
positioning).

    When I tried to read that tape one one of our Symbolics, I got an error
    message telling that the tape was not a carry tape. I tried to find a symbol
    called QIC-24 to specify the density, but there were not, so i am unable to
    read that tape.

All tape drives on Symbolics are preset to use QIC-11 format.  According
to the manual, certain models of tape drives can be switched between
QIC-11 and QIC-24 via interface commands (which aren't currently
supported in our tape software), but I doubt that our lisp machines use
those models. However, the format can be changed if desired if you have
access to the tape drive.  There is a block of pins near where the
50line ribbon cable connects to the drive that are labeled with letters
(AA, BB, CC, DD, EE, FF, HH, KK, ZZ).  The CC pins determines what
format is used at power-up time: no shorting jumper across the CC pin
sets for QIC-11; a shorting jumper across the CC pins sets for QIC-24.

    My question is: is it possible to read on a Symbolics a carry tape created on
    an explorer ? If yes, What must I do to do this ? Is there something special
    to do on the Explorer in order to do this ?

As we have no Explorers around here, I can't help you with that side.
On the Symbolics machine, you could put a shorting jumper on the CC
pins, enabling the drive to write and read tapes that would be compatible
with the Explorer.  Please remember that with the jumper installed, the
tape drive will be unable to read or write compatible tapes for other
Symbolics machines.

To everyone else listening on SLUG, please note that there is no
advantage to using QIC-11 or QIC-24 formats, other than for compatiblity
purposes.  The different formats have nothing to do with density or tape
capacity.