Date   : Sun, 05 Sep 1982 10:04:00-EDT
From   : Roger L Long <BYTE@Mit-Mc>
Subject: 1771 -> 179X conversion

The 1771 accepted both 00h and FFh for filling interrecord gaps, while
the 179X requires that you use FFh.  If you change the format program
you use to format diskettes on your single-density system to use FFh
for your fill bytes, the diskettes written will be compatible.  Also,
a simpler solution would be to just format a batch of diskettes on the
system with the 179X controller (which must already use the FFh fill
byte) and then copy your old diskettes onto these newly formatted
diskettes.

Before you go to a lot of work, I'd at least try reading some of your
old diskettes with the 179X.  When the incompatiblity was first
discovered, I already had my 1771 system, and went ahead and changed
my FORMAT program.  I would assume that Tarbell then started shipping
out single-density controllers with compatible software.  I would
also assume that any distribution diskette would be compatible,
as I've never had any problem reading such diskettes on my double
density systems.

       -roger