Path: utzoo!attcan!uunet!ginosko!usc!apple!agate!ucbvax!UIAMVS.BITNET!CMDSENPG
From: CMDSENPG@UIAMVS.BITNET (Steven Nelson)
Newsgroups: comp.sys.apple
Subject: UDC problems
Message-ID: <8908220011.aa16711@SMOKE.BRL.MIL>
Date: 22 Aug 89 04:07:00 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 24

Several messages have commented on problems with the Universal Disk controller
(UDC) and 3.5" drives.  As I currently use 3 UDC's on three different
Apple computers, I want to share my observations.  I have learned one
important fact about the UDC which is NOT mentioned in its scant
documentation.  The UDC does NOT initialize correctly unless booted
, or at least attempted to be booted.  On one of my systems, I prefer
to boot from my Sider (slot 7) into ProDOS and Davex command shell.
Then I 'boot -s5' to init the UDC in slot five (no disks in either
Laser drive).  Failure to boot will cause the UDC to return to the
Applesoft basic prompt.  I call -151 to get into the monitor, then
ctrl-Y to return to Davex.  After that I seem to be able to use the
UDC reliably, but if I forget to 'boot' it, I'll most certainly
destroy a block on occasion.  However, properly init'ing seems to
make the UDC behave 99%+ of the time.  Old 400k drives from the Mac
also seem to work if I boot from them, but will fail very often if
I access them without trying to boot the UDC.  Incidently, I use the
400k drives and UDC with a Apple II+.  My other 2 UDC's and Laser 800k
drives are used in enhanced IIe's - one with a Zip chip.  The UDC slot
MUST be set to 1Mhz (normal) speed.  The UDC will read at the fast
chip speed but will not write correctly.

I don't know what to think about the claims that the UDC does not work
with the Apple II+.  I'm quite satisfied with my UDC's now that I know
how to 'boot' them!  At least on II+'s and IIe's.