Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!utgpu!water!watnot!watmath!clyde!cbatt!ihnp4!ihwpt!knudsen
From: knudsen@ihwpt.UUCP
Newsgroups: comp.sys.m6809
Subject: Newdisk Head-Banger Bug
Message-ID: <1540@ihwpt.ATT.COM>
Date: Fri, 20-Mar-87 18:48:48 EST
Article-I.D.: ihwpt.1540
Posted: Fri Mar 20 18:48:48 1987
Date-Received: Sun, 22-Mar-87 17:18:54 EST
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 25
Keywords: os9

A while back, one of the guys who helped polish up Dave Lewis'
Newdisk posted a little patch to fix head-banding on drives
that were jumpered to load heads on select (not just motor on).
Simple patch -- you removed a couple lines of assembler source
that deselected the drive instantly.

Well, you may need it!  I found that it is extremely unreliable
to write to such a drive with the deselect code intact.
I should say reliable -- you get about 75% bad sectors written
on a BACKUP!  When I write (including backup) to another drive
with no head-load solenoid, I have no problems.

Thought you'd like to know that ripping out those two lines
of code is a "mandatory option" if you have your drives jumpered
that way.  Hmmm, this explains why my Coco3 has had problems
writing disks--its drive is head-loaded too.

Guess I'll send Dave his $10 -- after I finish rebuilding a half
dozen boot files ... mike k

PS: Has anyone got a DISTO parallel interface to work reliably
on OS9?  Or a DISTO controller to work on Coco III?
-- 
Mike J Knudsen    ...ihnp4!ihwpt!knudsen  Bell Labs(AT&T)
>>>DRUGS are for WIMPS who can't handle SCIENCE FICTION<<<