Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!rutgers!cbmvax!fred
From: fred@cbmvax.commodore.com (Fred Bowen)
Newsgroups: comp.sys.cbm
Subject: Re: C64 Disk Drive Error Light Question
Message-ID: <13845@cbmvax.commodore.com>
Date: 16 Aug 90 20:19:21 GMT
References: <90219.131526TESSIER@YaleVM.YCC.Yale.Edu> <1990Aug8.054152.14522@ccu.umanitoba.ca>
Reply-To: fred@cbmvax (Fred Bowen)
Organization: Commodore, West Chester, PA
Lines: 30

In article <1990Aug8.054152.14522@ccu.umanitoba.ca> Dan Fandrich writes:
>>I have an old (8 years?) disk drive on which the error light is blinking at
>>power up.  I have been unable to clear it or determine its cause... any ideas?
>
>Sounds to me like your ROM is gone.  Most of that excruciatingly long delay
>at powerup is the drive calculating a checksum of the ROMs.  If it detects
>an error, it's twinkle time.  Try swapping ROMs with a friend's drive and
>see if things start working again.

Which drive?  I'll assume it's a 1541 (eight years sounds about right :-)
The 1541 powerup diagnostic blinks a pattern to indicate what's bothering it:

			1 blink	= RAM page zero bad
			2	= ROM at $C000 bad
			3	= ROM at $E000 bad
			4	= RAM bad

Use this info as a guide- obviously if the ROM containing the diagnostic is bad,
or the RAM it tallies the checksum in is bad, who knows what kind of blinks
you'd see (the diagnostic is in the $E000 ROM).  If you need to replace a ROM,
it'd be a good time to consider something like JiffyDOS (check the magazines-
I'm not a Jiffy customer or user, personally).


-- 
Fred Bowen			uucp:	{uunet|rutgers|pyramid}!cbmvax!fred
				domain:	fred@cbmvax.commodore.com
				tele:	215 431-9100

Commodore Electronics, Ltd.,  1200 Wilson Drive,  West Chester,  PA,  19380