Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!cbmvax!grr
From: grr@cbmvax.UUCP (George Robbins)
Newsgroups: comp.sys.amiga
Subject: Re: 5 1/4 Latch circut and A2000
Message-ID: <2887@cbmvax.UUCP>
Date: Wed, 2-Dec-87 19:57:31 EST
Article-I.D.: cbmvax.2887
Posted: Wed Dec  2 19:57:31 1987
Date-Received: Sun, 6-Dec-87 07:38:59 EST
References: <1151@sugar.UUCP>
Reply-To: grr@cbmvax.UUCP (George Robbins)
Organization: Commodore Technology, West Chester, PA
Lines: 24
Keywords: Latch PCcopy PCutil PCformat Floppy

In article <1151@sugar.UUCP> ssd@sugar.UUCP (Scott Denham) writes:
> 
> interesting 'blue' box. My problem is that since upgrading to a B2000
> (4.2 rev) the drive no longer wants to work as a 'PC' drive, though its's
> fine as a 40-track Amiga device. The symptoms are 'root directory full'
> from PCcopy and 'error -4' from PCformat. Oddly enough the drive still
> works fine in both modes on the old 1000. Can anyone shed any light on
> what 'error -4' might mean, what differences might exist between the 
> 1000 and 2000 implementations of the external disk interface, and 
> whether or not such a latch circuit needs any additonal 'tweeks' to 
> operate on the 2000 ??

You might want to make sure that your drive doesn't have any heavy-duty
180 or 220 ohm terminating resistor packs.  The A1020 drive is specified
to use 1K terminators to avoid overloading the driver circuitry.  The
A1000 used discrete TTL buffers to drive the floppy signals, whereas the
A500 and A2000 use a modified 8520 with high-current outputs to drive
some of the signals, and a TTL buffer only on the signals that come from
Paula via Gary.

-- 
George Robbins - now working for,	uucp: {uunet|ihnp4|rutgers}!cbmvax!grr
but no way officially representing	arpa: cbmvax!grr@uunet.uu.net
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)