Re: Did Commodore cheat with the quad density floppies?

Den Fri, 4 Jan 2019 12:12:09 +0100 skrev Gerrit Heitsch
<gerrit@laosinh.s.bawue.de>:
> On 1/4/19 11:51 AM, Francesco Messineo wrote:
> > On Fri, Jan 4, 2019 at 11:49 AM Gerrit Heitsch
> > <gerrit@laosinh.s.bawue.de> wrote:
> >>
> >> On 1/4/19 10:47 AM, silverdr@wfmh.org.pl wrote:
> >>
> >>> Yes. Never had a diskette, which made you open the drive and
> >>> clean the heads afterward? ;-)
> >>
> >> I had that a lot when imagine old disks... Really learned to love
> >> my Oceanic 168 drive I use for this purpose.
> > 
> > What's better on the Oceanic? I'm curious.
> 
> The drive mechanism they used is direct drive (no belt to worry
> about), looks more sturdy, it is more compact than a 1541 or even
> 1541-II, uses a metal case and is a full TTL implementation, meaning
> no custom chips. Runs perfectly with an original 1541-II ROM and uses
> the same PSU connector as the 1541-II, you can use the same PSU
> (5V/700mA-1A and 12V/500mA) for both.

Side track:

Those power supplies, for 1541-II and 1581, are prone to the same kind
of failure as the VIC 20 CR, C64 and Plus/4 power supplies are, i.e.
failure resulting in over voltage. It seems like the drives aren't as
easily damaged as the computers though. One factor here might be that I
assume that all motors are driven from 12V and thus the 5V power is
rated at only slightly above what all logic actually consumes, making
the voltage drop over the regulater lower than on a computer where the
transformer is able to power various peripherals that might not be
connected to the computer. Also different chips might be more sensitive
to over voltage than other chips.

Anyways it seems like a bad idea to run an expensive 1581 on it's
original power supply even though those drives aren't known to die if
the power supply dies. (Or maybe they do, but there are so few of them
that the fact isn't widely known?).

Another side track: There is some other third party drive for Commodore
8-bit computers, called something like FD-148. Instead of using the
same PSU as 1541-II and 1581, it instead uses the same PSU/transformer
as the Spectravideo computers :)

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