Re: Apple disk drive...

["Bill Garber" <willy46pa@comcast.net>]

Thank Michael, I wasn't aware of that, but it is the
same principal as the rest of the system must be interrupted
in order to read/write to/from the drive. ;-)

Bill @ GarberStreet Enterprises
http://garberstreet.netfirms.com


Michael J. Sch�lke <mjschuelke@hotmail.com> wrote in message
MPG.191f959acdf4e3af9899a4@news.t-online.de">news:MPG.191f959acdf4e3af9899a4@news.t-online.de...
> Michael Black wrote:
> > One reason the Commodore (and at least some Atari) drives are slow
> > is that they are connected to the computers via a serial port.
> > That tends to be relatively slow, if for no other reason than that
> > the bits go one at a time rather than in parallel.
>
> No -- the CBM drives are slow because the serial port is controlled
> directly by the processor, shifting out the bits in software, rather
> than using a hardware shift register.
>
> This was introduced as a workaround for a bug in the VIC-20's 6522 VIA,
> kept in the C-64 for compatibility (even though the bug was fixed in the
> 6526 CIA), and only remedied in the C-128 in combination with the
> 1570/1571 drives.
>
> Regards,
> Michael


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