From: Spiro Trikaliotis (ml-cbmhackers_at_trikaliotis.net)
Date: 2006-07-03 20:20:24
Hello Ethan,
* On Mon, Jul 03, 2006 at 07:56:34PM +1200 Ethan Dicks wrote:
> On 7/3/06, Spiro Trikaliotis <ml-cbmhackers@trikaliotis.net> wrote:
> The 34-pin floppy interface (SA-400 drives and such) is a
> reduced-format version of the 50-pin 8" drive bus that preceded it...
[...]
> Back in the day of 8" and 5.25" drives, there were 4 drive select
> options per drive (DS0-DS3) and your controller might be able to talk
> to 2 drives or up to 4 drives.
Well, my very first 3,5" drive (an old, very loud Chinon drive which was
seated in a mechanic to fit into a 5,25" bay; that was back in the days
of the ST251-1 HD) could be selected as DS0, DS1, DS2 and DS3. To me, it
seems that there were two bits on the shugart bus for selecting the
drive (00, 01, 10, 11). The PC seemed to only use 01 and 10 (this is
what you call "positional" selection, isn't it?), ignoring 00 and 11.
This is why I had to switch the drive as DS1 or DS2 to use it.
> That ended with 3.5" drives, as most could only be selected to DS0 or
> DS1,
DS1 and DS2?
Regards,
Spiro.
--
Spiro R. Trikaliotis
http://www.trikaliotis.net/
http://opencbm.sf.net/
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