On Thu, Aug 30, 2018 at 10:31 AM William Pechter <pechter@gmail.com> wrote:

> At least in the old days drives had Write Protect switches.
>
Not the issue - both disks were RW.  I was running as root and ran a
program that lacked a check it shoud have had it (because I was lazy and
never put it in there).



> Screw IBM for the in cable drive select lines on diskette
>
You of course realized that was because of field service issues of course.
 Setting all floppies (and later ST-506 disks) on the PC and using a twist
in the cable meant they did not have to ask FS folks to set the jumpers
properly.




> and leaving off Write Protect on hard disks.  Some disks had write protect
> jumpers on the boards...
>
Hmmm.. I thought all disks at least had a strap.   WD, CDC, Seagate,
Shuggart, Toshiba all supported the strap.  The IBM disks I remember did
not also, but I'll take your word for it, it would have been like them to
have removed it to save the connector cost.




> They should have been The STANDARD.
>
Hmmm.. I'm not at home, but I think I have both the ST-412/506 and ESDI
specs in a filing cab somewhere.  I thought the standard did defined it.
(Intel blocks 'bitsavers.org' for some reason so I can not look online but
I think  http://www.bitsavers.org/pdf/seagate/ST412_OEMmanual_Apr82.pdf is
likely to have it in there).

Clem

>