On Aug 1, 2013, at 1:07 AM, Fred Cisin <cisin at xenosoft.com> wrote:
> The
original Apple II case could be easily open by students and was not
> suitable for school use. (It may not have had the proper UL approval.)
On Wed, 31 Jul 2013, Eric Smith wrote:
UL doesn't "approve" anything. The
Apple II was, however, "UL
Listed", which means that it was tested and certified to comply with
various safety standards. While it's obvious why one usually doesn't
want students to open the computer, doing so does not expose them to
any hazardous voltages.
It never occured to me that any of the changes could have been "safety"
related.
I just assumed that they were an over-reaction to potential pilferage,
and an automatic knee-jerk reaction of "you CAN'T let students into them!"
The story I'd always heard was that it was safety-related, so the case had to be such
that it wasn't easily opened, and couldn't be powered on when it was open. The
Bell & Howell backpack models indeed do have a screw that simultaneously holds the
case lid down and completes the power circuit. It's not really particularly difficult
to open them, but it does serve the purpose of keeping one from monkeying around in there
when the power's on (unless you, you know, put the screw in without having put the lid
on, which is perfectly possible). However, the UL listing mark (standard 126Z) was on all
the regular Apple II and II+es as well once they started using the larger square labels
around early 1980 (white with green ink on II+es, red ink on IIs), so it wasn't a
matter of simply getting any old "UL listed" status. The Bell & Howell
overlaid label (which I think corresponds to having the backpack, and hence the power/open
protection) had a UL listing standard 20G6 and so there may be something in the difference
between the standards (presumably by some policy, perhaps only one internal to Bell &
Howell about what they'd sell to schools), though my 5 minutes of Googling did not
yield any reference information that relates to what might differentiate those standards.
-Paul