Re: What are the chances of a Replica II project?

[pausch@saaf.se (Paul Schlyter)]

In article <1153238447.420332.79100@35g2000cwc.googlegroups.com>,
David Schmidt <David4602@gmail.com> wrote:
 
> Paul Schlyter wrote:
>> In article <PZOdnQJ4Uds8jCHZnZ2dnUVZ_rydnZ2d@comcast.com>,
>> Michael J. Mahon <mjmahon@aol.com> wrote:
>>> The Apple II peripheral bus was designed as a leap in expandability
>>> and ease of use.  Truly the first real example of "plug and play".
>>
>> Not quite .... you could not plug in or unplug the cards while the
>> Apple II was powered-up - as you can do with PCMCIA or USB.
> 
> For an interesting counter-example, see:
> http://folklore.org/StoryView.py?story=Scrooge_McDuck.txt
> 
> Quoting Andy Hertzfeld's article:
>> Cliff [Huston] told me [Andy Hertzfeld] that he could insert
>> a disk controller card into Burrell's Apple II with the power
>> still on, without glitching it out, a feat that I thought was
>> miraculous - you'd have to be incredibly quick and steady not
>> to short-circuit any of the contacts while you were inserting
>> it, running the risk of burning out both the Apple II and the
>> card. But Cliff said he'd done it many times before: all that
>> was required was the confidence that you could actually do it.
>> So I crossed my fingers as he approached Burrell's Apple like
>> a samurai warrior, concentrating for a few seconds before
>> holding his breath and slamming the disk card into the slot
>> with a quick, stacatto thrust.
>>
>> I could barely make myself look, but amazingly enough Burrell's
>> machine was still running, and the disk booted up so I could
>> load the Scrooge McDuck image and my new conversion routine.
 
...ok, it *CAN* be done - with special training.  But "hot plugging"
means that the decvice should be insertable, while the unit is
powered, by someone *without* special training.
 
The trick is to make sure the "ground" connection gets connected
first.  Damage to devices is most likely to occur if power, plus
some signals, are connected while the ground is not yet connected.
 
Perhaps that guy have trained to insert the card in such a way to
make the ground connect first?  And then he added some drama to it
of course....
 
In the PCMCIA connector, getting ground connected first is ensured
by making the ground pins (and there are several of them) longer than
the other pins.
 
-- 
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