From: whit@carson.u.washington.edu (John Whitmore)
Subject: Re: Wire wrap questions (again?)
Article-I.D.: shelley.1pr803INNh8e
Organization: University of Washington, Seattle
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In article <PASCAL.93Apr1160623@ap10.apd.cpg.sony.co.jp> pascal@apd.cpg.sony.co.jp (Pascal Goguey) writes:
>In article <7376@blue.cis.pitt.edu> macfitz+@pitt.edu (Mark D Fitzsimmos) writes:

> *After a considerable amount of research, review of discussions 
> *on this group, and mainly fruitless time on breadboards, I have 
> *decided that the path of least resistance for prototyping my (not 
> *necessarily someone else's) electronic designs is wire wrapping.  

>	I have no idea about what you want to do, but be careful :
>Wire wrapping increases a lot the wiring capacitance. That shouldn't
>be a problem for "slow" applications (i.e a few MHz), but as for
>quicker ones (around 30 / 40 MHz), I doubt that it can work.


	Fortunately, wire-wrapping is a better wiring technique than
most at high frequencies; Cray computers (up to the X-MP, at least)
all had wirewrapped backplanes.  Wirewrap gets into trouble at
much higher frequencies than any TTL can handle.  The 'increase'
of wiring capacitance is not really relevant (you have to use
transmission line techniques, and the capacitance is no problem).

> *1) Where can I get a decent wrapping tool?  I'd like to spend less 
> *than $150 for an AC powered unit including bit and sleeve.

>	Hand powered is the best. There are good AC powered ones,
>but rather expensive. A low-cost one doesn't work very well.

	Hand-powered is a terrible choice (IMHO) unless you are
a field maintenance person who will do maybe a dozen connections
at a time.  Your hands will cramp.  Battery-powered wire-wrap guns
are available in the $150 range, and so are the little
twiddle-stick manual types ($15).  For a modest project, of
a couple hundred connections, I'd prefer to borrow a professional
AC unit... or a pneumatic one.

	John Whitmore
