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Posted by Jim Wilkins on January 4, 2011, 6:21 pm
 

I can't find my first one of those, with a home-made wirewrapped
controller board. My Read circuit wasn't reliable enough.

jsw

Posted by Morris Dovey on January 4, 2011, 8:43 pm
 
On 1/4/2011 12:21 PM, Jim Wilkins wrote:

Heh! Some circuits just don't lend themselves to wire-wrapping - but if
you'd like to give it another try, I'd be glad to lend you my old GD
wire-wrap gun. :-)

Reliability might have been improved by adding a bit of solder to each
connection... ;-)

--
Morris Dovey
http://www.iedu.com/DeSoto/
PGP Key ID EBB1E70E


Posted by Josepi on January 4, 2011, 9:44 pm
 I got all set to build my supercomputer with wirewrap methods and then the
0.05" spacing chips came out a squashed that one. Thank God! I knew of a few
that always had crash problems with the wire wrap boards. I don't think
those "up to 2 MHz" signales liked square corners or all those coil
antennae.

Every few years upon cleaning up the house I would run into some old
magazine or news article about the latest and greatest equipment out there.
I remember, once, taking a 10MB (the big old ones about 15" diameter)
harddrive advert for about $0K and sending the article to another guy
hobbying into the PC software, at the time. Annonymously though, just for
the laugh. It didn't take him long to figure who did it and the envelope
came back with an advert for about 8K of core memory for umteen thousands of
dollars....LOL




Heh! Some circuits just don't lend themselves to wire-wrapping - but if
you'd like to give it another try, I'd be glad to lend you my old GD
wire-wrap gun. :-)

Reliability might have been improved by adding a bit of solder to each
connection... ;-)

--
Morris Dovey
http://www.iedu.com/DeSoto/
PGP Key ID EBB1E70E




Posted by Morris Dovey on January 4, 2011, 11:01 pm
 On 1/4/2011 3:44 PM, Josepi wrote:


I designed and built one (only, ever!) computer on an Augat wire wrap
panel and managed to drive it at 20MHz - but wrapped connections are
(IMO) only good for prototyping. The panel had gold-plated
phosphor-bronze pins, but high-quality 30ga wrap wire is silver plated -
it makes good contact at the pin corners, but just a litle bit of
oxidation goes a long way...

...I wasn't joking about adding a bit of solder (after debugging, of
course).


Then you'd probably get a kick out of knowing that I went out and bought
a pair of IBM 2311 (~7MB/pack) drives and a friend at IBM helped me
design an interface for my (then) new IMSAI-8080. After haggling with a
surplus equipment dealer for an entire afternoon, I got the pair of
drives for $200 - which was less than the then-current price for a pair
of 8" floppy drives in a dual enclosure.

A couple of years later Morrow came out with their MD11, a Z80-based
brick with a 10MB HD. I think I still have that packed away somewhere.

--
Morris Dovey
http://www.iedu.com/DeSoto/
PGP Key ID EBB1E70E


Posted by Jim Wilkins on January 4, 2011, 11:41 pm
 
I got good performance with clean signal edges at up to 10 MHz with a
WSU-30M "Modified" hand wrap tool, which doesn't wind the insulation
around the post for strain relief and let me wind in either direction
to avoid pulling the wire tight against the adjacent pin. I attached
the sockets to the board with soldered bypass caps, wrapped the power
with 24 AWG wire, then soldered it.

Signal connection problems disappeared after I asked the cleaning crew
not to use ammoniated products. The diazo room was well vented.

When I had to fix older boards where someone had used tinned sockets I
soldered only the tip of the wrap, so it could be cut short and
unwrapped.

jsw

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