[GreenKeys] Digitronics Dial-o-verter in Transatlantic Teleteypsetter Link

[David I. Emery]

On Mon, Jul 09, 2012 at 01:31:59AM -0500, Jeffrey D Angus wrote:
> On 7/9/2012 1:30 AM, dmm at lemur.com wrote:
> > Digitronics "Dial-o-verter" modem
> 1000 word per minute. Amazingly fast.
> Well roughly 670 baud. But still. ;-)
> 
> Not too shabby for 1960 technology.
> A little more fiddling with numbers and....
> Given 0.10 inch per row of punched holes,
> that's roughly 111 rows/second or about
> 1 ft/sec or 60 ft/minute tape speeds.
> 
> Yahoo. Be that was a real mess at the far
> side of the tape reader if a reel jammed.

	Those of us of what for women is called a "certain age" (aka old
phartes) may remember this well, as there was an era in the development
of computers when minicomputers used and read paper or later mylar tape
to load programs and data.   So for that matter did a variety of other
things common in that era, ranging from missile guidance systems to
crypto key loaders... and lots and lots of numerically controlled
machinery such as numerically controlled milling machines and circuit
board drill systems.

	Needless to say producing all that punched tape efficiently
required high speed punches, some of which certainly could go much
faster than even 100 rows a second.   Relying on 10 character a second
Teletype gear to punch the quantities and lengths of tapes involved
would have taken absolutely forever...

	And myriads and myriads (in the minicomputer world especially)
of high speed photoelectric readers... to read all those tapes in finite
time.

	Both made tape fly past punches or readers at high speed and
both could and often did make huge messes when the tape jammed.  And
all too often in the ancient minicomputer world the jam would happen
after literally several minutes of reading tape and all too regularly
would destroy the last copy of some program tape one needed, requiring
slow hand patching of the damaged tape with special scotch tape splices
and a complete reread of that and maybe other tapes before one could
get any work done.



-- 
  Dave Emery N1PRE/AE, die at dieconsulting.com  DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in 
celebration of what could have been, but wasn't and is not to be now either."