[GreenKeys] physical tape format question

[Don Robert House]

Jim,

I was told that paper strength was the reason for the advance feed  
holes.
Supposedly moving the feed hole on 6 level tape makes it less apt to  
tear
and cause a misread of one of the two closest codes next to the feed  
hole.

In our district we only had two teletypesetting arrangements using  
specially
produced Type 2 Dataspeed Receivers stored by and delivered by the
Associated Press.  As you have stated below only a small adjustment is
required for the reader.

As luck would have it I was given the job of designing the last Type 2
installation at Paddock Publications (now the Herald) in Arlington Hts.
Illinois when I was in the circuit provisioning center.  Somewhere here
I have a copy of my design.  The AP machines were interesting as
they came with a special controller with options for different types of
news.

The most fun however was the Type 4 & 5 with discrete coding
and error detection and correction, but that is another story.

Don
K9TTY

On 9 Mar 2010, at 11:50 AM, Jim Haynes wrote:

It's a fine question, and an interesting one.

The hole spacing is the same for tapes from 5 to 8 level: 10 per inch.
However 6-level is funny in one respect.  In all the others the center
line through the feed holes is also the center line through the code
holes.  But in 6-level the leading edge of the feed holes lines
up with the leading edge of the code holes, so the centers are not
in line.  This is called "advanced feed holes".  But usually tolerances
are such that you can read 6-level advanced feed hole tape on an
inline-feed-hole reader, and 6-level tape punched with inline feed
holes may be perfectly readable on a reader designed for advanced
feed holes.  In fact it should not be hard to adjust a reader to
expect advanced feed holes.  What's hard is punching them, since
if all the punches are in the same punch block you need a special
punch block.  I guess there is some equipment that punches the feed
holes separately; and that would allow adjustment to either standard.

I have no idea why it was done this way - it just was.



jhhaynes at earthlink dot net

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