[GreenKeys] M32 Answer back coding...

[Kenneth Gartland]

Hi all!

Firstly, congrats to our newest i-Telex "Kids"
on the block, namely Paul & Jack!

It is so encouraging to see new installs
added to the subscriber base in North America...

Answer back drums are hard to find these
days, used to see the odd one pop up
on eBay, but not for a very long time...

The following info, I hope will clarify the
coding issue for the A/B drums...

There used to be several commercial  coding
"Standards" employed by various commn's
carriers, none of which apply to us now...

We used to use the following coding practice
during the later days of Telex:

Lttrs
CR
LF
(Followed by "Fill" characters [Lttrs] if there are any
uneeded characters in the message body)
Message body
CR
LF
Lttrs

The answer back drum can contain up to
a total of 20 characters, including all
functions...

Usually, there are about 14 characters to play
with for the message body...

Tine "Broken out" is a mark, left in, a space...

Holding and looking at the drum with the
row numbers facing left, the coding count
from left to right for each row is as follows:

code levels

1, 2, 3, 4, the 5th bit uses the tine in the 6th position,
the one in the right hand side of the drum to
the right of the "Print suppression" tine...

Remember, these drums are also used in M33 units,
so there are unused tines which are not needed
for Baudot coding...

In the "ST" row, it is recommended practice
to remove the tine in the "Print suppression"
row, this is needed to avoid a false "Blank" being sent
to line during the ansback start up....

It is also not recommended to "Correct" a coding
error, by breaking out the PS tine, as again it can
send a blank, which mite cause a line disconnect!

Any coding errors, hopefully none, are "Fixed"
by converting the errored character to an
all marking one (Lttrs)...

This only works if you have one or more "Fill"
characters to spare, if not, you have to live
with your​ handiwork...

Here is an old guys coding "Tip"

Write down the entire coding sequence, including
all functions spaces etc., to a max of 20
characters...

If you have any extra "Fill" characters, designate
their coding at the beginning of the coding
sequence following the Lttrs, CR, LF...

When done, here is the "Tip"...

Code the drum in the "Reverse" order from character
row 20 to row 1, in other words you will be
working backards from the end of the sequence
to the beginning...

By doing this, if you make an error, you can correct
the mistake with a lttrs, and move on, providing you
have at least one "Spare" fill character to use...

If you decide to code starting in row 1, and have
coded all your "Fill" characters, and then make
a coding error, your done son!

There is no fixing it then!

I wud suggest to anyone, when composing
your coding sequence to leave at least one
spare "Fill" character at the beginning to work
with, just in case!

P.S. Answerback drum, part# 180827, will already
have the "Print suppression" tine broken out of
the "ST" row...

If you have a Model 33 drum, part# 184149,
it will have the tine in place in the ST row,
and you will have to remove it before proceeding...

That's all for now folks, hope this has clarified
some of the coding confusion...

Cheers!

Ken
VE3-HMQ
i-Telex 61663
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