[GreenKeys] Model 28 ASR

[jhhaynes at earthlink.net]

On Thu, 14 Apr 2005 Commtekman at aol.com wrote:

> My question today is: I have a 28  
> ASR with what appears to be a printing reperforator in the upper left hand  
> corner, and a printing perforator next to the tape reader. Since I am new to  
> this, is this a normal configuration? I apologize for the ignorance.
> Bob K6OSM

Yes, that's a normal configuration in the zoo of Model 28 equipment.

There are historically two "architectures" of ASR sets.  
The one used in Europe for many years, and introduced into the U.S. with
the Model 32/33 line, has the tape punch sharing some parts with the
printer and the tape reader sharing some parts with the keyboard.  Hence
you can punch a tape of whatever you are printing, and you can send a
tape as an alternative to keyboarding.  To punch a tape from the keyboard
you have to take the machine offline (unless you want to transmit at the 
same time you are punching) and you always get printer copy of what you 
are punching.  You can't punch tape "blind" while you are receiving
from something else, and you can't punch tape while you are using the
tape reader to send.

The other architecture, used in the Model 19 and carried over to the
28 and 35, is that the punch shares some parts with the keyboard and
the tape reader is separate.  You can take the machine offline and
punch tape while getting printer copy of what you are punching.  You
can also be receiving printed copy from the line while punching tape
blind from the keyboard.  And you can transmit from tape while you
are punching more tape with or without using the printer for copy of
what you are punching.  But you can't punch a copy of what you are
receiving unless you have an auxiliary reperforator, because the punch
isn't connected to anything but the keyboard.  So that is why an option
for the 28ASR is a reperforator under the dome; and for the Model 19
it sits on a stool under the table or on a platform above the table.

The original standard keyboard perforator on the 28ASR is a non-typing
punch mechanically connected to the keyboard.  It can't punch anything
but what comes from the keys, just like in the Model 19.  And if you put
the switch in the T position you can punch as fast as you can type,
independent of the speed of the printer and reader.  But the 28 line
was pretty versatile, so you could substitute a reperforator for the
punch if you wanted to. In the 35 I don't believe they bothered making
a perforator only and just used a reperforator because the machines
all ran at 100wpm anyway and that was about as fast as anybody could
work the keyboard.  And you could have a typing reperforator next to
the keyboard if you needed to see what was punched into the tape.

The 28ASR allowed several kinds of tape readers: LXD is a simple
single-contact reader.  LAXD is a crawling head reader (can read
right up to the last character punched) and has a separate transmitting
distributor.  LBXD is a fixed-head reader with separate transmitting
distributor.  You could have two readers.  And there was the LFXD
which read five-level code punched into one-inch tape and could read
forward and backward and punch extra holes in the edges of the tape.

So what you have is a "normal" ASR set with the capability of punching
a copy of what you are receiving on the under-dome reperf, and of punching
from the keyboard while you are receiving.


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jhhaynes at earthlink dot net