[GreenKeys] ADP1A1 - A noteworthy date in Bell System and Teletype history

[Don Robert House]

On 31 Aug 2012, at 3:22 AM, Jerry Murphy wrote:

Greenkeyers:

Today is a noteworthy date in (Bell System) Teletype history.  50 years
ago today, on August 31, 1962, 60,000 TWX machines in the US switched
from manual service to dial service. For the subscriber, all that had
to be done was to turn a switch located underneath the 101 data set.
The switch-over was done at the end of the business day. Then as now,
August 31 was the Friday before the Labor Day weekend. The Bell System
gave  themselves the 3 day holiday to work out the inevitable kinks in
the cutover.

Jerry Murphy

THANKS for the reminder Jerry!

This was a huge project that began years before the cutover. 101A & B
type Data Sets had to be installed on each and every machine.
Lots of wiring modifications and the addition of a Subset that looked
like a Telephone, but had no letters on the dial, no switch-hook, and
no transmitter in the handset. This was the modification for the M15
and the M19. Any customers with M14 tape printers on manual TWX were
updated to a M15 or M28 KSRs.

The model 28 KSR was adapted in some cases like the M15 depending on
supplies of the newer dial TWX cabinets that were produced for the M28
line. The newer M28 cabinets were wider and held the call control unit
and the dial built in. Call progress on these models as well as some
early M35 were via a half handset with only the receiver that hung on
the side of the machine. Green for M28 and gray for M35.  Eventually
speakers replaced the half handsets.

Over time we removed the cutover switches when we were routining the
machines. Most of them kept the yellow instruction labels on the inside
of the covers. Some techs screwed a guard over the switch handle so
that the cutover switch could not be operated.

One of the next big projects was to build a completely separate network
for dial TWX and convertor locations in major switching centers so that
ASCII machines could "talk" to Baudot machines at different speeds. All
5 level machines remained at 45.5 Baud and all ASCII machines ran at
110 Baud. A restraint signal was sent from the convertor to the ASCII
machine to stop the transmitter until the Baudot machine could "catch
up." That is the orange lamp on the M33 and M35 labeled "REST."  Many
operators thought the machine had to rest in between long tape
transmissions!

Additional plans were in the works for Wide Area Data Service (WADS)
and an updated call controller so that lamps would indicate call
progress and connection status. This was scrapped when the Justice
Department ruled that the Bell System had to sell all of our TWX
network to Western Union.  Some of the M33 and M35 machines retained
the lamp bezels on the call control unit that were intended for use
with the WADS-D controller.

Memories,

Don K9TTY
Ye old Teletype Communications Serviceman