Re: TK Added Value Items

On 4/22/2010 11:04 AM, halfmeg wrote:
> The latest of those is a 7171 communications controller which it seems
> would allow ASCII terminals to connect instead of requiring a 3270
> client. Anyone know about that device and what it would take to implement?

Unless I have my numbers mixed up, the 7171 was IBM's version of 
a protocol converter. To the system it looks like a 3270 
controller, while the other end provides asynchronous RS-232 
connectors usable for direct connect with a null modem, or via 
dial-up using any standard modem (1200-9600 bps). The converter 
I used was a box from Renex (first TM-1, later TM-3) that was 
essentially similar. My 3174-1L has an Asynchronous Emulation 
Adapter (AEA feature) that does the same thing.

It required configuration to determine the user's terminal type 
(e.g., by line group), or by control character. Once that and 
the speed were negotiated, the device buffers user input until 
an attention generating key was pressed. Output to the terminal 
was converted from 3270 protocol to control sequences understood 
by the terminal. Supported devices included VT-100+, VT-102 
family (with line addressing as a minimum), Wyse-50 (my 
favorite), and similar ASCII oriented CRTs.

Many of these terminals also had a provision for plugging in a 
printer (serial, mostly), and a control sequence that caused a 
pass-through. I used this to print quick short memos that 
otherwise would have been delayed on the mainframe.

Gerhard Postpischil
Bradford, VT