Re: PC connection via twinax ?

Doug,

Thanks for the info.

My question on twinax I guess approaches the hardware level.

If a 3rd party dev wanted to enable your interactive pgm to write direct to a 
twinax terminal, bypassing a dspf and cfint:  is the twinax interface 
documented to enable this?

Admittedly this is a bit far out there in "why would you want to do that" 
territory, but a valid response is: what is gained by ibm in not releasing what 
I have described.  It is not a threat to system integrity.

also, maybe there could be more twinax type attachments. Any use for a cd r/w 
device attached thru twinax and controlled by a user written rpg pgm?  Or fax 
modem?

-Steve

---------- Original Message ----------------------------------
From: Douglas Handy <dhandy1@bellsouth.net>
Reply-To: midrange-l@midrange.com
Date: Fri, 17 Aug 2001 17:38:44 -0400

>Steve,
>
>Can't address the other issues, but
>
>>Back in the day when converting from the s36 to 400, there 
>>was an ibm product that allowed data transfer thru the twinax 
>>port.  Is it known how to do that?
>
>I believe it was the same way that some early 3x to PC data transfers worked.
>Ignore for a minute complications with characters below EBCDIC x'40'.  Create a
>display format with a single input field starting at 2,1 and continuing to the
>end of the display.  The old DOS based emulators, even IBM very first one,
>included a set of APIs to let a PC program examine or change screen contents,
>simulate keypresses, etc.
>
>To transfer to the PC, the 3x fills the buffer and display the screen format.
>The PC extracts the data out of the emulation buffer and "presses" Enter,
>allowing the 3x to fill it with the next screen of data.  
>
>To transfer to the 3x, the reverse is done.  The 3x displays an empty screen.
>The PC fills the buffer and "presses" Enter.  The 3x collects the data and
>redisplays a blank screen.  The PC "presses" Cmd7 or whatever when done.
>
>Control characters can be handled by a temporary escape to hexadecimal.  Later
>the 5250 protocol was enhanced (and documented publicly) to add a 
>"transparency"
>subcommand to allow "data" to include characters below x'40' .  Using a 24x80
>session you could do up to 1919 characters at a time; using a 27x132 you could
>do 3563 and get better performance.
>
>Back on the 36, I used to write programs for specialized bi-directional data
>transfers using these techniques.  There were third-party tape drives for the 
>36
>which worked in the same fashion -- they would attach as a 3180 via twinax and
>emulate a 27x132 session.
>
>I used one of the boxes you referred to in a 36 to 400 conversion.  It attached
>to both WS controllers, and you could have sessions on each and hot key between
>them.  For data transfers, it would take as many twinax addresses as you would
>allow.  The doc recommended configuring data transfer addresses as 27x132
>displays to maximum throughput.  So I'm pretty sure it worked the same way as
>the old APIs for the emulator.
>
>No undocumented stuff needed for the transfers.
>
>Doug
>
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