If you want to find out what that would be like, hunt down a copy of
TNVT100, written by Arty Ecock at CUNY. It does VT100 emulation on a
3270. 

You won't like the results. Vi, etc are just too character-oriented to
work well on a 3270, and the amount of refreshes, etc necessary to get
output to the 3270 and flush input to the converter is enormously
inefficient. 

The fundamental problem is really that curses doesn't understand
block-mode terminals, and doesn't keep enough state in the terminal
handler to keep track of the blocks. If it did, then this wouldn't
really be an issue, and we could easily define a 3270 terminal in
terminfo and it would Just Work. 

Even HP/UX doesn't handle this well (and AFAIK, they're the only ones
who still *make* block-mode ASCII terminals), and even they recommend
not running them in block mode if you can avoid it (only useful on low
bandwidth, very high latency links, like direct VSAT links from the US
to Australia or such). 

David Boyes
Sine Nomine Associates

> -----Original Message-----
> From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of
> McKown, John
> Sent: Monday, August 14, 2006 12:16 PM
> To: [email protected]
> Subject: protocol converter?
> 
> I've read a lot here about people wanting to use vi or some other
> application which is "full screen" from the "Linux console". The reply
> is always that the "Linux console" cannot be used in the manner. Now,
> back in the deep, dark past, I remember a product that we had on
VM/370
> (yes, that long ago!). This was a software protocol converter which
> allowed a "start-stop" or async terminal, such as a VT-100, to logon
to
> a service machine (via NCP/NTO). This service machine would then use
> VM's LDC (?) to create a 3270 session and it would convert the 3270
> control sequences to VT-100 control sequences.
> 
> I'm curious if something similar could be done for Linux. That is,
have
> the "Linux console" be defined as CONMODE 3270 in the guest's VM
> directory. Now, have a "device driver" which could do a reverse 3270
> protocol conversion. That is, make the 3270 appear as a VT-100 (or
> subset). The application would use VT-100 escape sequences. The device
> driver would convert these to 3270.
> I will grant that emulating the "full duplex" ability of the VT-100
and
> "control keys" would make this difficult. But z/OS DIDOCS emulates a
> "full duplex" capability on a 3270, so it should be possible. Well, to
> those who are smart enuf (I'm not!).

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