Re: 5251/Twin-Ax terminal emulation

[Jerry Draper <midrangel@xxxxxxxxxxxxx>]

I have to say the USB twinax that TwinData sells are super easy to 
install/use.

Jerry

On 12/3/2019 9:27 AM, Jason Olson wrote:
> Personally I don't know why you would go through all this effort. It's
> pretty easy to pick up some 5250 ISA and PCI cards off eBay, and connect to
> an older system that way. I still have a few terminals at home that I use,
> but I also have a 5250 PCMCIA card in my IBM T60 Thinkpad that I use the
> most. I was able to grab 4 of these off eBay about 10 years ago.
>
> So besides the technical hey I did this kinda thing, what are you trying to
> accomplish here?
>
>
> Thanks,
>
> Jason E. Olson
> IBM i Engineer/Developer
> josys36@xxxxxxxxx
> 480.223.2952
>
>
> On Mon, Dec 2, 2019 at 9:33 AM <alan@xxxxxxxxxxx> wrote:
>
> > All,
> >
> > I've built a line-sniffer for my mid-80s System/36 (5362) in an attempt
> > to fully understand the TwinAx electrical and protocol layers.  The long
> > term goal is to build an affordable open-source terminal emulator
> > providing either a TN5250 bridge to emulated TwinAx terminal sessions or
> > a more simple telnet/ASCII/vt10x translation on a series of TCP ports by
> > a WiFi ESP32.  twindata.com offers a lot of similar products but they
> > are closed-source and far outside of the price range of most retro
> > computing enthusiasts.  There doesn't appear to be a lot of people
> > running older System/32, S/34, S/38 and gen-1 AS/400s.  But the keyboard
> > pirates are slowly destroying older terminals and I want the surviving
> > machines to be easy to interface to so they can be as usable as
> > possible.
> >
> > I've worked through all the electrical and framing issues and annotated
> > a few dumps of the S/36 IPL with both an InfoWindow II and 3179
> > attached.  The output of which can be found here:
> >
> > https://www.retrotronics.org/tmp/s36_ipl_decodes1_01dec19.zip
> >
> > The message structure and limited command descriptions came from this
> > document starting on PDF page 122 / printed page number 4-9:
> >
> >
> > http://bitsavers.trailing-edge.com/pdf/ibm/5250_5251/SY31-0461-0_5251_Display_Station_Model_11_Maintenance_Information_Dec77.pdf
> >
> >
> > However it is incomplete.  Not all commands are enumerated, the modifier
> > address bits are not explained (addresses a LU inside the terminal), and
> > none of the context or arguments for the commands are elaborated on.  A
> > simple example of what I am referring to is, for example, the
> > explanation of the argument bits for the SET MODE command, etc.
> >
> > Can anyone point me to a document or resource that fully explains the
> > TwinAx 5251 model 12 display protocol?  I've been searching for days now
> > and no luck.  And I really can't make anymore progress until I'm
> > unblocked by documentation.  I simply don't have enough time to
> > trial-and-error reverse engineer bit meanings.
> >
> > Thanks,
> >
> > Alan Hightower
> > --
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