On 13 Nov 2004 05:59:06 -0500, james <james(a)jdfogg.com> wrote: I have been away for a time, and am just checking my backlog. I used to work with 3270-emulation and compatible hardware. Old 3270 controllers did not use SDLC, they were running Basic Mode aka binary syncroneous. SDLC was an option which came later. This is a synchroneous protocol without bit stuffing, to obtain binary transparency octets which were identical to control codes had to be escaped. IBM 3270 used the EBCDIC control codes for their documented purpose. HP 2645 terminals had an option to run multidropped using an almost identical protocol. This protocol is half duplex. The coax is used to connect the controller to the terminals. The controller was connected by modem to the host at speeds up to 19200 bits/s, and controlled a cluster of terminals. The coax protocol was similar, but used some type of manchester encoding at around 500 kilobaud. I think Orchid made a PC card with the 3270 coax connector. I believe I have one hidden away somewhere in my collection. -- Using Opera's revolutionary e-mail client: http://www.opera.com/m2/

On Sat, 2004-12-04 at 16:13, Paul Koning wrote: The simplest protocol has to be Burroughs Standard Poll Select. Imagine daisy-chained RS232 and a polling sync or async protcol using ascii control characters/words. I did lots of conversions to frame relay using Motorola routers with Poll Select.