From Louis Ohland@21:1/5 to All on Thu Nov 11 08:11:47 2021
Additional Adapter Signal
The adapter provides one additional signal for use with World Trade
modems, the ‘connect-data-set-to-line’ (CDSTL) signal (connect to
DCE).
This signal is not standardized by EIA RS-232C Specifications. CDSTL
is normally used with World Trade modems (CCITT 108.1). This
signal is used the same as the DTR uses the same pin (pin-20) as DTR.
The On condition causes the data communications equipment (DCE)
to connect the modem to the line. The Off condition causes the DCE
to remove the modem from the line.
From Louis Ohland@21:1/5 to All on Thu Nov 11 08:17:11 2021
Page 83 physical
- 8255 -
380/3A0 Port A Select
381/3A1 Port B Select
382/3A2 Port C Select
383/3A3 Mode Select
- 8254 -
384/3A4 Counter 0 Select
385/3A5 Counter 1 Select
386/3A6 Counter 2 Select
387/3A7 Control Word
- 8273 -
388/3A8 Out Command/In Status
389/3A9 Out Parameter/In Result Register
38A/3AA Out Test Mode/In Transmit I/R
38B/3AB In Receive I/R
38C/3AC Out Data/In Data
Synchronous data link control (SDLC). HDLC was derived from SDLC, which
was developed by IBM in the early 1970s. IBM had submitted SDLC to the
ISO for acceptance. ISO modified it and renamed it HDLC. Effectively,
SDLC is IBM's equivalent to HDLC. (If you sit on the other side of the
fence, HDLC is the ISO's equivalent to SDLC.) SDLC is part of IBM's SNA
and was commonly used in IBM terminal-to-computer communications.
From Louis Ohland@21:1/5 to Louis Ohland on Fri Nov 12 08:37:25 2021
Others posted erudite reasons, but "packets" brought it all together...
Trying to put a serial stream on a network vs a packet... To me, a
packet allows a more deterministic approach, where the traffic is
packets with a known size...