BiSync was designed long before packet
switching networks were envisaged, therefore extra protocols are
required to carry it across PSS:
Host Terminal
Protocll PSS Protocol
Convertor ............... Convertor
Host ---------- . . ---------
Computer | | . . | | 3270
------- | | . . | | ---------
| | | | . . | | | |
| | | | . . | | | |
|HOST +-| PAD +----. PACKET .-----| PAD +---| CU |
| | | | . SWITCHING . | | | |
+-------| +----------| ................. +---------| +---------|
|
| --
+-| \--
| +-----|
| --
+-| \--
| +-----|
| --
+-| \--
+-----|
<---------------- 3270 data stream ------------------------>
<----DSP -------------------------->
<-- BSC ---><----X.25 -------------------------><-- BSC -->
I have further information on the following,
IBM-BSC.TXT Binary Synchronous Communications
IBM-DSP.TXT Display System Protocol
IBM-DS.TXT 3270 Datastream