used as a FEP for mainframe or as a remote switch.
1.1 - Hardware
| 3704 | Smaller version of 3705 - obsolete but still in use. |
| 3705 | Small IBM computer customised for use as a communications controller supporting physical management of the network. Also usable as a remote communications controller or network node in multi-system environments. Control software is NCP for SNA networks and EP for pre SNA networks. |
| 3725 | Enhanced and more powerful version of the 3705 communications processor. release 4 (1986) main storage up to 3 megabytes supports kilostream X.21 |
| 3720 | model 001 - (introduced 1986) small modular, low end version of 3725 |
| 002 | |
| 011 | |
| 012 | |
| 3721 | model 1 - (introduced86) - expansion unit |
| 2 | |
| 3728 | communications control matrix switch |
1.2 - Software
NCP - Network Control Program
SNA program resident in the 37x5 communications processor.
NTO - Network Terminal Option
Protocol convertor for non-SNA data-streams, supports
teletype,3750/1750 PABXs, allows BSC device to run off a NCP
NPSI - NCP Packet Switching Interface
allows connection to X.25 (QLLC)
PCNE - Protocol Convertor for Non-SNA equipment.
EP - emulation program - allows pre-SNA devices
PEP - partitioned emulation program - allows mixture of devices
2780/3780 IBM batch or RJE terminals, now outmoded as hardware
products but whose protocols continue to survive.
Modems
5865 9.6 kbs has CNM=communications Network Management Functions
5866 14.4 kbs
5868 has 2-wire or 4-wire switched network feature
Interfacing to an X.25 network - NPSI
NCP Packet Switching Interface (NPSI) allows SNA to be connected across a
packet switching network.
This software runs with NCP in the front end processor and is a heavy user of
the processor.
NPSI was written under special contract to a French customer and initially the software had the reputation of being unreliable and badly supported.
Release 2 onward of NPSI has packet assembler/disassembler (PAD) support.
Users can also write their own transport service gateways using genralised
access to X.25 transport extension (GATE). This is a module in NSI and communicates
with a special application, known as a communication and transmission control
program (CTCP) which runs on the mainframe using standard facilities provided
by VTAM
Writing transport service gateways
Mainframe FEP
.................. .................
. . . .
. MVS . . NCP .
. | . channel . | . x.25
. VTAM .________________. NPSI .___________________
. . . .
. CTCP ..................... GATE .
.<-sna-> (LU) . . .
. . . .
.................. .................
NPSI integrated PAD
In this mode NPSI handles all X.25 messages incoming X.25 resets and X.29
parameter indications are treated as errors and the call is cleared.
Mainframe FEP
.................. .................
. . . .
. MVS . . NCP .
. | . channel . | . x.25
. TSO VTAM .________________. NPSI .___________________
. . . .
. . . PAD .
. .<--- SNA ------>. (LU) .<---- X.29 ------>
. . . .
.................. .................
NPSI transparent PAD
Mainframe FEP
.................. .................
. . . .
. MVS . . NCP .
. | . channel . | . x.25
. __|_ .________________. NPSI .___________________
. | | . ^ . . remote
. TSO VTAM . | . PAD . start-stop
. . | . .<----- x.29 ------>
. . | . . terminal
.................. | .................
TSO/VTAM defines uses the first byte of
terminal type the buffer to indicate
as user-defined whether it contains
data,qualified data or
X.25 interrupt or reset
Remote 3270 support
Mainframe FEP 3274
.................. ................. ..............
. . . . . .
. MVS . . NCP . . .
. | . channel . | . x.25 . .
. __|_ .________________. NPSI .______. .
. | | . . . . .
. TSO VTAM . . PAD . . .
. . . . ..............
. . . .<-- QLLC --->
.................. .................
<-------------- SNA ------------------------------->
These methods all require the purchase of NPSI, the overheads of running it
in the FEP and mainframe, the effort of re-configuring and the extra operator
involvement in re-establishing X.25 calls should they fail.
For this reason most users currently find it easier + cheaper to use a separate
SNA or BSC PAD if X.25 is used.
mainframe FEP PAD PAD TERMINAL
........ ...... ....... ....... .........
. . . . . . . . . .
. MVS . . . . . X.25 . . . .
. VTAM .___.NCP .___. .______________________. .___. .
. . . . . . . . . .
........ ...... ....... ....... .........
<-chan-><-SDLC-> <-SDLC->
<-------------------------- SNA ---------------------------->
2 - 2780/3780 RJE - remote job entry devices
IBM batch or RJE terminals, now outmoded as hardware products but whose protocols
continue to survive.
3 - 3270 Terminal Control Units
3270 is a generic name for a range of IBM terminal control units and terminals.
Here is some general information on the IBM products. Many other manufacturers
make 3270-compatible devices.
| 3271 | Original 3270 remote cluster controller using BSC line protocol |
| 3272 | Original 3270 local (channel attached) cluster controller. Responds directly to channel commands, and interrupts the channel for attention. |
| 3274 | Range of cluster controller replacing the 3271 and 3272, and capable of emulating both. Available with various amounts of storage, local and remote attachment options. Functions as an SNA PU2, and will also support non-SNA operation. The 3274 has powerful processing capabilities, and will probably take on increased functionality as functionality is distributed from the mainframe into the network. |
| 3274-1A An SNA local control unit in the 3270 family. | |
| 3274-1B A non-SNA local control unit in the 3270 family. | |
| 3274-1D A non-SNA local control unit in the 3270 family. | |
| 3274-51C A 12-port, mini version of the 1C | |
| 3274-61C A 16-port varient of the 51C | |
| 3275 | Remote BSC screen/printer controller with dial-up facilities. Used as specialist device for remote operation of 4300 processors. |
| 3276 | A range of remote BSC/SDLC control units in the 3270 family, each built into a VDU and capable of supporting up to seven more VDUs or printers. |
| 3174 | The long awaited 3274 replacement arrived in 1986. It supports LU6.2 and LAN etc. |
Configuration Support levels
5 configuration support options are currently availible:
A -
C - Extended data stream
D - Distributed Function Terminal (DFT) - allows 4 concurrent host sessions
P - Packet - X.25 support
T - Temporary - to enable customers with 128K control units to try out
the 3290 terminal
3.1 - Multiplexor
3299 Allows up to eight 3270 family devices to share one co-axial cable to
their controller.
configuring 3274
001
1234567890ABCDEF 34
011 <enter>
021 (enter>
031 <enter>
151 <enter> 61c
331 1 sdlc
parameters all entered flashing
disc running v
lights ............................ 1101 <---- insert language
1101 <---- insert system
1111
3.2 - 3270 Terminals
| 3270 | PC - Version of the PC which provides workstation facilities. Can run four 3270 type sessions, two local notepad sessions, and one PC DOS session. The 3270 PC can be a terminal off a control unit but does not directly emulate a control unit. |
| 3270 | PC AT - More powerful version of the 3270 PC. |
| 3277 | Screen (head) for a 3271/3272 controller |
| 3278 | The monochrome screen (head) for the 3274/3276 controller |
| 3279 | Colour screen. Effectively a colour version of the 3278 (replaced by 3179 in 1986) |
| 3178 | A display unit in the 3270 family |
| 3179 | Colour graphics terminal |
| 3290 | Plasma information panel. Large screen (62 x 160 characters), supports multiple applications, graphics etc. |
3.3 - Printers
3262 Small line printer
3268 Small serial printer. Available in monochrome and colour versions.
328x Printers for the 3270 family
Plug Compatables
STC ITT 3820 - Maidstone Road,Sidcup Kent DA14 5HT 01-300 7788
Datatrade 38 Billing Road, Northampton NN1 5DQ 0604 22289
Telex 33 Clarence Street, Stanes, Middlesex TW18 4SY
0784 63891
BT interface to netstream LAN
N74 - interface Netstream <-> 3274 coax
N78 - interface Netstream <-> Terminal/printer
Room 607 Lutyens House 588 3341
4 - Protocol Convertors
An SNA network is based on SDLC which is a synchronous protocol. BI-Sync devices
can be directly connected to a 3705/3725 which does the protocol convertion
to a 3705/3725 which does the protocol convertion. Other devices such as asynchronous
(start/stop) terminals need protocol convertors to connect to an SNA network.
| 5973 | NIA Network Interface Adaptor |
| 3710 | Network controller for concentrating PU2 nodes onto a 3705/3725 with some protocol conversion (up to 31 lines). converts SDLC or X.25 to multiple BSC,ASYNC or SDLC lines. Very powerful hardware which may well replace the 3705/3725 boxes inthe long term, as well as giving birth to a family of products for communications network management. |
IBM offers two protocol convertors to enable stand-alone, start/stop
(asynchronous) terminals to emulate 3270 terminals. They are:
7426 Terminal Interface Unit (TIU)
an eight-port protocol convertor that emulates a 3276 Model 12 SNA
control unit. Two models are available:
Model 1 which attaches to 8100,4321 and 4331 loops
Model 2 which attaches to an ACF/NCP or 8100 SNA/SDLC link.
7171 ASCII device
attachment control unit. This unit was announced in the USA on 10 Sep 1984.
