Telecommunications - Bi Sync Protocol - 3270 datastream

3270 is a generic name for a range of display products first announced by IBM in 1971. 3270 data stream is the protocol used between the display system control unit and a host computer, it is independent of the line protocol and so can be carried over a BSC link or a SNA network. The 3270 data stream has control codes embedded in it to format the data and control text going from the host computer to the 3270 screen and text read from the 3270 keyboard to the host computer. An extended data stream was defined in 1979 to support additional features such as colour.

 



1 - BSC 3270 related protocols



Host Terminal

Protocol 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

IBM-SNA.TXT Systems network Architecture

IBM-GTE.TXT Telenet 3010 PAD

IBM-PAR.TXT Telenet 3010 Parameters

IBM-TRI.TXT Information on the 3270 BSC Trial

IBM-PLAN.TXT Information on BT use of IBM protocols

2 - 3270 DATA STREAM - INTRODUCTION

`3270 Data Stream' is the term used to describe the device control protocol usd between an IBM host computer and an IBM 3270 control unit - (3271, 3272, 3274, 3275 or 3276) - to exchange user or control data, to or from displays or printer attached to the control unit, and application programs executing in the host. 3270 Data Stream consists of user data, commands to initiate data transfer operations, orders to `control' and modify the representation of the data, a buffer addressing scheme to denote the location of user and control data within the display or printer presentation space and control fields to convey control or status information.

3270 Data Stream is data-link protocol independent, ie the same data stream is used by local (channel attached) and remote (SDLC or BSC, line attached) control units, and it supports both EBCDIC and ASCII character coding schemes.

3270 Data Stream does not deal with link-level control unit addressing of displays and printers relative to a control unit. This addressing is performed by a combination of SNA addressing and data-link control protocol-defined addressing schemes:

3270 Data Stream can be divided into four categories:

The standard Data Stream is sometimes referred to as Base Data stream, while Extended Data Stream is sometimes referred to as ructured-field Data Stream.)

-------------- ----------------- coaxial --

| | outbound data | | cable | \-

| | -- stream ----> | |==========+----|

| | | | display

| +------------------| |

| | Link | | coaxial --

| | | | cable -| +-

| | inbound data | |===========+------|

| | <-- stream ---- | | printer

+--------------| +-----------------|




(ASCII character codes are not supported by the Extended Data Stream.)

3 - Fields

3270 datastream is based on the concept of fields. A formatted screen is organized into fields by the application program. The 3270 datastream defines 3 types of attributes for these fields as follows:

Field Attributes Extended Field Attributes Character Attributes
Protected or Field validation Extended highlighting
unprotected
Extended highlighting Colour
Alphanumeric or
numeric Colour Character set
Autoskip Character set
Nondisplay or Field outlining
display/intensified
display
Detectable or
nondetectable

A field consists of the field attribute character and all the data following it up to (but not including) the next field attribute. A field can wrap from the end of one row to the beginning of the next row within the presentation space. A field can also wrap from the last location in the presentation space to the first location. There is no limit to the number of fields that can be defined, other than that imposed by the screen size.

Screen

---------------------------------------

| - |

| |A|Text ...|A| |

- . -

| . . |

| . . |

+----.------.---------------------------|

. ...............................

. .

Field Attribute .

---------------

takes one character position .

displayed as a space .

. .

. .

Extended field attribute Extended character atribute
always associated with a extra information associated
field attribute but does with a character on the screen
not take up extra space but does not take up space in
in screen memory screen memory

4 - Buffer Addressing

3270 Data stream currently caters for six different display buffer sizes:

480 characters (12 rows of 40 characters)

960 characters (12 rows of 80 characters)

1920 characters (24 rows of 80 characters)

2560 characters (32 rows of 80 characters)

3440 characters (43 rows of 80 characters)

3564 characters (27 rows of 132 characters)

Two buffer addressing schemes are available, both of which use two

characters to specify a given buffer location.

12-bit buffer addressing - used with:

outbound & inbound Standard data stream

inbound Extended data stream

outbound Extended data stream

Absolute position = (row number - 1)*presentation space

width + (column number-1)

first address character = Absolute position DIV 64

second address character = Absolute position REM 64

14-bit buffer addressing - only used with:

outbound data stream to control units which

support extended data stream

Absolute position = (row number - 1)*presentation space

width + (column number-1)

prefix with leading zero bits to give 16-bits

5 - Extended data stream

PARTITIONS

If the display supports partitioning, the application program can define a logical area called a partition that may differ in both size and shape from the physical display screen. The partition is defined by use of the create partition structured field. Once a partition has been created, data is transmitted to and from the partition as if it were a physical screen with the geometrical characteristics specified in the create partition structured field. The mapping of the presentation space to the physical screen is transparent to the application program. The initial state of a display supporting partitions is the implicit partition state, interaction with implicit partition 0 on a display that does not support partitioning.

Programmed Symbols

A programmed symbol (PS) is a special character or graphic component that is loaded by the application program into a symbol set in the device. Each symbol set contains 190 symbol locations; each location contains a pattern of binary bits equivalent to the dot pattern contained in each character position on the display screen

Triple-plane symbol sets

In certain applications it may be necessary to display more than one colour within a single character position. The programmed symbols feature allows the user to define symbols that contain more than one colour, these symbols are stored in a triple-plane symbol set.

6 - 3270 Outbound Data Stream (host to terminal)

Outbound data stream | Inbound data stream

(from host to terminal) | (from terminal to host)

------------------------+---------------------------

| |

S E S CU CU

T S command T add add text...

X C X see inbound

| data stream

------+-----------

| --+----------------------------------------

F3 structured | F1 Write | |

field | F5 Erase/Write | |

| | 7E Erase/Write alternate | |

v | F2 Read Buffer | WCC | text

see outbound | F6 Read Modified | | stream...

structured | 6E Read modified all | |

field | 6F Erase all unprotected | |

+---------------------------+--------+------

------------------------------| |

| |

----------------+---------------- |

| bit0 - reset function | |

| bit1 - 0=partition characters | |

| remain unchanged | |

| - 1=partition characters | |

| to defaults | |

| bit2 - reserved | |

| bit3 - reserved | |

| bit4 - start printer bit | |

| bit5 - sound alarm bit | |

| bit6 - keyboard restore bit | |

| bit7 - reset modified data tag | |

| (MDT) | |

+---------------------------------| |

v

7 - Outbound text stream

Orders embedded into text string:

Order EBCDIC ASCII
Start Field (SF) X'1D' X'1D' field attribute data..
Start Field Extended (SFE) X'29' N/A number of attribute attribute
type-value type type
pairs
Set Buffer Address (SBA) X'11' X'11' buffer address (2 bytes)
Set attribute (SA) X'28' N/A attribute attribute
type value
Modify Field (MF) X'2C' N/A number of attribute attribute
type-value type type
pairs
Insert Cursor (IC) X'13' X'13'
Program Tab (PT) X'05' X'09'
Repeat to address (RA) X'3C' X'14' stop address(2-bytes),character
Erase unprotected to address (EUA) X'12' X'12' stop address(2-bytes)
Graphic escape (GE) X'08' N/A character code

8 - field attribute character

The attribute character takes the space of one character in the display

buffer and is displayed as a blank, it is sent in the outbound datastream

as follows:

-----------------------------------------------

| Start Field | field attribute | data ...

| SF=hex '1D' | character |

---+-------------+-----------------+----------

|

v

-------------------------------

| 0 1 | 2 | 3 | 4 5 | 6 | 7 |

-------------------------------

| | | | | |

| | | | | +------------ Modified Data Tag (MDT)

| | | | | this bit is used to designate

| | | | +-- Reserved fields that have been modified

| | | | by the display operator

| | | +- presentation mode (data entered or contents

| | | 00=Display selector- overwritten)

| | | pen non-detectable 0=not modified

| | | 01=Display selector- 1=modified (an application

| | | pen detectable program can set this bit on

| | | 10=High-intensity when inserting the attribute

| | | display selector- character to ensure that the

| | | pen detectable field is treated as a modified

| | | 11=Non-display, field during read operations,

| | | selector-pen irrespective of operator

| | | non-detectable action)

| | | (non-printable)

| | |

| | +----- Alphanumeric/numeric

| | 0=alphanumeric

| | 1=numeric

| |

| +--------- Protected/unprotected

| 0=unprotected

| 1=protected

|

+--------------- Reserved

contents depend on settings of bits 2 to 7

(qv internal six-bit code structure)

the 3279 uses the field attributes for the additional purpose of

controlling colour, this depends on the setting of the base colour switch

as follows,

Field attribute attribute bit base colour switch
2 3 4 5 oo oooo
unprotected, normal intensity 0 x 0 x green green
unprotected, intensified 0 x 1 0 white red
protected, normal intensity 1 x 0 x green blue
protected, intensified 1 x 1 0 white white

9 - Extended Field Attributes:

Start field number of Attribute Type Attribute Value
Extended type-value
SFE=hex'29' pairs

To set Character Attributes:

Set attribute Attribute Type Attribute Value
SA=hex'28'

EXTENDED ATTRIBUTE TYPES

Type Value may define
Extended Character
Field attribute
Attribute
00 attribute types 00 reset all attribute types N/A YES
C0 field attribute bit pattern as for AID YES N/A
C1 Field validation bit 0-4=0 YES N/A
bit 5=mandatory fill
bit 6=mandatory entry
bit 7=trigger
C2 Field outlining bit 0=underline YES N/A
bit 1=right vertical line
bit 2=overline
bit 3=left vertical line
41 Highlighting 00=default YES YES
F0=normal- as defined by field attribute
F1=blink
F2=reverse vidio
F4=underscore
42 colour 00=default colour YES YES
F7=neutral
others=as indicated by query reply
on 3279 models 2B and 3B attached
to a 3274 these are as follows
F1=blue F2=red
F3=pin F4=green
F5=turquoise F6=yellow
F7=white
default for an unformatted display
is always green
43 character set 00=default character set YES YES
40-EF local ID for loadabe character
sets
F0-F7 local ID for non-loadable
character sets
F8-FE local ID for two byte coded
character sets

10 - Outbound Structured Fields

general format:

<-- structured field 1 -----> <--- structured field 2 --

Write Structured Length 1 ID information length 2 ID information
Field Command'F3' 2 bytes 1byt n bytes

<-------- length 1 ---------> <--------- length 2 ------

Outbound structured fields:

ID name parameters
00 Reset Partition byte3=PID
01 Read Partition byte3=PID
byte4=TYPE 2=Query
3=Query list
6E=Read modified all
F2=Read buffer
F6=Read modified
byte5=REQTYP
byte6-n=QCODES
03 Erase/Reset byte3=flags
06 Load Programmed Symbols up to 11 parameters
09 Set reply mode byte3=PID,byte4=mode,byte5-n=attr list
0B Set window origin byte3=PID,byte4-5=RW,byte6-7=CW
0C Create Partition up to 27 parameters
00 Destroy Partition byte3=PID
0E Activate Partition byte3=PID
40 Outbound 3270DS directs 3270 data stream to a named partition
41 SCS data byte3=PID,byte4-n=data
4A Select Format group byte3=PID,byte4-n=format group
4B Present Absolute Format byte3=PID,byte4=FPC,byte5=WCC,byte6-n=name
4C Present relative format byte4-5=FOV,byte6=FPC,byte7=WCC,byte8-n=name
0F01 Set MSR control byte4=PID,byte5=1,byte6=state mask,
byte7=state value,byte8=IND mask
byte9=ind value
0F0A Modify Partition up to 29 parameters
0F71 Outbound text header up to 14 paaameters
0FC1 Outbound type 1 text byte4=PID,byte5-6 must be 0,byte 7-n=text

Outbound/Inbound Structured Fields

0F02 Destination/origin byte4=flags,byte5=0,byte6-7=ID
0F1F OEM data byte4=0,byte5=group,byte6=0,byte7-n=data
1034 Save/Restore format byte4=flags,byte5-n=FPCB

11 - Inbound Data Stream (terminal to host)

Outbound data stream | Inbound data stream

(from host to terminal) | (from terminal to host)

------------------------+---------------------------

| |

| |

S E S CU CU

T S command T add add data stream..

X C X |

| -------------+------------

v | AID | Cursor | text ..

see | code| address |

section x | | 2 bytes |

+-----+-----------+--------

or

---------------------------------------------

| AID | Structured | | Structured |

| code| Field | ... | Field | ...

| '88'| | | |

+-----+------------+------+------------+------

The following orders may be embedded in the text string:

Order EBCDIC ASCII

Start Field (SF) X'1D' X'1D' field attribute data..

Start Field Extended (SFE) X'29' note number of attribute attribute

type-value type type

pairs

Set Buffer Address (SBA) X'11' X'11' buffer address (2 bytes)

Set attribute (SA) X'28' note attribute attribute

type value

Graphic escape (GE) X'08' note character code


12 - Attention Identification (AID) bytes

AID EBCDIC ASCII
graphic (hex) (hex)
No AID generated 60 2D
No AID generated (printer only) Y E8 59
Structured Field h 88
Read partition / 61
Trigger action " 7F
Test REQ and SYS REQ 0 F0 30
PF1 key 1 F1 31
PF2 key 2 F2 32
PF3 key 3 F3 33
PF4 key 4 F4 34
PF5 key 5 F5 35
PF6 key 6 F6 36
PF7 key 7 F7 37
PF8 key 8 F8 38
PF9 key 9 F9 39
PF10 key : 7A 3A
PF11 key # 7B 23
PF12 key @ 7C 40
PF13 key A C1 41
P114 key B C2 42
PF15 key C C3 43
PF16 key D C4 44
PF17 key E C5 45
PF18 key F C6 46
PF19 key G C7 47
PF20 key H C8 48
PF21 key I C9 49
PF22 key c 4A 5B
PF23 key . 4B 2E
PF24 key < 4C 3C
PA1 key % 6C 25
PA2 key (CNCL) > 6E 3E
PA3 key , 6B 2C
CLEAR key - 6D 5F
CLEAR PARTITION key 6A
ENTER key , 7D 27
selector-pen attention = 7E 3D
magnetic readers: Operator ID reader W 6E 57
Mag Reader Number X E7 58

13 - Inbound Structured Fields

general format:

<-- structured field 1 -----> <--- structured field 2 --

AID '88' Length 1 ID information length 2 ID information
2 bytes 1byt n bytes

<-------- length 1 ---------> <--------- length 2 ------

Inbound structured fields:

ID name parameters
80 Inbound 3270DS byte3=PID,byte4=AID,byte5-6=CURSOR
byte7-n=DATA
81 Query Reply byte3=QCODE,byte4=PLIST
QCODES:
81 usable area
83 text partitions
84 alpha partitions
85 character sets
86 colour
87 highlight
88 reply modes
8A field validation
8B MSR control
8C field outlining
8F OEM aux device
90 Format presentation
91 DBCS-asia
92 save/restore format
95 DDM
99 AUXDA
A0 Device characteristics
A1 RPQ names
A2 data streams
A6 implicit partitions
FF null
0FB1 inbound text header byte4=pid,byte5=AID,byte6-8=reserved
byte9=LVL,byte10-11=CRO,byte12-13=CC
byte14-15=RW,byte16-17=CW,byte18-19=HW
byte20-21=WW
0FC1 inbound type1 text byte4=PID,byte5-6=RES,byte7-n=data

14 - EBCDIC character codes

15 - ASCII character codes


16 - Sample traces

The following traces were taken Using a Telenex Autoscope tee'd in to an

IBM PC connected to a Telenet 3006 making a call to a Tandem computer

acting as a host (Mediat).

emulated on IBM PC PSS Mediat

................... .......... ....................

. . . . . .

. terminal 3274 . ------ . . . .

. - ---- . | |X.25. . . .

. -/ +-| +-.-| 3006 +----..........--. Tandem .

. +---| +----| . +------| | . . . Host .

. . | . . . .

................... | .......... ....................

|

---+-----

| |

| our |

| tester |

+---------|


The trace is read as follows:

sync timestamp hex coding of

character | data on line

| | |

v v v

from 3010 to host - High BCD --> FFs314:58:5844772FF

low BCD --> FFy2 00FFDFF

from host to 3010 - High BCD --> FFFF FFFFFFF

low BCD --> FFFF FFFFFFF

-------------------

Trace 1

This trace shows text from the terminal to the host followed by a

Erase/Write from the host

Events 1,4 & 5 are BSC protocol only (see IBM-BSC.TXT Martin Baker)

Inbound - terminal to host (event 2)

0447C65554CDEE4CDED45554FF4FC0F5

200D20CCC08623046650CCC000076321

This can be decoded as follows:

02 BSC header

40 " "

40 " "

7D AID code (enter key pressed)

C2 cursor address (row 2, col 80)

60 " "

5C *

5C *

5C *

40 sp

C8 H

D6 O

E2 S

E3 T

40 sp

C4 D

D6 O

E6 W

D5 N

40 sp

5C *

5C *

5C *

40 sp

F0 0

F0 0

40 sp

F7 7

C6 F

03 BSC trailer

F2 " "

51 " "

Outbound - host to terminal (event 3)

02FC14416CE4CCD4

2753100D02309240

EDCCD44444444444444444444444444441C65554CCDD4CCECDDDCCECC45551C41551FCCEECDCECDD

399130000000000000000000000000000120CCC0313304923655533540CCC150D0CD045239513965

71413C661F1CDEECEEEECD7143CE6133F1CECCECCC7143CF61F1CF1551FDCDCCEC4DDCDECD7143C4

AD03C50DD0165242282354AD0C68DD220178455935AD0C78DD0180D0CD0953512507995359AD0C9C

61F1441551FCCDDE4CDDDCCE4CEECDDE161464DDCCC4CEDED44CE47574CDC4DDCEE4CDECD073

DD01A0D0CD0126930365553301335473D01C007313503492690130DCD0154079522055359397

This can be decoded as follows:

02 STX BSC HEADER

27 ESC " "

F5 ERASE/WRITE command

C3 WCC = reset partition characters to defaults,keyboard restore,MDT=1

11 Set buffer address

40 " " " to row 1 col 1

40 " " "

1D Start Field

60 attribute character (protected,alphanumeric field,blue)

CE4CCD4EDCCD4444444444444444444444444444

2309240399130000000000000000000000000000

BT IBM TRIAL

11 Set buffer address

C2 " " " Row 3 Col 1

60 " " "

5554CCDD4CCECDDDCCECC4555

CCC0313304923655533540CCC

*** CALL DISCONNECTED ***

11 Set buffer address

C5 " " " row 5 column 1

40 " " "

1D Start Field

50 attribute character (unprotected numeric,green)

5C *

1D Start Field

F0 attribute character (protected numeric,blue)

CCEECDCECDD7

45239513965A

DESTINATION:

1D Start Field

40 attribute character (unprotected,alphanumeric,green)

13 insert cursor

3C repeat to address

C5 " " " final address is row 5 col 33

60 " " "

6D " " " repeated character is "-"

1D start field

F0 attribute character (protected numeric,blue)

11 set buffer address

C6 " " " row 11 col 6

D5

EECEEEECD7

242282354A

SUBSYSTEM:

1D Start Field

40 attribute character (unprotected alphanumeric,green)

3C repeat to address

C6 " " " inish address= row 6 col 25

E8 " " "

6D " " " character "-"

1D Start field

32 BSC sync characters

32 " " "

F0 attribute character (numeric protected,blue)

11 Set buffer address

C7 " " " row 7, col 9

E8 " " "

CCECCC7

455935A

DEVICE:

1D Start Field

40 attribute character (unprotected,alphanumeric,green)

3C Repeat to address

C7 " " " finish address row 7, col 25

F8 " " "

6D " " " character "-"

1D start field

F0 attribute character (protected,numeric,blue)

11 Set buffer address

C8 " " "

F0 " " "

1D Start Field

50 attribute character (unprotected,numeric,green)

5C C

1D Start Field

F0 attribute character (protected,numeric,blue)

DCDCCEC4DDCDECD7

953512507995359A

RELEASE PRINTER:

1D Start Field

40 attribute character (unprotected,alphanumeric,green)

3C Repeat to address

C9 " " " row 7 col 47

4C " " " character "<"

6D " " "

1D Start Field

F0 attribute character (protected,numeric,blue)

11 Set buffer Address

4A " " " Row 9 Col 1

40 " " "

1D Start Field

50 attribute character (upprotected,numeric,green)

5C *

1D Start Field

F0 attribute character (protected,numeric)

CCDDE4CDDDCCE4CEECDDE

126930365553301335473

ABORT CONNECT ATTEMPT

1D Start Field

60 attribute character (protected,alphanumeric,blue)

11 Set buffer Address

4C " " " row 11 col 1

60 " " "

4DDCCC4CEDEDD4CE47574CDC4DDCEE4CDECD

07313503492690130DCD0154079522055359

PLACE CURSOR AT '*' AND PRESS ENTER

03 ETX BSC trailer

79 BCC

37 BCC

17 - conclusions

3270 datastream has evolved to become a complex and powerful protocol for communicating with terminals, it allows some of the processing to be devolved to remote terminal clusters, 3270 is independent of the data link protocol and terminal clusters such as the 3274 can send the datastream over BSC,SNA,X25 or X21 links.

 


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