rfc1205.txt

著名的RFC文档,其中有一些文档是已经翻译成中文的的.


RFC 1205                 5250 Telnet Interface             February 1991


   completed, the server will continue with the following restore
   operation:

   Server: Sends the saved           LLLL12A0 00000400 00050412
           screen to be restored,    <Saved Screen> FFEF
           Opcode = Restore Screen.

   (No reply is necessary from the client)

   Server: Sends Read Modified       000E12A0 00000400 00010452 0000FFEF
           Data Tag (MDT) command,
           opcode = Invite.

   At this point the client would "invite" the workstation and enter the
   state that it was in prior to the System Request key being hit.

5.  5250 Data Stream Enhancements

   This section is intended to be used as an addendum to the IBM 5250
   Information Display System, Functions Reference Manual.  Described
   here are enhancements to the 5250 data stream which are not yet
   documented in the current version of that manual.  The current
   version of that manual at the time of this writing has the IBM
   publication number SA21-9247-6.  Also described in this section are
   corrections to erroneous information contained in SA21-9247-6.
   Listed below are the specific corrections and enhancements, with an
   approximate page number reference to the above manual.

5.1  Errors or Inconsistencies in SA21-9247-6

   The Insert Cursor (IC) order on pages 2-136 and 2-137 is incorrectly
   listed with a value of Hex 03; the correct value is Hex 13.

   On page 2-137, the listed "Restrictions" for the Insert Cursor,
   Repeat to Address, and Set Buffer Address orders should be updated to
   describe how Row and Column values must be valid for the current
   display screen size (either 24 x 80 or 27 x 132).

5.2  Enhancements to Existing 5250 Data Stream Commands/Orders

   A new flag is added to the second byte of the Control Character on
   page 2-40.  This flag is used to specify whether the cursor should be
   moved or not moved at the end of the Write to Display processing.
   Bit 1 of the second byte, which was previously reserved, will now be
   used for this flag.  If bit 1 is a 0, the cursor continues to be
   moved to the system IC address on a Lock-to-Unlock keyboard
   transition.  If bit 1 is a 1, the cursor is not moved.




Chmielewski                                                     [Page 7]

RFC 1205                 5250 Telnet Interface             February 1991


   A new Field Control Word (FCW) will be added on page 2-65 to indicate
   an entry field contains transparent data.  This means the entry field
   contents are sent from the display screen directly to the host at
   read time with no formatting.  Therefore, an entry field can contain
   any values (Hex 00 to Hex FF).  A transparent field is indicated by a
   Hex 84xx FCW, where xx is any value.  Note: unpredictable results
   will occur if a field is defined as both signed numeric and a
   transparent field.

   The Read Immediate, Read Input Fields, and Read MDT Fields commands
   have been enhanced to include support for transparent fields (page
   2-5).  If a transparent FCW is found for an input field, the field
   data is not formatted (for example, nulls are not converted to
   blanks).

   The restriction listed for the Set Buffer Address (SBA) order (page
   2-138) on the column address equal to zero is no longer always the
   case.  A reference to Start of Field (SF) row 1/column 1 field
   support should be made.  A note should be added in SF to describe Row
   1/Column 1 field support.  A Row 1/Column 1 field is defined by a SBA
   of row 1/column 0, followed by an SF.  For a Row 1/Column 1 input
   field, the first input-capable position is row 1/column 1.  If the SF
   defines an input field, the screen attribute is not allowed to be
   nondisplay.  Writing of the screen attribute is suppressed for a Row
   1/Column 1 field and the attribute discarded.

5.3  New 5250 Data Stream Commands/Orders

   The Read MDT Fields Alternate input command has been added.  It is
   the same as the Read MDT Fields command except:

      - The command is indicated by a X'82'
      - Leading and embedded nulls within the field remain as nulls

   The Read MDT Fields Immediate Alternate input command has been added.
   It is the same as the Read MDT Fields Alternate command except:

      - The command is indicated by a X'83'
      - The command is an immediate read command like Read Immediate;
        therefore, no control characters follow the command byte,
        field data is returned immediately, and the aid code is X'00'.

   The Move Cursor order (MC) has been added (page 2-137).  The MC order
   moves the cursor to the location specified by the two bytes following
   the order.  Byte 1 gives the row address and byte 2 gives the column
   address.  The MC order is useful when the cursor is to be moved
   without affecting the system IC address.  The MC order is unaffected
   by the Write to Display control character values including the "Leave



Chmielewski                                                     [Page 8]

RFC 1205                 5250 Telnet Interface             February 1991


   Cursor" flag (CC1 bit 1).  If more than one MC or IC are found in the
   data stream, the cursor will move to the address specified in the
   last MC or IC.

   Restrictions:

     A parameter error will be posted when:
      - There are fewer then two bytes following the order.
      - The row address is zero or greater than the number of
        rows on the display screen.
      - The column address is zero or greater than the number of
        columns on the display screen.

   Format:

     Move Cursor Order  Byte 1        Byte 2

          X'14'       Row Address   Column Address

   Results:

     The address specified by the MC order is used to move the
     cursor when the Write to Display is completed.

   The Transparent Data order (TD) has been added (page 2-137).  The TD
   order is followed by two length bytes and transparent data.  The
   transparent data is written to the display screen at the current
   display address; any values (Hex 00 to Hex FF) are allowed in the
   transparent data.  All length values are valid as long as the end of
   the display screen is not overwritten.

   Restrictions:

     A parameter error will be posted when:
      - There are fewer then two bytes following the order.
      - There are fewer bytes in the data stream then specified in the
        length field.
      - Attempting to write beyond the end of the display screen.

   Format:

     TD Order   Bytes 1 and 2           Bytes 3 to ?

       X'10'    Length of transparent   Transparent data
                data (not counting
                length bytes)





Chmielewski                                                     [Page 9]

RFC 1205                 5250 Telnet Interface             February 1991


   Results:
     The transparent data is written to the display.

   The Query command is a new input command (page 2-5) and is used by
   the server to obtain information on the functional capabilities of
   the client 5250 display.  When the client receives a Query command,
   the client sends a Query Reply describing its capabilities back to
   the server.

   The Query command must follow an Escape ('04'X) and Write Structured
   Field command ('F3'X).  The format of the Query command is as
   follows:

      Byte       Value        Description
     ======     =======   ========================
      0-1       X'0005'   Length of command
       2         X'D9'    Command Class
       3         X'70'    Command Type - Query
       4         X'00'    Flag Byte
        Bit 0:   B'0'     - Query Command
        Bit 1-7:          - Reserved (set to zero)

   The format of the Query Reply is as follows:

      Byte   Value         Description
     =====  ========  ===================================
      0-1   X'0000'   Cursor Row/Column (set to zero)
       2    X'88'     Inbound Write Structured Field Aid
      3-4   X'003A'   Length of Query Reply
       5    X'D9'     Command Class
       6    X'70'     Command Type - Query
       7    X'80'     Flag Byte
        Bit 0:   B'1'  - Query Reply
        Bit 1-7:       - Reserved (set to zero)
      8-9            Controller Hardware Class
            X'0001'   - Local Twinax Controller
            X'0061'   - Local ASCII Controller
            X'0101'   - SDLC/X.21/X.25 Twinax Controller
                            (5394 emulating a 5294)
            X'0103'   - SDLC/X.21/X.25 Twinax Controller (5394)
            X'0200'   - PC DOS non-DBCS WSF
            X'0300'   - OS/2 non-DBCS WSF
            X'0400'   - PC DOS DBCS WSF
            X'0500'   - OS/2 DBCS WSF
            X'0600'   - Other WSF or any other 5250 Emulator
     10-12           Controller Code Level
            X'010300' - For example, Version 1 Rel 3.0
     13-28  X'00'    Reserved (set to zero)



Chmielewski                                                    [Page 10]

RFC 1205                 5250 Telnet Interface             February 1991


      29             Device Type
            X'01'     - 5250 Display or 5250 Emulation
     30-33  C'cccc'  Device Type (e.g. 3180 for 3180 Mod 2)
     34-36  C'ccc'   Device Model (e.g. 002 for 3180 Mod 2)
      37             Keyboard ID
            X'02'     - Standard Keyboard
            X'82'     - G Keyboard
      38    X'00'    Extended Keyboard ID
      39    X'00'    Reserved
     40-43  X'xxxxxxxx' Display Serial Number
     44-45           Maximum number of input fields
            X'0100'   - Typically = 256 input fields
     46-48  X'00'    Reserved (set to zero)
     49-53           Controller/Display Capability
       Bit 0-1: B'00' - No Row 1/Col 1 support
                B'01' - Row 1/Col 1 support
       Bit 2:   B'0'  - No Read MDT Alternate Command support
                B'1'  - Read MDT Alternate Command support
       Bit 3:   B'0'  - Display does not have PA1/PA2 support
                B'1'  - Display does have PA1/PA2 support
       Bit 4:   B'0'  - Display does not have PA3 support
                B'1'  - Display does have PA3 support
       Bit 5:   B'0'  - Display does not have Cursor Select support
                B'1'  - Display does have Cursor Select support
       Bit 6:   B'0'  - Display does not have Move Cursor Order support
                B'1'  - Display does have Move Cursor Order support
       Bit 7:   B'0'  - No Read MDT Immediate Alt Command support
                B'1'  - Read MDT Immediate Alt Command support
     50
       Bit 0-3: B'0001' - 24 x 80 Screen Size
                B'0011' - Capable of 24 x 80 and 27 x 132
       Bit 4:   B'0'    - No light pen support
                B'1'    - Light pen support
       Bit 5:   B'0'    - No Mag Stripe Reader support
                B'1'    - Mag Stripe Reader support
       Bit 6-7: B'00'   - Mono display
                B'01'   - 5292/3179 style color, including color PCs
     51         X'00'   - Reserved
     52
       Bit 0-2: B'000'   - No Double Byte Character Set (DBCS)
                           capability
                B'001'   - Presentation screen DBCS capability only
       Bit 3-7: B'00000' - Reserved
     53
       Bit 0-2: B'000'   - No graphics capability
                B'001'   - 5292-2 style graphics
       Bit 3-7: B'00000' - Reserved
     54-60      X'00'    Reserved (set to zero)



Chmielewski                                                    [Page 11]

RFC 1205                 5250 Telnet Interface             February 1991


6.  References

   1.  IBM, "IBM 5250 Information Display System, Functions
       Reference Manual", SA21-9247-6, March 1987.

   2.  Postel, J. and J. Reynolds, "Telnet Protocol Specification",
       RFC 854, USC/Information Sciences Institute, May 1983.

   3.  Postel, J. and J. Reynolds, "Telnet Option Specifications",
       RFC 855, USC/Information Sciences Institute, May 1983.

   4.  Postel, J. and J. Reynolds, "Telnet Binary Transmission",
       RFC 856, USC/Information Sciences Institute, May 1983.

   5.  VanBokkeln, J., "Telnet Terminal-Type Option", RFC 1091,
       FTP Software, Inc., February 1989.

   6.  Postel, J. and J. Reynolds, "Telnet End of Record Option",
       RFC 885, USC/Information Sciences Institute, December 1983.

Security Considerations

   Security issues are not discussed in this memo.

Author's Address

   Paul Chmielewski
   IBM Corporation
   Highway 52 and 37 Street North West
   Rochester, Minnesota  55901

   Phone:  [phone]

   EMail:  [e-mail]

















Chmielewski                                                    [Page 12]