faqs.org - Internet FAQ Archives

RFC 183 - EBCDIC Codes and Their Mapping to ASCII


Or Display the document by number




Network Working Group                                        J.M. Winett
Request for Comments: 183                             Lincoln Laboratory
NIC: 7127                                                  July 21, 1971

Categories: D.2, D.3
Related: 109, 110, 105, 158

              The EBCDIC Codes and Their Mapping to ASCII

Abstract

   The uniquely map the ASCII codes into corresponding EBCDIC codes in a
   consistent manner throughout the ARPA Network, this RFC describes and
   defines the IBM Standard Extended BCD Interchanged Code.

Introduction

   The IBM Corporate Systems Standard, Extended BCD Interchanged Code
   (EBCDIC) defines 8-bit graphic and control codes (See Figure 1).  The
   basic EBCDIC code consists of 54 controls (including space) and 88
   graphics.  This set is extended to include 10 special graphics and 1
   special control (EO).  These special graphics originate from the 7-
   bit hollerith code and include 6 ASCII graphics.  The EBCDIC code is
   further extended to include the publishing and printing graphics
   option which specifics 52 graphics.  Of these graphics, 32 appear on
   the IBM TN print chain.  Four of these graphics are duals with
   graphics not on the TN print chain, and one graphic (degree) is dual
   with a graphic in the special graphics set of the basic code (tilde).

   It is desirable to uniquely map the ASCII codes into corresponding
   EBCDIC codes in a consistent manner throughout the ARPA network.

   For each of the 34 ASCII controls (including space and delete) there
   is a corresponding BDCDIC control (assigning ASCII control DC3 to the
   EBCDIC code X'13').  For 85 of the 94 ASCII graphics, there is a
   corresponding graphic in the basic EBCDIC set.  Three different
   correspondences can be made for the other 9 ASCII graphics.

I.  IBM Correspondence

   a) IBM recommends the following ASCII duals with the basic EBCDIC
      graphics.

           ASCII                   EBCDIC                  Code
           [                       [cent sign]             X'4A'
           ]                       !                       X'5A'
           !                       l                       X'4F'
           [carrot sign]           [upper right corner]    X'5F'

   Note that the EBCDIC graphic for exclamation point (!) is not chosen
   to correspond to the ASCII for exclamation point (!), though this
   would be a sensible choice, and thus another code must be used to
   represent this graphic.

   b) Special EBCDIC graphics would be used to represent the other ASCII
      graphics.

           Graphic                         Code
           l                               X'6A'
           l                               X'79'
           [diagonal slash]                X'A1'
           ~                               X'E0'
           [diagonal slash]                XC0'
           {                               XD0'
           }

II.  Publishing Correspondence

   a) Associate the following special EBCDIC graphics with the
      corresponding ASCII graphics.

           Graphic                         Code
           [carrot]                        X'71'
           [                               X'AD'
           ]                               X'BD'
           {                               X'8B'
           }                               X'9B'

   The codes for open bracket and close bracket are chosen since these
   graphics appear on the TN print chain.  The codes for left brace and
   right brace are chosen rather than the codes in the special graphics
   set for opening brace and closing brace, respectively, since these
   graphics are similar and also appear on the TN print chain.

III.  Graphical Correspondence

   a) Associate the following basic EBCDIC graphics with the indicated
      ASCII graphics because of their graphic similarity.

           |                       X'4F'           with |
                                                        |

           [upper right corner]    X'5F'           with ~

   b) Associate the basic EBCDIC graphic for cent with the ASCII graphic
      for reverse slash.

           [cent]          X'4A'           with [diagonal slash]

   This choice is made since the cent graphic is not an ASCII graphic
   and is the only graphic in the basic EBCDIC set which would not
   otherwise be associated with any ACII graphic.

   c) Associate the special EBCDIC graphic grave accent.

         `  X'79'

      with the corresponding ASCII graphic.

   d) Associate the following publishing EBCDIC graphics with the
   corresponding ASCII graphics.

           [carrot]        X'71'
           [               X'AD'
           ]               X'BD'
           {               X'8B'
           }               X'9B'

   The codes for open bracket and close bracket are chosen since these
   graphic appear on the TN print chain.  The codes for left brace and
   right brace are chosen rather than the codes in the special graphics
   set for opening brace and closing brace, respectively, since these
   graphics are similar and also appear on the TN print chain.

   Standards:

   In order that the mapping from ASCII into EBCDIC and vice versa could
   become standardized, I would appreciate comments on the above from
   each site whose operating system uses EBCDIC as the internal code.

   Telnet Codes:

   For those sites who may wish to provide our use TELNET services that
   communicate using an EBCDIC code, a standard code must be specified.
   The codes given in Figure 1 can form the basis for a standard.
   Specific codes must also be specified for the TELNET control codes.
   The following are suggested:

                                   Hex Code
           sync                    38
           break                   39
           NOP                     3A
           Return to ASCII         FF
           No echo                 14
           Echo                    23
           Hide input              24

   To eliminate using one code for two graphics, I propose that the TN
   graphics be associated with their corresponding code.  The graphic
   tilde (~) might be assigned to the code X'E1' rather than keeping the
   dual with the graphic for degree.  This would have no effect if the
   Graphical Correspondence were chosen for the EBCDIC to ASCII mapping
   with the code X'5F' for logical not associated with tilde.  The other
   graphics of the publishing and printing option (Double Acute,
   Inferior Hook, Macron, and Inferior Comma) which are not on the TN
   print chain but have the same codes as graphics on the TN print chain
   would not be considered to be part of the standard EBCDIC code.

EBCDIC Questionnaire

   1. For ASCII to EBCDIC mapping of the 9 special ASCII graphics do you
      prefer:

      a)   The IBM correspondence             _____________
      b)   The Publishing correspondence      _____________
      c)   The Graphical correspondence       _____________
      d)   Another correspondence (describe)  _____________

   2. Do you concur with the definition of the standard EBCDIC code,
      including TELNET control codes?

           YES __________  NO __________

      Comments:
      __________________________________________________________________
      __________________________________________________________________
      __________________________________________________________________

   3. Please list for your operating system:

      a)   graphics not included in the complete EBCDIC code.
      b)   Graphics given a different code.
      c)   Controls given one of the graphic codes.
      d)   Controls given one of the control codes but defined to be a
           different control
      e)   All the controls which have meaning with your operating
           system (i.e., for which special action is taken) and state
           the action.

   Reply from:     Name                    _________________
                   Telephone               _________________
                   Site                    _________________
                   Host Computer           _________________

   Send to:        Joel M. Winett
                   M.I.T. Lincoln Laboratory
                   Room C-151
                   Lexington, Mass. 02173

   Or call:        (617) 862-5500 ext. 7474

   Figure 1.  [Please view the PDF version of this RFC.]

   Figure 2.  [Please view the PDF version of this RFC.]

   Hex Code      Category      Control      Name
   00            CC            NUL          Null
   01            CC            SOH          Start of Heading
   02            CC            STX          Start of Text
   03            CC            ETX          End of Text
   04            DC            PF           Punch off
   05            FE            HT           Horizontal Tab
   06            GR            LC           Lower Case
   07            GR            DEL          Delete
   08            GR            GE           Graphic Escape
   09            FE            RLF          Reverse Line Feed
   0A            CC            SMM          Start of Manual Message
   0B            FE            VT           Vertical Tab
   0C            FE            FF           Form Feed
   0D            FE            CR           Carriage Return
   0E            GR            SO           Shift Out
   0F            GR            SI           Shift In

   10            CC            DLE          Data Line Escape
   11            DC            DC1          Device Control 1
   12            DC            DC2          Device Control 2
   13            DC            TM/DC3       Tape Mark/Device Control 3
   14            DC            RES          Restore
   15            FE            NL           New Line
   16            FE            BS           Backspace
   17            DC            IL           Idle
   18            GR            CAN          Cancel
   19            DC            EM           End of Medium
   1A            DC            CC           Cursor Control
   1B            CU            CUI          Customer Use 1
   1C            IS            IFS          Info. Field Separator
   1D            IS            IGS          Info. Group Separator
   1E            IS            IRS          Info. Record Separator
   1F            IS            IUS          Info. Unit Separator

   20            ED            DS           Digit Select
   21            ED            SOS          Start of Significance
   22            ED            FS           Field Separator
   23                                       (Reserved)
   24            DC            BYP          Bypass
   25            FE            LF           Line Feed
   26            CC            ETB          End of Text Block
   27            GR            ESC          Escape
   28                                       (Reserved)
   29                                       (Reserved)
   2A            DC            SM           Set Mode
   2B            CU            CU2          Customer Use 2
   2C                                       (Reserved)

   2D            CC            ENQ          Enquiry
   2E            CC            ACK          Acknowledge
   2F            DC            BEL          Bell

   30                                       (Reserved)
   31                                       (Reserved)
   32            CC            SYN          Synchronous Idle
   33                                       (Reversed)
   34            DC            PN           Punch On
   35            DC            RS           Reader Stop
   36            GR            UC           Upper Case
   37            CC            EOT          End of Transmission
   38                                       (Reserved)
   39                                       (Reserved)
   3A                                       (Reserved)
   3B            CU            CU3          Customer Use 3
   3C            DC            DC4          Device Control 4
   3D            CC            NAK          Negative Acknowledge
   3E                                       (Reserved)
   3F            GR            SUB          Substitute

                    Figure 3: EBCDIC Control Functions

   CC    ([illegible] Control). A functional character  [illegible] to
         control or facilitate transmission of introducing [illegible]
         communication networks.

   FB    (Format Bisector). A functional character which controls the
         layout of positioning or information in printing or display
         devices.

   IS    (Information Separator). A character which is used to separate
         and qualify information in a logical sense. There is a group of
         four such characters, which are to be used in a hierarchical
         order.

   DC    (Device Control). A functional character used for the control
         of ancillary devices associated with data processing of
         telecommunication systems, more especially switching devices
         "on" and "off".

   ED    (Edit and Mark). A control character used by the
         System/[illegible]...and Mark ([illegible]) instruction for the
         formatting of alphanumeric fields.

   GH    (Graphic Control). A control character indicating that the core
         combinations which follow are to be [illegible] in a particular
         code table, depending upon the particular control character.

   CU    (Customer Use). A character excluded from future assignment by
         IBM.  These "protected" codes are intended for use by customer
         systems so that their use will not conflict with a possible
         future IBM use.

                                 Figure 4
                      Categories of Control Functions

      Hex Code             Graphic                 Name
   *   6A                  |                       Vertical Line
                           |
   *   79                  [diagonal slash]        Grave Accent
   *   A1                  ~                       Tilde
   *   C0                  {                       Opening Brace
       CC                  [hook]                  Hook
       CE                  [fork]                  Fork
   *   D0                  }                       Closing Brace
   *   E0                  /                       Reverse Slant
       EC                  [chair]                 Chair
       FA                  |                       Long Vertical Line
       FF                  EO                      Eight Ones

                     Figure 5: Special EBCDIC Graphics

   *ASCII Graphic

        Hex Code   Graphic                 Name
   **      A0      -                       Superscript Minus
   *       A1      [degree]                Degree
   *       B0      [superscript 0]         Superscript Zero
   *       B1      [superscript 1]         Superscript One
   *       B2      [superscript 2]         Superscript Two
   *       B3      [superscript 3]         Superscript Three
           B4      [superscript 4]         Superscript Four
           B5      [superscript 5]         Superscript Five
           B6      [superscript 6]         Superscript Six
           B7      [superscript 7]         Superscript Seven
           B8      [superscript 8]         Superscript Eight
           B9      [superscript 9]         Superscript Nine

           SB      {                       Left Brace
           SC      [equal or less than]    Equal or Less Than
           SD      [superscript (]         Superscript Left Parenthesis
           SE      [superscript +]         Superscript Plus Sign
           SF      +                       Plotting Cross
           9B      }                       Right Brace
           9C      [lozenge]               Lozenge
           9D      [superscript )]         Superscript Right Parenthesis
           9E      [plus or minus]         Plus or Minus
           9F      [histogram]             Histogram
           AB      [lower left corner]     Lower Left Corner
           AC      [upper left corner]     Upper Left Corner
           AD      [                       Open Square Bracket
           AE      [= or >]                Equal or Greater Than
           AF      [bullet]                Bullet (Plotting Circle)
           EB      [lower right corner]    Lower Right Corner
           EC      [upper right corner]    Upper Right Corner
           ED      ]                       Close Square Bracket
           EE      [not equal]             Not equal
           EF      ---                     Entended Dash

                Figure 6: Publishing and Printing Graphics
                          Also on the TN Print Chain

   **      Dual with the special EBCDIC graph c tilde
   *       Dual with another graphic which is not on the TN print chain

       Hex Code    Graphic                 Name
           70      [Scandinavian accent]   Scandinavian Accent
           71      [carrot]                Circumflex
           72      [diaeresis]             Diaeresis
           73      /                       Diacritical Virgule
           74      '                       Acute Accent
           75      [superior .]            Superior Dot
           76      ,                       Cedilla
           77      [breve]                 Breve
           78      [caron]                 Caron
           8A      [up arrow]              Up Arrow
           9A      [dagger]                Dagger

   *       B0      "                       Double Acute
   *       B1      '                       Inferior Hook
   *       B2      -                       Macron
   *       B3      ,                       Inferior Comma

           CD      '                       Open Quote
           DB      [pound sign]            Pound Sign
           DC      [section sign]          Section Sign
           DD      [paragraph sign]        Paragraph Sign
           ED      '                       Close Quote

             Figure 7: Publishing and Printing Graphics
                       not on the TN Print Chain

   *       Dual with another graphic which is on the TN print chain

   Name        Graphic    Hex Code     Graphic       Name
   Tilde           ~       A1         [degree]       Degree
   Double Acute    "       B0        [superscript 0] Superscript Zero
   Inferior Hook   '       B1        [superscript 1] Superscript One
   Macron  -               B2        [superscript 2] Superscript Two
   Inferior Comma ,        B3        [superscript 3] Superscript Three

                      Figure 8: Graphic Duals
   __________________________________________________________________

   Codes           Graphics               Name
   AF--75             .                   Bullet--Superior Dot
   8B--C0             {                   Left Brace--Opening Brace
   9B--D0             }                   Right Brace--Closing Brace
   61--73             /                   Slash--Diacritical Virgule
   A1--7.0         [degree]               Degree--Scandinavian Accent
   4F--FA             |                   Logical Or--Long Vertical Mark
   6B--76--B3         ,                   Comma--Cedilla-Inferior Comma
   60--B2             -                   Dash--Macron

                       Figure 9: Similar Graphics
   ____________________________________________________________________

   Name            Control  Hex Code  Graphic      Name
   Group Mark        GM      4F          |         Logical or
   Mode Change       MC      5F      [upper right corner] Logical Not
   Plus Zero         PZ      C0          {         Opening Brace
   Minus Zero        MZ      D0          }         Closing Brace
   Record Mark       RM      E0          \        Reverse Slant
   Word Separator    WS      6D          __        Underscore
   Segment Mark      SM      6F           ?        Question Mark
   Substitute Blank  SB      7A           :        Colon
   Tape Mark         TM      7F           "        Quotation Marks

                     Figure 10: Graphic Control Duals
   ____________________________________________________________________

   This material has not been reviewed for public release and is
   intended only for use with the ARPA network.  It should not be quoted
   or cited in any publication not related to the ARPA network.

 

User Contributions:

Comment about this RFC, ask questions, or add new information about this topic:

CAPTCHA