EBCDIC Codes and Their Mapping to ASCII
RFC 183

Document Type RFC - Unknown (July 1971; No errata)
Last updated 2013-03-02
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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.

Winett                                                          [Page 1]
RFC 183         EBCDIC Codes and Their Mapping to ASCII    July 21, 1971

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.

Winett                                                          [Page 2]
RFC 183         EBCDIC Codes and Their Mapping to ASCII    July 21, 1971

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'
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