Lincoln Laboratory
July 21, 1971
Categories: D.2, D.3
Related: 109, 110, 105, 158
The EBCDIC Codes and Their Mapping to ASCII
Abstract
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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
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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
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a) IBM recommends the following ASCII duals with the basic EBCDIC
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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
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graphics.
Graphic Code l X'6A' l X'79' [diagonal slash] X'A1' ~ X'E0' [diagonal slash] XC0' { XD0' }
II. Publishing Correspondence
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a) Associate the following special EBCDIC graphics with the
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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
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a) Associate the following basic EBCDIC graphics with the indicated
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ASCII graphics because of their graphic similarity.
| X'4F' with | |
[upper right corner] X'5F' with ~
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b) Associate the basic EBCDIC graphic for cent with the ASCII graphic
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for reverse slash.
[cent] X'4A' with [diagonal slash]
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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'
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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 24To 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.
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EBCDIC Questionnaire
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- 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) _____________- Do you concur with the definition of the standard EBCDIC code, including TELNET control codes?
YES __________ NO __________ Comments: __________________________________________________________________ __________________________________________________________________ __________________________________________________________________- 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. 7474Figure 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
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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
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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
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*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-
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Figure 6:
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Publishing and Printing Graphics
Also on the TN Print Chain
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** 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
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* 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.