There's still a need to convert data stored in IBM's EBCDIC (Extended Binary-Coded Decimal Interchange Code) format to the more common ASCII (American Standard Code for Information Interchange). Occasionally it's necessary to do the opposite. This little filter converts in either direction.

 /* ==========================================================
    Op/System   : Unix
    Job Name    : e2a
    Module      : e2a.c
    Purpose     : Reads standard input and converts the stream
                  from EBCDIC to ASCII
                  sending it to standard output.
    Compilation : cc -o e2a e2a.c
    Parameters  : E = Convert from EBCDIC to ASCII (default)
                  A = Convert from ASCII to EBCDIC
    Usage       : cat source.file | e2a E >target.file
    ======================================================== */
 #include <sys/types.h>
 #include <stdio.h>
 #include <ctype.h>
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
 
 static unsigned char a2e[256] = {
          0,  1,  2,  3, 55, 45, 46, 47, 22,  5, 37, 11, 12, 13, 14, 15,
         16, 17, 18, 19, 60, 61, 50, 38, 24, 25, 63, 39, 28, 29, 30, 31,
         64, 79,127,123, 91,108, 80,125, 77, 93, 92, 78,107, 96, 75, 97,
        240,241,242,243,244,245,246,247,248,249,122, 94, 76,126,110,111,
        124,193,194,195,196,197,198,199,200,201,209,210,211,212,213,214,
        215,216,217,226,227,228,229,230,231,232,233, 74,224, 90, 95,109,
        121,129,130,131,132,133,134,135,136,137,145,146,147,148,149,150,
        151,152,153,162,163,164,165,166,167,168,169,192,106,208,161,  7,
         32, 33, 34, 35, 36, 21,  6, 23, 40, 41, 42, 43, 44,  9, 10, 27,
         48, 49, 26, 51, 52, 53, 54,  8, 56, 57, 58, 59,  4, 20, 62,225,
         65, 66, 67, 68, 69, 70, 71, 72, 73, 81, 82, 83, 84, 85, 86, 87,
         88, 89, 98, 99,100,101,102,103,104,105,112,113,114,115,116,117,
        118,119,120,128,138,139,140,141,142,143,144,154,155,156,157,158,
        159,160,170,171,172,173,174,175,176,177,178,179,180,181,182,183,
        184,185,186,187,188,189,190,191,202,203,204,205,206,207,218,219,
        220,221,222,223,234,235,236,237,238,239,250,251,252,253,254,255
 } ;
 
 static unsigned char e2a[256] = {
          0,  1,  2,  3,156,  9,134,127,151,141,142, 11, 12, 13, 14, 15,
         16, 17, 18, 19,157,133,  8,135, 24, 25,146,143, 28, 29, 30, 31,
        128,129,130,131,132, 10, 23, 27,136,137,138,139,140,  5,  6,  7,
        144,145, 22,147,148,149,150,  4,152,153,154,155, 20, 21,158, 26,
         32,160,161,162,163,164,165,166,167,168, 91, 46, 60, 40, 43, 33,
         38,169,170,171,172,173,174,175,176,177, 93, 36, 42, 41, 59, 94,
         45, 47,178,179,180,181,182,183,184,185,124, 44, 37, 95, 62, 63,
        186,187,188,189,190,191,192,193,194, 96, 58, 35, 64, 39, 61, 34,
        195, 97, 98, 99,100,101,102,103,104,105,196,197,198,199,200,201,
        202,106,107,108,109,110,111,112,113,114,203,204,205,206,207,208,
        209,126,115,116,117,118,119,120,121,122,210,211,212,213,214,215,
        216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,
        123, 65, 66, 67, 68, 69, 70, 71, 72, 73,232,233,234,235,236,237,
        125, 74, 75, 76, 77, 78, 79, 80, 81, 82,238,239,240,241,242,243,
         92,159, 83, 84, 85, 86, 87, 88, 89, 90,244,245,246,247,248,249,
         48, 49, 50, 51, 52, 53, 54, 55, 56, 57,250,251,252,253,254,255
 } ;
 
 /* ---------------------------------------------------
   Pass this function one ASCII character
   and receive back the equivalent EBCDIC character...
   ------------------------------------------------ */
 unsigned char ASCIItoEBCDIC(const unsigned char c)
 {
   return a2e[c];
 }
 
 /* ---------------------------------------------------
   Pass this function one EBCDIC character and receive
   the equivalent ASCII character in return...
   ------------------------------------------------ */
 unsigned char EBCDICtoASCII(const unsigned char c)
 {
   return e2a[c];
 }
 
 int main(int argc, char **argv)
 {
   char Mode;
   unsigned char InChar;
 
   /* ------------------------------------------------------
      Get the operation type (default is EBCDIC to ASCII)...
      --------------------------------------------------- */
   if(argc == 1)
      Mode = 'E';
   else
      Mode = *argv[1];
  
   /* -----------------------------
      Check we have a valid mode...
      -------------------------- */
   if(Mode != 'E' && Mode != 'A')
   {
      printf("Usage: cat <filename> | e2a [E|A]\n");
      printf("Where E = convert from EBCDIC to ASCII (default)\n");
      printf("      A = convert from ASCII to EBCDIC\n");
      exit(-1);
   }
  
   /* --------------------------------
      Still here? Do the conversion...
      ----------------------------- */
   while(!feof(stdin))
   {
       InChar = (char) getchar();
       if(Mode == 'E')
          putchar(EBCDICtoASCII(InChar));
       else
           putchar(ASCIItoEBCDIC(InChar));
   }
 }
 /* ===========================================
    END END END END END END END END END END END
    ======================================== */