const
     TRMIN     = 1;
     TRMOUT    = 2;
     PRINTER   = 3;
     ENDFILE   = 26;   {end-of-file char. returned by getc}
     EOS       = 0;
     ENDSTR    = EOS;
     FBUFSIZE  = 1024; {file buffer size, must be multiple of SECTSIZE}
     SECTSIZE  = 128;  {CP/M sector size}
     CASEDIFF  = 32;   { ord('a') - ord('A') }
     MAXSTR    = 82;
     MAXTEXT   = 80;
     IOERROR   = 0;
     IONAVAIL  = IOERROR;
     IOAVAIL   = 7;
     IOREAD    = 2;
     IOWRITE   = 3;
     IOAPPEND  = 4;
     MODEMASK  = $07;
     BINMASK   = $80;
     BINARY    = $80; {this bit set hi in mode byte means no ^Z at end of file}
     MAXOPEN   = 7;
     null      = 0;
     bel       = 7;
     bks       = 8;
     tab       = 9;
     newline   = 10;
     lf	       = 10;
     cr	       = 13;
     eofchar   = 26; {CP/M end-of-file}
     esc       = 27;
     us	       = 31;
     space     = 32;
     exclam    = 33;
     dquote    = 34;
     numsign   = 35;
     dollar    = 36;
     percent   = 37;
     amper     = 38;
     squote    = 39;
     lparen    = 40;
     rparen    = 41;
     star      = 42;
     plus      = 43;
     comma     = 44;
     minus     = 45;
     hyphen    = 45;
     period    = 46;
     slash     = 47;
     DIGIT0    = 48;
     DIGIT1    = 49;
     DIGIT2    = 50;
     DIGIT3    = 51;
     DIGIT4    = 52;
     DIGIT5    = 53;
     DIGIT6    = 54;
     DIGIT7    = 55;
     DIGIT8    = 56;
     DIGIT9    = 57;
     colon     = 58;
     semicol   = 59;
     semicolon = semicol;
     less      = 60;
     equals    = 61;
     greater   = 62;
     question  = 63;
     atsign    = 64;
     CAPA      = 65;
     CAPB      = 66;
     CAPC      = 67;
     CAPD      = 68;
     CAPE      = 69;
     CAPF      = 70;
     CAPG      = 71;
     CAPH      = 72;
     CAPI      = 73;
     CAPJ      = 74;
     CAPK      = 75;
     CAPL      = 76;
     CAPM      = 77;
     CAPN      = 78;
     CAPO      = 79;
     CAPP      = 80;
     CAPQ      = 81;
     CAPR      = 82;
     CAPS      = 83;
     CAPT      = 84;
     CAPU      = 85;
     CAPV      = 86;
     CAPW      = 87;
     CAPX      = 88;
     CAPY      = 89;
     CAPZ      = 90;
     lbrack    = 91;
     backslash = 92;
     rbrack    = 93;
     caret     = 94;
     underline = 95;
     uscore    = underline;
     grave     = 96;
     SMALLA    = 97;
     SMALLB    = 98;
     SMALLC    = 99;
     SMALLD    = 100;
     SMALLE    = 101;
     SMALLF    = 102;
     SMALLG    = 103;
     SMALLH    = 104;
     SMALLI    = 105;
     SMALLJ    = 106;
     SMALLK    = 107;
     SMALLL    = 108;
     SMALLM    = 109;
     SMALLN    = 110;
     SMALLO    = 111;
     SMALLP    = 112;
     SMALLQ    = 113;
     SMALLR    = 114;
     SMALLS    = 115;
     SMALLT    = 116;
     SMALLU    = 117;
     SMALLV    = 118;
     SMALLW    = 119;
     SMALLX    = 120;
     SMALLY    = 121;
     SMALLZ    = 122;
     lbrace    = 123;
     bar       = 124;
     rbrace    = 125;
     tilde     = 126;
     del       = 127;
type
     character = 0..127;
     ctabtype  = array[0..127] of char;
     textline  = array[1..MAXSTR] of character;
     filedesc  = IOERROR..MAXOPEN;
     string80  = string[80]; {internal strings, used to interface w. built-in
			      non-standard procedures, functions }
     fbuf      = array[1..FBUFSIZE] of byte; { file buffer }
     ioblock   = record	 { info needed to access one disk i/o channel }
		    filevar   :file;
		    fbufptr   :^fbuf;
		    eofflag   :boolean;
		    bufindx   :integer;
		    reccnt    :integer;	 {record count, used only in read mode}
		    lastrec   :integer;	 {last record, used only in read mode}
		    mode      :byte;
		 end;
var
     openlist  :array[1..MAXOPEN] of ioblock;
     chartbl   :ctabtype;