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Pascal/Delphi Source File  |  1994-12-27  |  1.2 KB  |  50 lines
  1. unit PCXCDU2;
  2.  
  3. { CDX_GetLetterNumber bugfixed, Dec 28, 1994 }
  4.  
  5. interface
  6.  
  7. var
  8.    CDR_Status     : Word;                       { Status }
  9.    CD_Letters     : Byte;                       { Number of CD-ROM devices }
  10.    CD_StartLetter : Byte;                       { Number of 1st CDR device }
  11.    CD_Current     : Word;                       { Current CDR device used }
  12.  
  13. implementation
  14.  
  15. uses DOS;
  16.  
  17. (****************************************************************************)
  18. (* CDX_GetLetterNumber
  19. (*
  20. (* Get Number of CD-ROM drive letters
  21. (*
  22. (* Input:
  23. (*    AX = $1500
  24. (* Output:
  25. (*    BL = Number of CD-ROM drive letters
  26. (*    CL = Starting drive letter of CD-ROM dirve (A=0, B=1, ...)
  27. (****************************************************************************)
  28.  
  29. procedure CDX_GetLetterNumber;
  30.  
  31. var
  32.    r : Registers;
  33.  
  34. begin
  35.    r.AX:=$1500;
  36.    r.BX:=$0000;                                 { Bugfixed }
  37.    r.CX:=$0000;                                 { Bugfixed }
  38.    Intr($2f,r);
  39.    CD_Letters:=r.BL;
  40.    CD_StartLetter:=r.CL;
  41.    CD_Current:=CD_StartLetter;
  42. end;
  43.  
  44.  
  45. {----------------------------------------------------------------------------}
  46.  
  47. begin
  48.    CDR_Status:=0;
  49.    CDX_GetLetterNumber;
  50. end.