VIO Tutorial (Hello, World)

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By Johann Oskarsson

This is a short tutorial on writing text to the console, the basics, and then with some color and cursor positioning.

  • All examples have been compiled with OpenWatcom.

VIO is short for Video Input/Output, and is the console interface to eCS.

The following is a hello, world application for the eCS VIO API.

#define INCL_VIO
#include <os2.h>

int main( int argc, char *argv[] )
{
	APIRET rc = VioWrtTTY( "Hello, VIO\n", // string to write
	                       11,             // lenght of string to write
	                       0 );            // VIO handle, must be 0
	return rc;
}

This can be compiled with OpenWatcom 1.3, as such: WCL386 vio.cpp, assuming the file name of vio.cpp.

Character Attributes

Lower Nibble: Character

  • Bit 0: Blue (0x01)
  • Bit 1: Green (0x02)
  • Bit 2: Red (0x04)
  • Bit 3: Intensity (0x08)

Higher Nibble: Background

  • Bit 4: Blue (0x10)
  • Bit 5: Green (0x20)
  • Bit 6: Red (0x40)
  • Bit 7: Blink/Intensity (0x80) (VioSetState)

Color Example

#define INCL_VIO
#include <os2.h>

int main( int argc, char *argv[] )
{
   char buffer[32] = {
       'H', 12,       // intense red
       'e', 9,        // intense blue
       'l', 10,       // intense green
       'l', 12,
       'o', 9,
       ',', 10,
       ' ', 0,
       'i', 12,
       'n', 9,
       ' ', 0,
       'c', 10,
       'o', 12,
       'l', 9,
       'o', 10,
       'r', 12,
       '!', 9 };

    APIRET rc = VioWrtCellStr( buffer,
        32,         // Buffer length
        3,          // Row, 3 to allow some scrolling
        0,          // Column
        0 );        // VioHandle, must be 0

    return rc;
}