Here's one way to send BOB-4 commands in C:

printf ("%c[2J I just cleared the screen!", 27);



And a general-purpose discussion from comp.lang.c FAQ list:

Question 19.9

Q: How do I send escape sequences to control a terminal or other device? 

A: If you can figure out how to send characters to the device at all (see
question 19.8), it's easy enough to send escape sequences. In ASCII, the ESC
code is 033 octal (27 decimal), so code like 
	fprintf(ofd, "\033[J");

sends the sequence ESC [ J . 

Some programmers prefer to parameterize the ESC code, like this:
	#define ESC 033

	fprintf(ofd, "%c[J", ESC);



Here's a BOB-4 application code fragment that does something useful:


int Test_Display()
{
	int Line = 0;
	// Clear The Screen
	fprintf (ComPort,"%c[2J",EscChar);

	for (Line = 0; Line<20; Line++)
	{
		fprintf(ComPort,"%c[%d;5H    Line %d    \n",EscChar,Line,
Line);
	}



	fprintf(ComPort,"%c[18;5H Hit Anykey To
Continue",EscChar,EscChar,EscChar);
	fflush(ComPort);
	getch();
	// Clear The Screen
	fprintf (ComPort,"%c[2J",EscChar);

	fprintf(ComPort,"%c[0;5H %c[1mTesting BOLD
Line%c[22m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[2;5H %c[2mTesting FAINT
Line%c[22m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[4;5H %c[10mTesting FONT Line",EscChar,EscChar);
	fprintf(ComPort,"%c[6;5H %c[7mTesting REVERSE
Line%c[27m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[8;5H %c[5mTesting BLINK
Line%c[25m",EscChar,EscChar,EscChar);
	
	fprintf(ComPort,"%c[18;5H Hit Anykey To
Continue",EscChar,EscChar,EscChar);
	fflush(ComPort);
	getch();	
	// Clear The Screen
	fprintf (ComPort,"%c[2J",EscChar);

	fprintf(ComPort,"%c[1;5H %c[14mTesting FONT 14
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[2;5H %c[13mTesting FONT 13
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[3;5H %c[11mTesting FONT 11
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[4;5H %c[10mTesting FONT 10
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[6;5H %c[18mTesting FONT 18
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[8;5H %c[19mTesting FONT 19
%c[10m",EscChar,EscChar,EscChar);				
	fprintf(ComPort,"%c[11;5H %c[15mTesting FONT 15
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[15;5H %c[16mTesting FONT 16
%c[10m",EscChar,EscChar,EscChar);

	fprintf(ComPort,"%c[18;5H Hit Anykey To
Continue",EscChar,EscChar,EscChar);
	fflush(ComPort);
	getch();
	// Clear The Screen
	fprintf (ComPort,"%c[2J",EscChar);

	fprintf(ComPort,"%c[1;2H %c[65m1. Testing Different Background
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[2;2H %c[66m2. Testing Different Background
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[3;2H %c[67m3. Testing Different Background
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[4;2H %c[68m4. Testing Different Background
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[5;2H %c[69m5. Testing Different Background
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[6;2H %c[77m6. Testing Different Background
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[7;2H %c[78m7. Testing Different Background
%c[10m",EscChar,EscChar,EscChar);
	fprintf(ComPort,"%c[8;2H %c[79m8. Testing Different Background
%c[10m",EscChar,EscChar,EscChar);
	
	fprintf(ComPort,"%c[18;2H Hit Anykey To View
Graphics",EscChar,EscChar,EscChar);
	fflush(ComPort);
	getch();
	// Clear The Screen
	fprintf (ComPort,"%c[2J",EscChar);


	// View Circle
	fprintf (ComPort,"%c[50;0;12 .r",EscChar);
	fprintf (ComPort,"%c[50;5;330 )r",EscChar);
	fprintf (ComPort,"%c[/r",EscChar);
	
	for (Round = 0;Round < 10; Round++)
	{
		// Cross-Hairs
		fprintf (ComPort,"%c[%d;%d .r",EscChar,Round+10,Round+10);
		fprintf (ComPort,"%c[%d;%d +r",EscChar,Round+40,Round+10);
		fprintf (ComPort,"%c[%d;%d .r",EscChar,Round+25,Round);
		fprintf (ComPort,"%c[%d;%d +r",EscChar,Round+25,Round+20);
		fprintf (ComPort,"%c[/r",EscChar);

		fflush(ComPort);
		Sleep(50);
		// Clear The Screen
		fprintf (ComPort,"%c[2J",EscChar);
	}


	// Filled Square
	fprintf (ComPort,"%c[60;10 .r",EscChar);
	fprintf (ComPort,"%c[100;10 +r",EscChar);
	fprintf (ComPort,"%c[120;60 +r",EscChar);
	fprintf (ComPort,"%c[150;10 +r",EscChar);
	fprintf (ComPort,"%c[#r",EscChar);

	// Star Shape
	fprintf (ComPort,"%c[100;100 .r",EscChar);
	fprintf (ComPort,"%c[100;150 +r",EscChar);
	fprintf (ComPort,"%c[70;110 +r",EscChar);
	fprintf (ComPort,"%c[120;125 +r",EscChar);
	fprintf (ComPort,"%c[70;140 +r",EscChar);
	fprintf (ComPort,"%c[100;100 +r",EscChar);
	fprintf (ComPort,"%c[#r",EscChar);	

	
	fprintf(ComPort,"%c[18;2H Hit Anykey To
Continue",EscChar,EscChar,EscChar);
	fflush(ComPort);
	getch();
	// Clear The Screen
	fprintf (ComPort,"%c[2J",EscChar);

	// Paint the Screen
	fprintf (ComPort,"%c[0;0 .r",EscChar);
	fprintf (ComPort,"%c[0;0;4 +r",EscChar);
	fprintf (ComPort,"%c[0;0;24 +r",EscChar);
	fprintf (ComPort,"%c[0;0;20 +r",EscChar);
	fprintf (ComPort,"%c[#r",EscChar);	

	fprintf(ComPort,"%c[18;2H Hit Anykey To
Continue",EscChar,EscChar,EscChar);
	fflush(ComPort);
	getch();
	// Clear The Screen
	fprintf (ComPort,"%c[2J",EscChar);



	return 0;
}