pascal UpdateAnalog(int brightness,int contrast, long slotbase)
	{
	Fg2DacWrite(0x40, 7, 63 - brightness, slotbase);   /* Top of RANGE DAC */
	Fg2DacWrite(0x40, 6, 63 - contrast, slotbase);   /* difference DAC  */
	}


Fg2DacWrite(int addr,int instr,int data, long slotbase)
	{
	int				regs[4], value, i;
	
	regs[3] = 48;
	       	
	regs[3] = regs[3] | 0x10;   /* bring up SCL first (if it was off) */
	Fg2SetReg(3,regs[3],slotbase);
	regs[3] = regs[3] | 0x20;   /* bring up SDA (if it was off) */
	Fg2SetReg(3,regs[3],slotbase);
	
/* start condition */	
	regs[3] = regs[3] & ~0x20;   /* bring down SDA  */
	Fg2SetReg(3,regs[3],slotbase);
	
/* send the addr byte */
	for(i=0; i<8; i++)
		{
		regs[3] = regs[3] & ~0x10;   /* bring down SCL */
		Fg2SetReg(3,regs[3],slotbase);
		if(addr & 0x80)	 regs[3] = regs[3] |  0x20;   /* bring up SDA */
		else 			 regs[3] = regs[3] & ~0x20;   /* bring down SDA  */
		Fg2SetReg(3,regs[3],slotbase);
		addr <<= 1; /* shift up the address byte */
		regs[3] = regs[3] | 0x10;   /* bring up SCL */
		Fg2SetReg(3,regs[3],slotbase);
		}
/* get addr ack */
	regs[3] = regs[3] & ~0x10;   /* bring down SCL */
	Fg2SetReg(3,regs[3],slotbase);
	regs[3] = regs[3] |  0x20;   /* bring up SDA */
	Fg2SetReg(3,regs[3],slotbase);
	regs[3] = regs[3] | 0x10;    /* bring up SCL */
	Fg2SetReg(3,regs[3],slotbase);
	
/* send the instr byte */
	for(i=0; i<8; i++)
		{
		regs[3] = regs[3] & ~0x10;   /* bring down SCL */
		Fg2SetReg(3,regs[3],slotbase);
		if(instr & 0x80) regs[3] = regs[3] |  0x20;   /* bring up SDA */
		else 			 regs[3] = regs[3] & ~0x20;   /* bring down SDA  */
		Fg2SetReg(3,regs[3],slotbase);
		instr <<= 1; /* shift up the instruction byte */
		regs[3] = regs[3] | 0x10;   /* bring up SCL */
		Fg2SetReg(3,regs[3],slotbase);
		}
/* get instr ack */
	regs[3] = regs[3] & ~0x10;   /* bring down SCL */
	Fg2SetReg(3,regs[3],slotbase);
	regs[3] = regs[3] |  0x20;   /* bring up SDA */
	Fg2SetReg(3,regs[3],slotbase);
	regs[3] = regs[3] | 0x10;    /* bring up SCL */
	Fg2SetReg(3,regs[3],slotbase);
	
/* send the data byte */
	for(i=0; i<8; i++)
		{
		regs[3] = regs[3] & ~0x10;   /* bring down SCL */
		Fg2SetReg(3,regs[3],slotbase);
		if(data & 0x80) regs[3] = regs[3] |  0x20;   /* bring up SDA */
		else 			 regs[3] = regs[3] & ~0x20;   /* bring down SDA  */
		Fg2SetReg(3,regs[3],slotbase);
		data <<= 1; /* shift up the data byte */
		regs[3] = regs[3] | 0x10;   /* bring up SCL */
		Fg2SetReg(3,regs[3],slotbase);
		}
/* get data ack */
	regs[3] = regs[3] & ~0x10;   /* bring down SCL */
	Fg2SetReg(3,regs[3],slotbase);
	regs[3] = regs[3] |  0x20;   /* bring up SDA */
	Fg2SetReg(3,regs[3],slotbase);
	regs[3] = regs[3] | 0x10;    /* bring up SCL */
	Fg2SetReg(3,regs[3],slotbase);
	
/* stop condition */
	regs[3] = regs[3] & ~0x10;   /* bring down SCL */
	Fg2SetReg(3,regs[3],slotbase);
	regs[3] = regs[3] | 0x10;    /* bring up SCL */
	Fg2SetReg(3,regs[3],slotbase);
	regs[3] = regs[3] | 0x20;    /* bring up SDA  */
	Fg2SetReg(3,regs[3],slotbase);
	
	return;
	}


Fg2SetReg(int index,int value, long slotbase)
      {
	   char	       *reg;	                 
       reg = (char*) (0xF5FE0 + slotbase + index * 4);
       *reg = value;                         
       }