unsigned char cpunext(unsigned short opcode)
{
	int w = 0;
	unsigned char screenUpdated = 0;
	unsigned char height = 0;
	unsigned char* image;
	int numOfLines = 0;
	switch ((opcode & 0xF000) >> 12)
	{
		case 0x0:
			if ((opcode & 0x00F0) >> 4 == 0xC)
			{
				numOfLines = opcode & 0x000F;
				SCHIP_ScrollScreenDown(numOfLines);
				screenUpdated = true;
			}

			switch	(opcode & 0x00FF)
			{
				case 0xE0:
					Screen_Clear();
					screenUpdated = true;
					break;

				case 0xEE:
					PC = PopOffStack();
					break;

				case 0xFB:
					SCHIP_ScrollScreenRight();
					screenUpdated = true;
					break;

				case 0xFC:
					SCHIP_ScrollScreenLeft();
					screenUpdated = true;
					break;

				case 0xFD:
					stop = true;
					break;

				case 0xFE:
					mode = CHIP8_SCREEN;
					screenUpdated = true;
					break;

				case 0xFF:
					mode = SCHIP8_SCREEN;
					screenUpdated = true;
					break;

			}
			break;

		case 0x1:
			PC = (opcode & 0x0FFF)-2;
			break;

		case 0x2:
			PushToStack(PC);
			PC = (opcode & 0x0FFF)-2;
			break;

		case 0x3:
			if (registers[((opcode & 0x0F00) >> 8)] == (opcode & 0x00FF))
				PC += 2;
			break;

		case 0x4:
			if (registers[((opcode & 0x0F00) >> 8)] != (opcode & 0x00FF))
				PC += 2;
			break;

		case 0x5:
			if (registers[((opcode & 0x0F00) >> 8)] == registers[((opcode & 0x00F0) >> 4)])
				PC += 2;
			break;

		case 0x6:
			registers[((opcode & 0x0F00) >> 8)] = opcode & 0x00FF;
			break;

		case 0x7:
			registers[((opcode & 0x0F00) >> 8)] += opcode & 0x00FF;
			break;

		case 0x8:
			switch (opcode & 0x000F)
			{
				case 0x0:
					registers[((opcode & 0x0F00) >> 8)] = registers[((opcode & 0x00F0) >> 4)];

					break;

				case 0x1:
					registers[((opcode & 0x0F00) >> 8)] |= registers[((opcode & 0x00F0) >> 4)];
					break;

				case 0x2:
					registers[((opcode & 0x0F00) >> 8)] &= registers[((opcode & 0x00F0) >> 4)];
					break;

				case 0x3:
					registers[((opcode & 0x0F00) >> 8)] ^= registers[((opcode & 0x00F0) >> 4)];
					break;

				case 0x4:
					w = (int)(registers[((opcode & 0x0F00) >> 8)]) + (int)(registers[((opcode & 0x00F0) >> 4)]);

					if (w > 255)
						registers[0xF] = 1;
					else
						registers[0xF] = 0;

					registers[((opcode & 0x0F00) >> 8)] = w;
					break;

				case 0x5:
					if (registers[((opcode & 0x0F00) >> 8)] >= registers[((opcode & 0x00F0) >> 4)])
						registers[0xF] = 1;
					else
						registers[0xF] = 0;

					registers[((opcode & 0x0F00) >> 8)] -= registers[((opcode & 0x00F0) >> 4)];
					break;

				case 0x6:
					registers[0xF] = registers[((opcode & 0x0F00) >> 8)] & 0x1;
					registers[((opcode & 0x0F00) >> 8)]  >>= 1;
					break;

				case 0x7:
					if (registers[((opcode & 0x00F0) >> 4)] >= registers[((opcode & 0x0F00) >> 8)])
						registers[0xF] = 1;
					else
						registers[0xF] = 0;

					registers[((opcode & 0x0F00) >> 8)] = registers[((opcode & 0x00F0) >> 4)] - registers[((opcode & 0x0F00) >> 8)];
					break;

				case 0xE:
					registers[0xF] = (registers[((opcode & 0x0F00) >> 8)] >> 7) & 0x01;
					registers[((opcode & 0x0F00) >> 8)] <<= 1;
					break;

			}
			break;

		case 0x9:
			if (registers[((opcode & 0x0F00) >> 8)] != registers[((opcode & 0x00F0) >> 4)]) PC += 2;
			break;

		case 0xA:
			I = opcode & 0x0FFF;
			break;

		case 0xB:
			PC = (opcode & 0x0FFF) + registers[0];
			break;

		case 0xC:
			registers[((opcode & 0x0F00) >> 8)] = (rand() % 255) & (opcode & 0x00FF);
			break;

		case 0xD:
			height = (opcode & 0x000F);
			image = (unsigned char*)(RAM+I);
			registers[15] = DrawSprite(registers[GetHexPart(opcode,2)], registers[GetHexPart(opcode,3)], image, height); //set flag
			screenUpdated = true;
			break;

		case 0xE:
			switch (opcode & 0x00FF)
			{
				case 0x9E:
					if (key[registers[((opcode & 0x0F00) >> 8)]] == 1)
						PC += 2;
					break;

				case 0xA1:
					if ((key[registers[((opcode & 0x0F00) >> 8)]] == 0))
						PC += 2;
					break;

			}
			break;

		case 0xF:
			switch (opcode & 0x00FF)
			{
				case 0x07:
					registers[((opcode & 0x0F00) >> 8)] = D_Timer;
					break;

				case 0x0A:
					PC -= 2;
					for (unsigned char n=0; n < 16; n++)
					{
						if (key[n] == 1)
						{
							registers[((opcode & 0x0F00) >> 8)] = n;
							PC += 2;
							break;
						}
					}
					break;

				case 0x15:
					D_Timer = registers[((opcode & 0x0F00) >> 8)];
					break;

				case 0x18:
					S_Timer = registers[((opcode & 0x0F00) >> 8)];
					break;

				case 0x1E:
					if ((I += registers[((opcode & 0x0F00) >> 8)]) > 0xfff)
						registers[0xF] = 1;
					else
						registers[0xF] = 0;
					break;

				case 0x29:
					I = registers[((opcode & 0x0F00) >> 8)] * 5;
					break;

				case 0x30:
					I = registers[((opcode & 0x0F00) >> 8)] * 10 + 80;
					break;

				case 0x33:
					w = registers[((opcode & 0x0F00) >> 8)];
					RAM[I] = (w - (w % 100)) / 100;
					w -= RAM[I] * 100;
					RAM[I+1] = (w - (w % 10)) / 10;
					w -= RAM[I+1] * 10;
					RAM[I+2] = w;
					break;

				case 0x55:
					for (int n=0; n <= ((opcode & 0x0F00) >> 8); n++)
						RAM[I++] = registers[n];
					break;

				case 0x65:
					for (int n=0; n <= ((opcode & 0x0F00) >> 8); n++)
						registers[n] = RAM[I++];
					break;

				case 0x75:
					for (int i=0; i <= ((opcode & 0x0F00) >> 8); i++)
						Flags[i] = registers[i];
					break;

				case 0x85:
					for (int i=0; i <= ((opcode & 0x0F00) >> 8); i++)
						registers[i] = Flags[i];
					break;


			}
			break;


	}
	return screenUpdated;
}