private int CPU_Read(uint address, int size, int offset, byte[] data)
{
    int ticks = 0;
    int length = 0;
    int val, i = 0;

    if (size > data.Length)
        length = data.Length;
    else
       length = size;

    comport.DiscardInBuffer();
    comport.DiscardOutBuffer();

    //opcode read
    command[0] = CPU_CMD_READ;
    //address
    command[1] = (byte)(address);
    command[2] = (byte)(address >> 8);
    command[3] = (byte)(address >> 16);
    command[4] = (byte)(address >> 24);
    //length
    command[5] = (byte)length;

    comport.Write(command, 0, 6);

    while (comport.BytesToRead == 0)
    {
         Thread.Sleep(1);
         ticks++;
         if (ticks > 10000)
             return 0;
    }

    //comport.Read(data, offset, length);

    while (comport.BytesToRead > 0)
    {
        val = comport.ReadByte();
        data[i] = (byte)val;
        i++;

         if (i > length)
             break;
    }
            
     return i;
}