C / C++ / MFC

struct
{
    WORD wLamp1 : 1;     // <-- this sets the struct member to only be 1 bit.
    WORD wLamp2 : 1;
    WORD wLamp3 : 1;
    WORD wGap   : 4;     // <-- I'm pretending you have a gap of 4 wires, for illustration.
    WORD wFan1  : 1;
etc...
} MyHardware;

// Turn on the lamp
MyHardware.wLamp2 = 1;
SetParallelPortFunctionOfSomeKind ((WORD *)&MyHardware);

// Turn off the lamp
MyHardware.wLamp2 = 0;
SetParallelPortFunctionOfSomeKind ((WORD *)&MyHardware);

LRESULT CMyFrameWnd::OnDisplayChange(WPARAM wParam, LPARAM lParam)
{
    // cBitsPerPixel = wParam;
    // cxScreen = LOWORD(lParam);
    // cyScreen = HIWORD(lParam);

    // Redraw the window and its children
    RedrawWindow(NULL, NULL, RDW_INVALIDATE | RDW_ERASE | RDW_ALLCHILDREN | RDW_UPDATENOW);

    // Pass it on to the base class
    return CFrameWnd::OnDisplayChange(wParam, lParam);
} 

#ifdef BUILDING_DLL
#define MYDLL_API __declspec(dllexport)
#else
#define MYDLL_API __declspec(dllimport)
#endif // def BUILDING_DLL

class MYDLL_API A { /* declarations omitted */ };
class MYDLL_API B : public A { /* declarations omitted */ };