chore: Add course material

397/DOS_Unix/Keyboard_DOS.cpp

@@ -0,0 +1,13 @@
+#include "Keyboard.h"
+#include <conio.h>
+
+Keyboard::Keyboard() {}
+
+bool Keyboard::isCharAvail() {
+    //  'return kbhit()' is sufficient, but Microsoft
+    //  issues a warning 'coercing int to bool' and encourages
+    //  the use of '!=0' to eliminate it
+    return _kbhit() != 0;
+}
+
+char Keyboard::getChar() { return _getch(); }