The present invention relates generally to an apparatus for securing a door in a predetermined position.  More particularly, the present invention relates to a door detent mechanism for use with a computing apparatus.  The mechanism may be used to secure a door that covers a port, receptacle, pin, or other opening in the case of the computing apparatus to secure the door in an open, closed, or intermediate position. 
Computing devices, such as personal computers, main frames, lap top computers, pocket PCs, personal digital assistants, portable analog or digital analyzers, and the like generally include one or more ports or openings through which the computing device may be connected to another device or system.  For example, a computer may include a power cord connector consisting of a plug that faces outward through an opening in the case of the computing apparatus.  The user may connect a power cord from a power source to the computing apparatus via this connector.  Similarly, modem jacks, network ports, or other openings through which a communication connection may be made may also be provided.  Other interface ports, such as parallel interface ports, serial ports, or other input/output slots may be provided.  Such ports or openings may include a pin connector that is designed to receive a cable containing pins or holes that correspond to the number and location of pins and holes on the pin connector.  One end of the cable is connected to the pin connector, while the other end of the cable is connected to a peripheral device such as a mouse, a printer, a display, a modem, a disk drive, or other peripheral plug in device. 
When peripheral devices are not connected to a computer apparatus through an input/output port, the port must be closed to prevent exposing the pin connector and/or other parts of the computer apparatus to the environment.  Dust, moisture, other contaminants, or damaging objects may enter the computer apparatus from the environment through such a port.  The potential for the entry of such substances is a particular problem with portable computing devices, such as digital analyzers, lap tops, and personal digital assistants. 
To prevent loss or damage to the port or door mechanism, and to ensure its use, it is desirable therefore that the port covering or door remain connected to the computer apparatus when it is both open and closed and that it be easily operated.  A number of different door or covering mechanisms have been developed for use in connection with portable computing apparatus such as lap top computers.  These mechanisms typically involve the use of complex mechanisms utilizing a number of small parts including small springs. 
While these mechanisms can be used on devices that are not subject to harsh environments and treatment, they would not be as useful on a device intended to be used in an environment such as an automobile shop where it is likely that the device will be dropped or hit with another tool.  There is thus still a need for a port covering or door mechanism which is easily operated, does not utilize any small parts, remains connected to the computing device, and is recessed into the device when the port is open. 
The foregoing need has been satisfied to a great extent by the present invention which includes a door detent mechanism which is permanently affixed to a computer apparatus and which secures a door held in a closed or other position over an input/output port opening.  In accordance with one embodiment of the invention, a computing apparatus has an opening.  A door, sized and positioned to cover the opening, is connected to a hinge.  The hinge includes two ends, and a pin is attached to each end of the hinge.  Two receptacles, sized and positioned to accept the hinge, are attached to the computing apparatus.  The hinge also includes at least one locking notch.  At least one finger is attached to the computing apparatus in positions so that each locking notch on the hinge will engage with a finger when the door covers the opening in a closed position. 
Preferably, the door and hinge are made of a plastic or synthetic material and include at least one groove that permits the door and hinge to be compressed for insertion of the pins into the receptacles.  Preferably, the door or the hinge includes at least one rib extending away from the computing apparatus, the rib being sized and positioned to facilitate opening of the door by a human hand. 
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings.  The invention is capable of other embodiments and of being practiced and carried out in various ways.  Also, it is to be understood that the phraseology and terminology employed herein as well as the abstract included below are for the purpose of description and should not be regarded as limiting. 
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention.  It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.