Ram cartridge
This is a continuation of co-pending application Ser. No. 730,090, filed on May 3, 1985, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     In the central processor units of some types of computers, a RAM cartridge is used which comprises a plastic case containing one or more circuit boards. In operation of a computer system, it becomes necessary to remove the RAM cartridge from its container from time to time to insert another cartridge or for some other reasons, and, in some hardware, it is difficult to remove these cartridges because of space considerations. 
     The present invention solves this problem by providing a RAM cartridge with tabs which can be easily manipulated to remove the cartridge from its housing. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a portion of a housing containing a cartridge embodying the invention; 
     FIG. 2 is a perspective view of the cartridge of the invention; 
     FIG. 3 is a plan view of the inside surface of the cartridge of the invention with the cover removed; 
     FIG. 4 is a plan view of the apparatus of FIG. 3; 
     FIG. 5 is a view of a locking tab of the invention taken along the line 5--5 in FIG. 3; and 
     FIGS. 6 through 9 illustrate the operation of the invention through its various stages of motion. 
    
    
     DESCRIPTION OF THE INVENTION 
     A cartridge 10 embodying the invention is adapted to be inserted in a slot 20 in a housing represented by the numeral 30 and comprising, for example, a portion of a central processor unit of a computer. Of course, a cartridge embodying the invention may be used in other applications as those skilled in the art will appreciate. The cartridge 10 comprises a base 40 which is sufficiently deep to receive a circuit card and a cover 50 which couples to the base. The base 40 is defined by, and its depth is provided by, a bottom wall 60, two side walls 70 and 80, an upper wall 90, and a lower wall 100, all of which rise from the bottom wall 60 to provide the depth for housing a printed circuit board 140. The upper wall 90 of the base 40 is provided with two openings 110 and 120, in which tabs 130 are seated which are used to remove the cartridge 10 from the slot 20 in the housing 30. 
     Referring to FIG. 3, the inside of the base 40 has two spaced-apart posts 150, on which the tabs 130 pivot. The posts 150 are provided adjacent to the upper wall 90 and adjacent to the two side walls 70 and 80. Posts 150 may also support printed circuit board 140. As shown in FIGS. 3 and 4, the openings 110 and 120 in the upper wall 90 extend from the side walls 70 and 80 toward each other a suitable distance, and the tabs 130 fill these openings. Without the invention, described below, if the tabs 130 were pivoted, they would strike the side walls 70 and 80, and they could not pivot enough to be able to be used to remove the cartridge 10 from the slot 20. 
     The tabs 130 themselves are generally L-shaped and include a flat portion 160 which is positioned in the openings 110, 120 in the wall 90, coplanar with wall 90, and a depending wall portion 170 (FIG. 5) whoich depends from the edge of the flat portion 160 adjacent to base wall 60 of the receiver. According to the invention, the depending wall portion 170 is provided with an opening 180 which is made up of an infinite number of circles scribed on a section of a parabola. In less technical terms, the opening 180 looks like two adjacent circles overlapped and combined to form a shape which looks like a stretched heart, the one on the left oriented from upper left to lower right, and the one on the right oriented from upper right to lower left. There is also a bump 190 at the lowest point of the openings 180. 
     The tabs 130 are provided with roughened portions or striations 184 on their outer surfaces. 
     In operation of the invention, referring to FIGS. 6-9, assume that the cartridge 10 is inserted in the slot 20 in the housing 30, with the tabs 130 lying flat in the upper wall of the cartridge receiver portion. In this orientation, the lower portions of the openings 180 in the tabs 130 have the posts 150 at their centers, and the posts are held in place by the bumps 190 (FIG. 8). To remove the cartridge 10, the tabs 130 are rotated and pushed forwardly by the fingers of the user bearing on the striations 184, and this force causes the rear portions of the tabs to drop downwardly and the openings 180 to move downwardly. During this operation and movement of the parts, the posts 150 appear to move from the portion of the openings 180 in which they are locked toward the other portions of the openings 180, as shown in FIGS. 7 and 8, and, as the tabs are pivoted, finally, the posts are positioned in the other circular portions of the openings 180 (FIG. 9). This movement spaces the tabs 130 a suitable distance from the side walls 70 and 80 of the base of the cartridge, as seen in FIGS. 8 and 9, so that the tabs can be pivoted and grasped by the user, and the cartridge can be pulled out of the slot in the housing.