Mainframe housing of a personal computer

Claim 1

A mainframe housing comprising a rectangular metal base frame having two opposite square sides and two pairs of opposite rectangular sides with borders connected between the square sides, a front panel covered on one rectangular side of said base frame, two rectangular cover panels fastened to two opposite rectangular sides of said base frame, and at least one square cover panel respectively covered on the square sides of said base frame, wherein: one pair of the two pairs of opposite rectangular sides of said base frame comprises two rows of lugs longitudinally and bilaterally disposed along the border, a retaining hole near one end, rows of hooks longitudinally disposed between said rows of lugs, and one row of sliding slots longitudinally disposed between one row of lugs and said rows of hooks; each rectangular cover panel comprises a front flange forced into engagement with said front panel, a plurality of longitudinally grooved reinforcing ribs at an inner side, a plurality of rows of crossed tenons respectively respectively disposed in said longitudinally grooved reinforcing ribs and respectively forced into the sliding slots of one rectangular side of said base frame, a rear finger strip, and a hook raised from said rear finger strip and forced into engagement with one retaining hole of said base frame; each square cover panel comprises two rows of inward hooks respectively forced into engagement with the lugs of said base frame, a finger strip, and a hook raised from the finger strip and forced into engagement with a respective retaining hole on said base frame.