Computer cases come in a variety of shapes and sizes. After all, the equipment itself doesn't care if it has a case around it or not. In a zero-gravity environment, the components COULD be connected by nothing but wires and cables and function normally (though the torque provided by the spinning disks would probably twist cables and cause the drives to bounce around at the ends of their wires, possibly striking other components, the walls or furnishings, and maybe shorting something out, causing a huge fire that kills several people through burns and smoke inhalation, if somebody doesn't first spin a weightless drop of liquid that is harmless until it hits an electrical component at which time it converts into a noxious gas that, while it doesn't in itself kill, disables the voluntary nerves, causing the computer user to die because he CAN'T FEED HIMSELF!). But I digress. All in all, I'll stick with a case.
Cases can be made for laptop, notebook or fixed location use. I'm going to concern myself with the fixed location cases. This is because the characteristics of laptops and notebooks have similar qualities but on a smaller scale. Desktop cases sit flat and the disk drives and motherboard also sit flat. In a mini-tower or tower case the motherboard sits vertical while the disk drives normally sit horizontal. Some cases have 3.5" format drive bays that mount vertically.
Power supply, motherboard and disk drives mount to the case. Buying a case usually means buying a power supply as these are sold as a unit. A panel on the front has the power, turbo and reset switches and also has the power, turbo and hard disk LED's. It also sometimes has a keylock switch. These switches and lights connect to pin headers on the motherboard.
On the bottom panel is where the motherboard is mounted. Plastic stand-offs clip into the motherboard at certain locations and metal stand-off screws are screwed into the panel. Fobs on the plastic stand-off clips slide into slots on the panel and screw holes are lined up over the stand-off screws. The motherboard is now screwed in place.
In the front of the case are the drive bays. The drive bays on today's desktop computers come in two standard formats, 5.25" and 3.5". The large 5.25", half-height disk drive will just fit into a 5.25" bay and is screwed in at four screw holes on its sides. Some five and a quarter drive bays are wider than that and you must screw on guides that fit into the bay slots. Three and a half inch drive bays fit the smaller hard disks and 3.5" floppy drives. Again, the drives are normally secured with four screws. Mounting kits can be added to 3.5" drives to make them fit into cases that have 5.25" but no 3.5" drive bays.
On the back of the case are the expansion slots. On a typical, non-riser case, there are seven or eight expansion slots perpendicular from the motherboard. They allow cable connections to the expansion cards without opening up the case. On the top of each slot is a place for the spoon on the card to be screwed down so that the card will not slide out of its slot.
So, the case holds four major components: 1) Power Supply 2) Motherboard 3) Disk Drives 4) Expansion Cards. And, of course, the cabling that connects these components one to the other.
Updated January 24, 1998, 10:52pm. firstname.lastname@example.org