Drive bay

A drive bay is a standard-sized area for adding hardware to a computer. Most drive bays are fixed to the inside of a case, but some can be removed. Over the years since the introduction of the IBM PC, it and its compatibles have had many form factors of drive bays. Four form factors are in common use today, the 5.25-inch, 3.5-inch, 2.5-inch or 1.8-inch drive bays. These names do not refer to the width of the bay itself, but rather to the width of the disks used by the drives mounted in these bays. 8.0-inch drive bays were found in early IBM computers, CP/M computers, and the TRS-80 Model II. They were high, wide, and approximately deep, and were used for hard disk drives and floppy disk drives. This form factor is obsolete. 5.25-inch drive bays are divided into two height specifications, full-height and half-height. Full-height bays were found in old PCs in the early to mid-1980s. They were high, wide, and up to deep, used mainly for hard disk drives and floppy disk drives. This is the size of the internal (screwed) part of the bay, as the front side is actually . The difference between those widths and the name of the bay size is because it is named after the size of floppy that would fit in those drives, a 5.25-inch-wide square. Half-height drive bays are high by wide, and are the standard housing for CD and DVD drives in modern computers. They were sometimes used for other things in the past, including hard disk drives (roughly between 10 and 100 MB) and floppy disk drives. As the name indicates, two half-height devices can fit in one full-height bay. Often represented as 5.25-inch, these floppy disk drives are obsolete. The dimensions of a 5.25-inch floppy drive are specified in the SFF standard specifications which were incorporated into the EIA-741 "Specification for Small Form Factor 133.35 mm (5.25 in) Disk Drives" by the Electronic Industries Association (EIA). Dimensions of 5.25 optical drives are specified in the SFF standard (they are somewhat shorter and not only size of the body is standardized, but also size of the bezel).