Editing IBM Personal Computer (section)

=== Storage ===
The two bays in the front of the machine could be populated with one or two 5.25″ floppy disk drives, storing 160&nbsp;KB per disk side for a total of 320&nbsp;KB of storage on one disk.<ref name=":1" /> The floppy drives require a controller card inserted in an expansion slot, and connect with a single ribbon cable with two edge connectors. The IBM floppy controller card provides an external 37-pin D-sub connector for attachment of an external disk drive, although IBM did not offer one for purchase until 1986.

As was common for home computers of the era, the IBM PC offered a port for connecting a [[IBM cassette tape|cassette data recorder]]. Unlike the typical home computer however, this was never a major avenue for software distribution,<ref>{{Cite book|title=The Peter Norton Programmer's Guide to the IBM PC|publisher=Microsoft Corporation|year=1985|isbn=0914845462|quote=I have never encountered a PC program on tape for sale. In fact, about the only use of the cassette port that I am aware of is the homespun and jerry-rigged use of this port as a poor-man's serial port.}}</ref> probably because very few PCs were sold without floppy drives. The port was removed on the very next PC model, the XT.<ref>{{Cite book|last=Robert|first=Brenner|title=IBM Personal Computer: Troubleshooting & Repair for the IBM PC, PC/XT, and PC AT|publisher=Sams|year=1989|isbn=0672226626|quote=Next to the keyboard connector is a 5-pin circular connector for cassette data input/output. This connection is not available on the XT or AT.}}</ref>

At release, IBM did not offer any hard disk drive option<ref name=":0" /> and adding one was difficult - the PC's stock power supply had inadequate power to run a hard drive, the motherboard did not support BIOS expansion ROMs which was needed to support a hard drive controller, and both PC DOS and the BIOS had no support for hard disks. After the XT was released, IBM altered the design of the 5150 to add most of these capabilities, except for the upgraded power supply. At this point adding a hard drive was possible, but required the purchase of the IBM 5161 Expansion Unit, which contained a dedicated power supply and included a hard drive.<ref>{{Cite web|title=minuszerodegrees.net|url=http://www.minuszerodegrees.net/5150/hdd/5150_hard_drive_support.htm|access-date=October 3, 2020|website=www.minuszerodegrees.net}}</ref>

Although official hard drive support did not exist, the third party market did provide early hard drives that connected to the floppy disk controller{{Citation needed|date=December 2022}}, but required a patched version of PC DOS to support the larger disk sizes.