 for disk and file related commands and was not required to perform other computing functions. One exception was Commodore DOS, which was not loaded into the computer's main memory at all – Commodore disk drives contained a 6502 processor and ran DOS from internal ROM. While this gave Commodore systems some advanced capabilities – a utility program could sideload a disk copy routine onto the drive and return control to the user while the drive copied the disk on its own – it also made Commodore drives more expensive and difficult to clone.
Many home computers had a cartridge interface which accepted ROM-based software. This was also used for expansion or upgrades such as fast loaders. Application software on cartridge did exist, which loaded instantly and eliminated the need for disk swapping on single drive setups, but the vast majority of cartridges were games.
From the introduction of the IBM Personal Computer (ubiquitously known as the PC) in 1981, the market for computers meant for the corporate, business, and government sectors came to be dominated by the new machine and its MS-DOS operating system. Even basic PCs cost thousands of dollars and were far out of reach for typical home computerists. However, in the following years technological advances and improved manufacturing capabilities (mainly greater use of robotics and relocation of production plants to lower-wage locations in Asia) permitted several computer companies to offer lower-cost PC style machines that would become competitive with many 8-bit home-market pioneers like Radio Shack, Commodore, Atari, Texas Instruments, and Sinclair. PCs could never become as affordable as these because the same price-reducing measures were available to all computer makers. Furthermore, software and peripherals for PC style computers tended to cost more than those for 8-bit computers because of the anchoring effect caused by the pricey IBM PC. As well, PCs were inherently more expensive since they could not use the home TV set as a video display. Nonetheless, the overall reduction in manufacturing costs narrowed the price difference between old 8-bit technology and new PCs. Despite their higher absolute prices PCs were perceived by many to be better values for their utility as superior productivity tools and their access to industry-standard software. Another advantage was the 8088/8086's wide, 20-bit address bus: the PC could access more than 64 kilobytes of memory relatively inexpensively (8-bit CPUs, which generally had multiplexed 16-bit address buses, required complicated, tricky memory management techniques like bank-switching). Similarly, the default PC floppy was double-sided with about twice the storage capacity of floppy disks used by 8-bit home computers. PC drives tended to cost less because they were most often built-in, requiring no external case, controller, and power supply. The faster clock rates and wider buses available to later Intel CPUs compensated somewhat for the custom graphics and sound chips of the Commodores and Ataris. In time the growing popularity of home PCs spurred many software publishers to offer gaming and children's software titles.
Many decision makers in the computer industry believed there could be a viable market for office workers who used PC/DOS computers at their jobs and would appreciate an ability to bring diskettes of data home on weeknights and weekends to continue work after-hours on their "home" computers. So the ability to run industry-standard MS-DOS software on affordable, user-friendly PCs was anticipated as a source of new sales. Furthermore, many in the industry felt that MS-DOS would eventually (inevitably, it seemed) come to dominate the computer business entirely, and some manufacturers felt the need to offer individual customers PC-style products suitable for the home market.
In early 1984 market colossus IBM produced the PCjr as a PC/DOS-compatible machine aimed squarely at the home user. It proved a spectacular failure because IBM deliberately limited its capabilities and expansion possibilities in order to av