84 they pushed cassette drives out of the US home computer market. 5.25" floppy disk drives would remain standard until the end of the 8-bit era. Though external 3.5" drives were made available for home computer systems toward the latter part of the 1980s, almost all software sold for 8-bit home computers remained on 5.25" disks; 3.5" drives were used for data storage. Standardization of disk formats was not common; sometimes even different models from the same manufacturer used different disk formats. Almost universally the floppy disk drives available for 8-bit home computers were housed in external cases with their own controller boards and power supplies contained within. Only the later, advanced 8-bit home computers housed their drives within the main unit; these included the TRS-80 Model III, TRS-80 Model 4, Apple IIc, and Commodore 128D. The later 16-bit machines such as the Atari 1040ST (not the 520ST), the Commodore Amigas, and the Tandy 1000s did house floppy drive(s) internally. At any rate, to expand any computer with additional floppy drives external units would have to be plugged in.
Toward the end of the home computer era, drives for a number of home computer models appeared offering disk-format compatibility with the IBM PC. The disk drives sold with the Commodore 128, Amiga and Atari ST were all able to read and write PC disks, which themselves were undergoing the transition from 5.25" to 3.5" format at the time (though 5.25" drives remained common on PCs until the late 1990s, due to existence of the large software and data archives on five-inch floppies). 5.25" drives were made available for the ST, Amiga and Macintosh, otherwise 3.5" based systems with no other use for a 5.25" format. Hard drives were never popular on home computers, remaining an expensive, niche product mainly for BBS sysops and the few business users.
Various copy protection schemes were developed for floppy disks; most were broken in short order. Many users would only tolerate copy protection for games, as wear and tear on disks was a significant issue in an entirely floppy-based system. The ability to make a "working backup" disk of vital application software was seen as important. Copy programs that advertised their ability to copy or even remove common protection schemes were a common category of utility software in this pre-DMCA era.
In another defining characteristic of the home computer, instead of a command line, the BASIC interpreter served double duty as a user interface. Coupled to a character-based screen or line editor, BASIC's file management commands could be entered in direct mode. In contrast to modern computers, home computers most often had their operating system (OS) stored in ROM chips. This made startup times very fast – no more than a few seconds – but made OS upgrades difficult or impossible without buying a new unit. Usually only the most severe bugs were fixed by issuing new ROMs to replace the old ones at the user's cost. Also, the small size and limited scope of home computer "operating systems" (really little more than what today would be called a kernel) left little room for bugs to hide.
Although modern operating systems include extensive programming libraries to ease development and promote standardization, home computer operating systems provided little support to application programs. Professionally written software often switched out the ROM based OS anyway to free the address space it occupied and maximize RAM capacity. This gave the program full control of the hardware and allowed the programmer to optimize performance for a specific task. Games would often turn off unused I/O ports, as well as the interrupts that served them. As multitasking was never common on home computers, this practice went largely unnoticed by users. Most software even lacked an exit command, requiring a reboot to use the system for something else.
In an enduring reflection of their early cassette-oriented nature, most home computers loaded their disk operating system (DOS) separately from the main OS. The DOS was only used