system, showing the basic layout of a typical home computer system of the era. Pictured are the CPU/keyboard unit, floppy disk drive, and dedicated color monitor. Many systems also had a
dot matrix printer for producing paper output.
KC 85/3 with its keyboard placed on top, released by VEB Mikroelektronik Mühlhausen 1976 and based on a
Zilog Z80 clone
Electronika BK0010.01 home computer was based on the
К1801ВМ1 (Soviet
LSI-11-compatible CPU) and was, basically, a variation of
PDP-11. Many home computers were superficially similar. Most had a keyboard integrated into the same case as the
motherboard, or, more frequently, a
mainboard. While the expandable home computers appeared from the very start (the
Apple II offered as many as seven expansion slots) as the whole segment was generally aimed
downmarket, few offers were priced or positioned high enough to allow for such expandability. Some systems have only one expansion port, often realized in the form of cumbersome "sidecar" systems, such as on the
TI-99/4, or required finicky and unwieldy
ribbon cables to connect the expansion modules. Sometimes they were equipped with a cheap
membrane or
chiclet keyboard in the early days, although full-travel keyboards quickly became universal due to overwhelming consumer preference. Most systems could use an
RF modulator to display 20–40 column text output on a home television. Indeed, the use of a television set as a display almost defines the pre-PC home computer. Although dedicated
composite or "
green screen" computer displays were available for this market segment and offered a sharper display, a monitor was often a later purchase made only after users had bought a
floppy disk drive, printer, modem, and the other pieces of a full system. The reason for this was that while those TV-monitors had difficulty displaying the clear and readable 80-column text that became the industry standard at the time, the only consumers who
really needed that were the power users utilizing the machine for business purposes, while the average casual consumer would use the system for games only and was content with the lower resolution, for which a TV worked fine. An important exception was the
Radio Shack TRS-80, the first mass-marketed computer for home use, which included its own 64-column display monitor and full-travel keyboard as standard features. This "
peripherals sold separately" approach is another defining characteristic of the home computer era. A first-time computer buyer who brought a base C-64 system home and hooked it up to their TV would find they needed to buy a
disk drive (the
Commodore 1541 was the only fully-compatible model) or
Datasette before they could make use of it as anything but a game machine or
TV Typewriter. In the early part of the 1980s, the dominant
microprocessors used in home computers were the
8-bit MOS Technology 6502 (Apple, Commodore, Atari,
BBC Micro) and
Zilog Z80 (
TRS-80,
ZX81,
ZX Spectrum,
Commodore 128,
Amstrad CPC). One exception was the
TI-99/4, announced in 1979 with a 16-bit
TMS9900 CPU. The TI was originally to use the 8-bit 9985 processor designed especially for it, but this project was cancelled. However, the
glue logic needed to retrofit the 16-bit CPU to an 8-bit 9985 system negated the advantages of the more powerful CPU. Another exception was the Soviet
Elektronika BK series of 1984, which used the fully-16-bit and powerful for the time
1801 series CPU, offering a full
PDP-11 compatibility and a fully functional
Q-Bus slot, though at the cost of very anemic
RAM and graphics. The
Motorola 6809 was used by the Radio Shack
TRS-80 Color Computer, the
Fujitsu FM-7, and
Dragon 32/64. Processor
clock rates were typically 1–2 MHz for 6502 and 6809-based CPUs and 2–4 MHz for Z80-based systems (yielding roughly equal performance), but this aspect was not emphasized by users or manufacturers, as the systems' limited RAM capacity, graphics abilities, and storage options had a more perceivable effect on performance than CPU speed. For low-price computers, the cost of RAM chips contributed greatly to the final product price to the consumer, and fast CPUs demanded expensive, fast memory. As a result, designers kept clock rates only adequate. In some cases, like the Atari and Commodore 8-bit machines, coprocessors were added to speed processing of graphics and audio data. For these computers, clock rate was considered a technical detail of interest only to users needing accurate timing for their own programs. To economize on component cost, often the same
crystal used to produce color television-compatible signals was also divided down and used for the processor clock. This meant processors rarely operated at their full rated speed, and had the side-effect that
European and
North American versions of the same home computer operated at slightly different speeds and different video resolution due to different television standards. Initially, many home computers used the then-ubiquitous
compact audio cassette as a storage mechanism. A rough analogy to how this worked would be to place a recorder on the phone line as a file was uploaded by
modem to "save" it, and playing the recording back through the modem to "load". Most cassette implementations were notoriously slow and unreliable, but 8-inch drives were too bulky for home use, and early 5.25-inch form-factor drives were priced for business use, out of reach of most home buyers. An innovative alternative was the
Exatron Stringy Floppy, a continuous-loop tape drive which was much faster than a
data cassette drive and could perform much like a floppy disk drive. It was available for the
TRS-80 and some others. A closely related technology was the
ZX Microdrive, developed by
Sinclair Research in the UK, for their
ZX Spectrum and
QL home computers. Eventually, mass production of 5.25-inch drives resulted in lower prices, and after about 1984, they pushed cassette drives out of the US home computer market. In other markets, such as the UK, the purchasing power of home computer customers was significantly less, leaving disk-based systems from American manufacturers such as Commodore and Apple unaffordable and in the realm of low-end business systems. 5.25-inch floppy disk drives would remain standard until the end of the 8-bit era. Though external 3.5-inch drives were made available for home computer systems during the second half of the 1980s, almost all software sold for 8-bit home computers remained on 5.25-inch disks. 3.5-inch drives were used for data storage, with the exception of the Japanese
MSX standard, on which 5.25-inch floppies were never popular. 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,
MSX2, and
Commodore 128D. The later 16-bit machines, such as the
Atari 1040ST (not the 520ST),
Amiga, and
Tandy 1000, 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-inch format at the time (though 5.25-inch 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-inch drives were made available for the ST, Amiga, and Macintosh, otherwise 3.5-inch based systems with no other use for a 5.25-inch 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. In addition, 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 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.
PCs at home 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 computer users. 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, or 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 avoid cannibalizing sales of the profitable PC. IBM management believed that if they made the PCjr too powerful, too many buyers would prefer it over the bigger, more expensive PC. Poor reviews in the computer press and poor sales doomed the PCjr.
Tandy Corporation capitalized on IBM's blunder with its PCjr-compatible
Tandy 1000 in November. Like the PCjr, it was pitched as a home, education, and small-business computer, featuring joystick ports, better sound and graphics (same as the PCjr but with enhancements), combined with near-PC/DOS compatibility (unlike Tandy's earlier
Tandy 2000). The improved Tandy 1000 video hardware became a standard of its own, known as
Tandy Graphics Adapter or TGA. Later, Tandy produced Tandy 1000 variants in form factors and price-points even more suited to the home computer market, comprised particularly by the Tandy 1000 EX and HX models (later supplanted by the 1000 RL), which came in cases resembling the original Apple IIs (CPU, keyboard, expansion slots, and power supply in a slimline cabinet) but also included floppy disk drives. The proprietary
Deskmate productivity suite came bundled with the Tandy 1000s. Deskmate was suited to use by computer novices with its point-and-click (though not graphical) user interface. From the launch of the Tandy 1000 series, their manufacture were price-competitive because of Tandy's use of high-density
ASIC chip technology, which allowed their engineers to integrate many hardware features into the motherboard (obviating the need for circuit cards in expansion slots as with other brands of PC). Tandy never transferred its manufacturing operation to Asia; all Tandy desktop computers were built in the USA (this was not true of the laptop and pocket computers, nor peripherals). In 1985, the
Epson corporation, a popular and respected producer of inexpensive dot-matrix printers and business computers (the
QX-10 and
QX-16), introduced its low-cost
Epson Equity PC. Its designers took minor shortcuts, such as few expansion slots and a lack of a socket for an
8087 math chip, but Epson did bundle some utility programs that offered decent turnkey functionality for novice users. While not a high performer, the Equity was a reliable and compatible design for half the price of a similarly configured IBM PC. Epson often promoted sales by bundling one of their printers with it at cost. The Equity I sold well enough to warrant the furtherance of the Equity line with the follow-on Equity II and Equity III. In 1986, UK home computer maker
Amstrad began producing their
PC1512 PC-compatible for sale in the UK. Later, they would market the machine in the US as the PC6400. In June 1987, an improved model was produced as the PC1640. These machines had fast
8086 CPUs, enhanced
CGA graphics, and were feature-laden for their modest prices. They had joystick adapters built into their keyboards and shipped with a licensed version of the
Digital Research's
GEM, a
GUI for the MS-DOS operating system. They became marginal successes in the home market. In 1987, longtime small computer maker
Zenith introduced a low-cost PC they called the
EaZy PC. This was positioned as an "appliance" computer much like the original Apple Macintosh: turnkey startup, built-in monochrome video monitor, and lacking expansion slots, requiring proprietary add-ons available only from Zenith, but instead with the traditional MS-DOS
Command-line interface. The EaZy PC used a turbo NEC V40 CPU (up-rated 8088), which was rather slow for its time, but the video monitor did feature 400-pixel vertical resolution. This unique computer failed for the same reasons as did IBM's PCjr: poor performance and expandability, and a price too high for the home market. Another company that offered low-cost PCs for home use was
Leading Edge, with their Model M and
Model D computers. These were configured like full-featured business PCs, yet still could compete in the home market on price because Leading Edge had access to low-cost hardware from their Asian manufacturing partners
Mitsubishi with the Model M and
Daewoo with the Model D. The
LEWP was bundled with the Model D. It was favorably reviewed by the computer press and sold very well. By the mid '80s, the market for inexpensive PCs for use in the home market was expanding at such a rate that the two leaders in the US,
Commodore and Atari, themselves felt compelled to enter the market with their own lines. They were only marginally successful compared to other companies that made only PCs. Still, later prices of
white box PC clone computers by various manufacturers became competitive with the higher-end home computers (see below). Throughout the 1980s, costs and prices continued to be driven down by: advanced circuit design and manufacturing, multi-function expansion cards,
shareware applications such as
PC-Talk,
PC-Write, and
PC-File, greater hardware reliability, and more user-friendly software that demanded less customer support services. The increasing availability of faster processor and memory chips, inexpensive
EGA and
VGA video cards,
sound cards, and joystick adapters also bolstered the viability of PC/DOS computers as alternatives to specially made computers and game consoles for the home.
High performance From about 1985, the high end of the home computer market began to be dominated by "next-generation" home computers using the 16-bit
Motorola 68000 chip, which enabled the greatly increased abilities of the
Amiga and
Atari ST series (in the UK, the
Sinclair QL was built around the
Motorola 68008 with its external 8-bit bus). Graphics resolutions approximately doubled to give roughly
NTSC-class resolution, and color palettes increased from dozens to hundreds or thousands of colors available. The Amiga was built with a custom
chipset with dedicated graphics and sound
coprocessors for high-performance video and audio. The Amiga found use as a workstation for
desktop video, a first for a stand-alone computer, costing far less than dedicated motion-video processing equipment costing many thousands of dollars. Stereo sound became standard for the first time; the Amiga has stereo sound, then Acorn Archimedes, and later Atari STe; the earlier Atari ST gained popularity as an affordable alternative for
MIDI equipment for the production of music (MIDI supports stereo for all computers, not just the Atari ST that made it popular, MIDI is also possible to use with the Amiga). Clock rates on the 68000-based systems were approximately with RAM capacities of (for the base Amiga 1000) up to (, a milestone, first seen on the Atari 1040ST). These systems used 3.5-inch floppy disks from the beginning, but 5.25-inch drives were made available to facilitate data exchange with IBM PC compatibles. The Amiga and ST both had
GUIs with windowing technology. These were inspired by the
Macintosh, but at a list price of , the Macintosh itself was too expensive for most households. The Amiga in particular had true
multitasking capability, and unlike all other low-cost computers of the era, could run multiple applications in their own windows. The second generation of
MSX computers (MSX2) achieved the performance of high-performance computers using a high-speed video processor (
Yamaha V9938) capable of handling resolutions of 512424 pixels, and 256 simultaneous colors from a palette of 512.
MSX MSX was a standard for a home computing architecture that was intended and hoped to become a universal platform for home computing. It was conceived, engineered and marketed by
Microsoft Japan with
ASCII Corporation. Computers conforming to the MSX standard were produced by most all major Japanese electronics manufacturers, as well as two Korean ones and several others in Europe and South America. Some 5 million units are known to have been sold in Japan alone. They sold in smaller numbers throughout the world. Due to the "price wars" being waged in the USA home computer market during the 1983-85 period, MSX computers were never marketed to any great extent in the USA. Eventually, more advanced mainstream home computers and game consoles obsoleted the MSX machines. The MSX computers were built around the
Zilog Z80 8-bit processor, assisted with dedicated video graphics and audio coprocessors supplied by
Intel,
Texas Instruments, and
General Instrument. MSX computers received a great deal of software support from the traditional Japanese publishers of game software.
Microsoft developed the
MSX-DOS operating system, a version of their popular
MS-DOS adapted to the architecture of these machines, which was also able to run
CP/M software directly == Radio frequency interference ==