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120-517: The abbreviation "micro" was common during the 1970s and 1980s, but has since fallen out of common usage. The term microcomputer came into popular use after the introduction of the minicomputer , although Isaac Asimov used the term in his short story " The Dying Night " as early as 1956 (published in The Magazine of Fantasy and Science Fiction in July that year). Most notably, the microcomputer replaced

240-505: A Sacramento State University team led by Bill Pentz built the Sac State 8008 computer, able to handle thousands of patients' medical records. The Sac State 8008 was designed with the Intel 8008. It had a full set of hardware and software components : a disk operating system included in a series of programmable read-only memory chips (PROMs); 8 Kilobytes of RAM; IBM's Basic Assembly Language (BAL);

360-663: A Zilog Z80 processor clocked at 1.78 MHz (later models shipped with a Z80A). The initial Level I machines shipped in late 1977-early 1978 have only 4 KB of RAM. After the Expansion Interface and Level II BASIC were introduced in mid-1978, RAM configurations of 16 KB and up were offered (the first 16 KB was in the Model ;I itself and the remaining RAM in the Expansion Interface). The OS ROMs , I/O area, video memory, and OS work space occupy

480-869: A proof of concept to demonstrate what such a simple device could do. As microprocessors and semiconductor memory became less expensive, microcomputers grew cheaper and easier to use. All these improvements in cost and usability resulted in an explosion in their popularity during the late 1970s and early 1980s. A large number of computer makers packaged microcomputers for use in small business applications. By 1979, many companies such as Cromemco , Processor Technology , IMSAI , North Star Computers , Southwest Technical Products Corporation , Ohio Scientific , Altos Computer Systems , Morrow Designs and others produced systems designed for resourceful end users or consulting firms to deliver business systems such as accounting, database management and word processing to small businesses. This allowed businesses unable to afford leasing of

600-564: A voice synthesizer , or a VOXBOX voice recognition unit. Originally, printing with the Model I required the Expansion Interface, but later Tandy made an alternative parallel printer interface available. The Model I Expansion Interface is the most troublesome part of the TRS-80 Model I system. It went through several revisions. The E/I connects to the CPU/keyboard with a 6-inch ribbon cable which

720-439: A "debounce" delay to the keyboard driver to avoid the noisy switch contacts. Tandy's KBFIX utility, the Model III, the last Model I firmware, and most third-party operating systems also implement the software fix, and Tandy changed the keyboard during the Model III's lifetime to an Alps Electric design with sealed switches. The Alps keyboard was available as an upgrade for the Model I for $ 79. The keyboard

840-496: A $ 100 deposit. Despite the internal skepticism, Radio Shack aggressively entered the market. The company advertised " The $ 599 personal computer " as "the most important, useful, exciting, electronic product of our time". Kornfeld stated when announcing the TRS-80, "This device is inevitably in the future of everyone in the civilized world—in some way—now and so far as ahead as one can think", and Tandy's 1977 annual report called

960-463: A better job, and Texas did not have a state income tax . Hired for his technical and retail experience, Leininger began working with French in June 1976. The company envisioned a kit, but Leininger persuaded the others that because "too many people can't solder", a preassembled computer would be better. Tandy had 11 million customers that might buy a microcomputer, but it would be much more expensive than

1080-399: A capacity of 180 kilobytes per single-sided floppy disk. The use of index-sync means that a " flippy disk " requires a second index hole and write-enable notch. One could purchase factory-made "flippies". Some software publishers formatted one side for Apple systems and the other for the TRS-80. The usual method of connecting floppy drives involves setting the drive letter via jumper blocks on

1200-661: A consensus definition of a minicomputer as a machine costing less than US$ 25,000 (equivalent to $ 196,000 in 2023 ), with an input-output device such as a teleprinter and at least four thousand words of memory, that is capable of running programs in a higher level language, such as Fortran or BASIC . The class formed a distinct group with its own software architectures and operating systems. Minis were designed for control, instrumentation, human interaction, and communication switching as distinct from calculation and record keeping. Many were sold indirectly to original equipment manufacturers (OEMs) for final end-use application. During

1320-451: A double-density disk controller (based on the WD 1791 chip) were made by Percom (a Texas peripheral vendor), LNW, Tandy, and others. The Percom Doubler adds the ability to boot and use double density floppies using a Percom-modified TRSDOS called DoubleDOS. The LNDoubler adds the ability to read and write 5 + 1 ⁄ 4 -inch (130 mm) diskette drives with up to 720 KB of storage, and also

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1440-575: A few proprietary minicomputer architectures survive. The IBM System/38 operating system, which introduced many advanced concepts, lives on with IBM's AS/400 . Great efforts were made by IBM to enable programs originally written for the IBM System/34 and System/36 to be moved to the AS/400. After being rebranded multiple times, the AS/400 platform was replaced by IBM Power Systems running IBM i . In contrast, competing proprietary computing architectures from

1560-492: A green-on-black display. Complaints about the video display quality were common. As Green wrote, "hells bells, [the monitor] is a cheap black and white television set with a bit of conversion for computer use". (The computer could be purchased without the Radio Shack monitor.) CPU access to the screen memory causes visible flicker . The bus arbitration logic blocks video display refresh (video-RAM reads) during CPU writes to

1680-532: A hard drive; a color display; a printer output; a 150 bit/s serial interface for connecting to a mainframe; and even the world's first microcomputer front panel. In early 1973, Sord Computer Corporation (now Toshiba Personal Computer System Corporation ) completed the SMP80/08, which used the Intel 8008 microprocessor. The SMP80/08, however, did not have a commercial release. After the first general-purpose microprocessor,

1800-535: A hardware problem that complicated loading programs from cassette recorders. Tandy offered a small board which was installed at a service center to correct the issue. The ROMs in later models were modified to correct this. Only the Model I uses an Expansion Interface; all later models have everything integrated in the same housing. The TRS-80 does not use the S-100 bus like other early 8080 and Z80-based computers. A proprietary Expansion Interface (E/I) box, which fits under

1920-488: A higher retail price to provide Tandy's typical profit margin. In February 1977 they showed their prototype, running a simple tax-accounting program, to Charles Tandy , head of Tandy Corporation. The program quickly crashed as the computer's implementation of Tiny BASIC could not handle the US$ 150,000 figure that Tandy typed in as his salary, and the two men added support for floating-point math to its Level I BASIC to prevent

2040-402: A home computer that could "do a payroll for up to 15 people in a small business, teach children mathematics, store your favorite recipes or keep track of an investment portfolio. It can also play cards." Six sacks of mail arrived at Tandy headquarters asking about the computer, over 15,000 people called to purchase a TRS-80—paralyzing the company switchboard—and 250,000 joined the waiting list with

2160-532: A hundred Micral-N were installed in the next two years, followed by a new version based on the Intel 8080. Meanwhile, another French team developed the Alvan, a small computer for office automation which found clients in banks and other sectors. The first version was based on LSI chips with an Intel 8008 as peripheral controller (keyboard, monitor and printer), before adopting the Zilog Z80 as main processor. In late 1972,

2280-502: A loss of reliability on their tape recorders. With the Model III and improved electronics in the cassette interface, the standard speed increased to 1,500 baud which works reliably on most tape recorders. For loading and storing data from tape, the CPU creates the sound by switching the output voltage between three states, creating crude sine wave audio. The first version of the Model I also has

2400-419: A minicomputer or time-sharing service the opportunity to automate business functions, without (usually) hiring a full-time staff to operate the computers. A representative system of this era would have used an S100 bus , an 8-bit processor such as an Intel 8080 or Zilog Z80 , and either CP/M or MP/M operating system. The increasing availability and power of desktop computers for personal use attracted

2520-464: A range of peripherals and software for the TRS-80, began shipping computers by September, opened its first computer-only store in October, and delivered 5,000 computers to customers by December. Still forecasting 3,000 sales a year, Radio Shack sold over 10,000 TRS-80s in its first one and a half months of sales, 55,000 in its first year, and over 200,000 during the product's lifetime; one entered

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2640-467: A recurrence. The project was formally approved on 2 February 1977; Tandy revealed that he had already leaked the computer's existence to the press. When first inspecting the prototype, he remarked that even if it did not sell, the project could be worthy if only for the publicity it might generate. MITS sold 1,000 Altairs in February 1975 and was selling 10,000 a year. When Charles Tandy asked who would buy

2760-470: A result, less expensive. They were used in manufacturing process control, telephone switching and to control laboratory equipment. In the 1970s, they were the hardware that was used to launch the computer-aided design (CAD) industry and other similar industries where a small dedicated system was needed. The boom in worldwide seismic exploration for oil and gas in the early 1970s saw the widespread use of minicomputers in dedicated processing centres close to

2880-440: A software company, and the company had rejected his attempt for a Tandy Computer Center to sell non-Tandy computers. while the company's computer success helped Roach become Tandy's CEO. Selling computers did not change the company's "schlocky" image; the Radio Shack name embarrassed business customers, and Tandy executives disliked the "Trash-80" nickname for its products. By 1984, computers accounted for 35% of sales, however, and

3000-488: A standard feature of many commercial programs. They accept an "asterisk parameter", an asterisk (star) character typed following the program name when the program is run from the TRSDOS Ready prompt. When used following a spontaneous reboot (or an accidental reset, program crash, or exit to TRSDOS without saving data to disk), the program loads without initializing its data area(s), preserving any program data still present from

3120-542: A starting price of US$ 600 (equivalent to US$ 3,000 in 2023). A cassette tape drive for program storage was included in the original package. While the software environment was stable, the cassette load/save process combined with keyboard bounce issues and a troublesome Expansion Interface contributed to the Model I's reputation as not well-suited for serious use. Initially (until 1981), it lacked support for lowercase characters which may have hampered business adoption. An extensive line of upgrades and add-on hardware peripherals for

3240-557: A time, although they can often be modified with software or hardware to concurrently serve more than one user. Microcomputers fit well on or under desks or tables, so that they are within easy access of users. Bigger computers like minicomputers , mainframes , and supercomputers take up large cabinets or even dedicated rooms. A microcomputer comes equipped with at least one type of data storage, usually RAM . Although some microcomputers (particularly early 8-bit home micros) perform tasks using RAM alone, some form of secondary storage

3360-400: Is memory-mapped so that certain locations in the processor's memory space correspond to the status of a group of keys. The color of the 12 in (300 mm) KCS 172 RCA monitor's text is faintly blue (the standard P4 phosphor used in black-and-white televisions). Green and amber filters, or replacement tubes to reduce eye fatigue were popular aftermarket items. Later models came with

3480-413: Is 64. This can be worked around by deleting the unused bit and piggybacking an eighth 2102 chip onto another. The alphanumeric symbols are displayed in 5×7 matrices of pixels . The 1978 manual for the popular word processor Electric Pencil came with instructions for modifying the computer. Although the modification needs to be disabled for Level II BASIC, its design became the industry standard and

3600-409: Is a continuous loop tape drive, dubbed the stringy floppy or ESF. It requires no Expansion Interface, plugging directly into the TRS-80's 40-pin expansion bus, is much less expensive than a floppy drive, can read and write random-access data like a floppy drive unlike a cassette tape, and it transfers data at up to 14,400 baud . Exatron tape cartridges store over 64 KB of data. The ESF can coexist with

3720-501: Is because Intel was the contractor in charge of developing the Datapoint's CPU, but ultimately CTC rejected the 8008 design because it needed 20 support chips. Another early system, the Kenbak-1 , was released in 1971. Like the Datapoint 2200, it used small-scale integrated transistor–transistor logic instead of a microprocessor. It was marketed as an educational and hobbyist tool, but it

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3840-473: Is ignored, and the eighth toggles graphics mode. The reason that the seventh bit is ignored is due to the company's decision to have only seven 2102 static-RAM chips installed on the computer's motherboard instead of eight to keep the manufacturing cost low. Thus, there are no lowercase letters in the TRS-80 character set of an unmodified Model I, and the number of both graphics symbols and alphanumeric symbols

3960-783: Is jumpered to their number on the chain, or even an IBM PC "twist" cable, which requires setting each drive number to 1, but only permits two drives on the chain. Although third-party DOSes allow the user to define virtually any floppy format wanted, the "lowest common denominator" format for TRS-80s is the baseline single-density, single-sided, 35-40 track format of the Model I. Third-party vendors like Aerocomp made available double-sided and 80 track 5 + 1 ⁄ 4 -inch and later 3 + 1 ⁄ 2 -inch floppy drives with up to 720 KB of storage each. These new drives are half-height and therefore require different or modified drive housings. An alternative to cassette tape and floppy disk storage from Exatron sold over 4,000 units by 1981. The device

4080-806: Is normally desirable. In the early days of home micros, this was often a data cassette deck (in many cases as an external unit). Later, secondary storage (particularly in the form of floppy disk and hard disk drives) were built into the microcomputer case. Although they did not contain any microprocessors, but were built around transistor-transistor logic (TTL), Hewlett-Packard calculators as far back as 1968 had various levels of programmability comparable to microcomputers. The HP 9100B (1968) had rudimentary conditional (if) statements, statement line numbers, jump statements ( go to ), registers that could be used as variables, and primitive subroutines. The programming language resembled assembly language in many ways. Later models incrementally added more features, including

4200-504: Is present in Drive 0, it hangs there until the user either presses RESET on the back of the computer, which causes it to attempt to boot the disk again, or Break + Reset was pressed, which drops the computer into BASIC. Due to the above-mentioned problems with potentially corrupting disks, it is recommended to power up to the garbage screen with the disk drives empty, insert a system disk, and then hit RESET . InfoWorld compared

4320-448: Is seldom used today; the contemporary term for this class of system is " midrange computer ", such as the higher-end SPARC from Oracle , Power ISA from IBM , and Itanium -based systems from Hewlett-Packard . The term "minicomputer" developed in the 1960s to describe the smaller computers that became possible with the use of transistors and core memory technologies, minimal instructions sets and less expensive peripherals such as

4440-406: Is sometimes pointed to as an early example of a minicomputer, as it was small, transistorized and (relatively) inexpensive. However, its basic price of $ 100,000 (equivalent to $ 1,029,921 in 2023) and custom desk-like chassis places it within the "small system" or "midrange computer" category as opposed to the more modern use of the term minicomputer. Nevertheless, it retains a strong contender for

4560-470: Is unreliable, partly because the interface lacked an external data separator (buffer). The early versions of TRSDOS were also buggy, and not helped by the Western Digital FD1771 chip which cannot reliably report its status for several instruction cycles after it receives a command. A common method of handling the delay was to issue a command to the 1771, perform several "NOP" instructions, then query

4680-405: Is unshielded against RF interference and its card edge connector tends to oxidize due to its base metal contacts. This demands periodic cleaning with a pencil eraser in order to avoid spontaneous reboots, which contributes to its "Trash-80" sobriquet. Aftermarket connectors plated with gold solved this problem permanently. Software developers also responded by devising a recovery method which became

4800-472: Is used to depress the power button and the E/I has no power LED, making it difficult to determine if it is running or not. The expansion unit requires a second power supply, identical to the base unit power supply. An interior recess holds both supplies. The user is instructed to power on and power off all peripherals in proper order to avoid corrupting data or potentially damaging hardware components. The manuals for

4920-666: The BASIC programming language (HP 9830A in 1971). Some models had tape storage and small printers. However, displays were limited to one line at a time. The HP 9100A was referred to as a personal computer in an advertisement in a 1968 Science magazine, but that advertisement was quickly dropped. HP was reluctant to sell them as "computers" because the perception at that time was that a computer had to be big in size to be powerful, and thus decided to market them as calculators. Additionally, at that time, people were more likely to buy calculators than computers, and, purchasing agents also preferred

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5040-580: The Intel 8080 , was announced in April 1974, Sord announced the SMP80/x, the first microcomputer to use the 8080, in May 1974. Virtually all early microcomputers were essentially boxes with lights and switches; one had to read and understand binary numbers and machine language to program and use them (the Datapoint 2200 was a striking exception, bearing a modern design based on a monitor, keyboard, and tape and disk drives). Of

5160-631: The Processor Technology SOL-20 was designed, which consisted of one board which included all the parts of the computer system. The SOL-20 had built-in EPROM software which eliminated the need for rows of switches and lights. The MITS Altair just mentioned played an instrumental role in sparking significant hobbyist interest, which itself eventually led to the founding and success of many well-known personal computer hardware and software companies, such as Microsoft and Apple Computer . Although

5280-661: The Smithsonian 's National Museum of American History . By mid-1978 the waits of two months or more for delivery were over, and the company could state in advertisements that TRS-80 was "on demonstration and available from stock now at every Radio Shack store in this community!" The first units, ordered unseen, were delivered in November 1977, and rolled out to the stores the third week of December. The line won popularity with hobbyists, home users, and small businesses. Tandy Corporation's leading position in what Byte magazine called

5400-537: The US$ 30 median price of a Radio Shack product, and a great risk for the very conservative company. Executives feared losing money as Sears did with Cartrivision , and many opposed the project; one executive told French, "Don't waste my time—we can't sell computers." As the popularity of CB radio —at one point comprising more than 20% of Radio Shack's sales—declined, however, the company sought new products. In December 1976 French and Leininger received official approval for

5520-487: The Western Digital 1771 single-density floppy disk controller chip. The industry standard Shugart Associates SA-400 minifloppy disk drive was used. Four floppy drives can be daisy-chained to the Model I. The last drive in the chain is supposed to have a termination resistor installed but often it is not needed as it is integrated into later cables. Demand for Model I drives greatly exceeded supply at first. The drive

5640-599: The cable spaghetti connecting the TRS-80 Model I's various components to the snakes in Raiders of the Lost Ark . Radio Shack offered a "TRS-80 System Desk" that concealed nearly all the cabling. It can accommodate the complete computer system plus up to four floppy drives and the Quick Printer. Since the cable connecting the Expansion Interface carries the system bus, it is short (about 6 inches). The user has no choice but to place

5760-566: The workstation machines opened new markets for graphics-based systems that the terminal-oriented minis could not even address. Minis retained a force for those using existing software products or those who required high-performance multitasking, but the introduction of newer operating systems based on Unix began to become highly practical replacements for these roles as well. For computational science , clusters of commodity PCs largely replaced minicomputers. Mini vendors began to rapidly disappear through this period. Data General responded to

5880-732: The "1977 Trinity" ( Apple Computer , Commodore , and Tandy) had much to do with Tandy's retailing the computer through more than 3,000 of its Radio Shack storefronts in the USA. Tandy claimed it had "7000 [Radio Shack] stores in 40 countries". The pre-release price for the basic system (CPU/keyboard and video monitor) was US$ 500 and a US$ 50 deposit was required, with a money-back guarantee at time of delivery. By 1978, Tandy/Radio Shack promoted itself as "The Biggest Name in Little Computers". By 1979 1,600 employees built computers in six factories. Kilobaud Microcomputing estimated in 1980 that Tandy

6000-506: The 1771 for the result. Early TRSDOS neglects the required yet undocumented wait period, and thus false status often returns to the OS, generating random errors and crashes. Once the 1771 delay was implemented, it was fairly reliable. In 1981, Steve Ciarcia published in Byte the design for a homemade, improved expansion interface with more RAM and a disk controller for the TRS-80. A data separator and

6120-461: The ASR ;33. Another common difference was that most earlier small machines were not "general purpose", in that they were designed for a specific role like process control or accounting . On these machines, programming was generally carried out in their custom machine language , or even hard-coded into a plugboard , although some used a form of BASIC . DEC wrote, regarding their PDP-5, that it

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6240-545: The Altair itself was only a mild commercial success, it helped spark a huge industry. By 1977, the introduction of the second microcomputer generation as consumer goods , known as home computers , made them considerably easier to use than their predecessors because their predecessors' operation often demanded thorough familiarity with practical electronics. The ability to connect to a monitor (screen) or TV set allowed visual manipulation of text and numbers. The BASIC language, which

6360-589: The CTR-41 unit with the CTR-80 which had built-in AGC circuitry (and no volume control). This helped the situation, but tape operation is still unreliable. TRS-80 Model I computers with Level I BASIC read and write tapes at 250 baud (about 30 bytes per second); Level II BASIC doubles this to 500 baud (about 60 bytes per second). Some programmers wrote machine-language programs that increase the speed to up to 2,000 bits per second without

6480-413: The E/I directly behind the computer with the monitor on top. This causes problems for a non-Tandy monitor whose case did not fit the mounting holes. Also, the friction fit of the edge connector on the already short interconnect cable makes it possible to disconnect the system bus from the CPU if either unit is bumped during operation. Radio Shack introduced floppy drives in July 1978, about six months after

6600-431: The Model I went on sale. The Model I disk operating system TRSDOS was written by Randy Cook under license from Radio Shack; Randy claimed to have been paid $ 3000 for it. The first version released to the public was a buggy v2.0. This was quickly replaced by v2.1. Floppy disk operation requires buying the Expansion Interface, which included a single-density floppy disk interface (with a formatted capacity of 85K) based on

6720-445: The Model III launch in mid-1980, Tandy stated that the Model I was still sold, but it was discontinued by the end of the year. Tandy cited one of the main reasons as being the prohibitive cost of redesigning it to meet stricter FCC regulations covering the significant levels of radio-frequency interference emitted by the original design. The Model I radiated so much interference that, while playing games, an AM radio placed next to

6840-472: The Model III was succeeded by the compatible TRS-80 Model 4 . Following the original Model I and its compatible descendants , the TRS-80 name became a generic brand used on other unrelated computer lines sold by Tandy, including the TRS-80 Model II , TRS-80 Model 2000 , TRS-80 Model 100 , TRS-80 Color Computer , and TRS-80 Pocket Computer . In the mid-1970s, Tandy Corporation 's Radio Shack division

6960-406: The TRS-80 advise turning on the monitor first, then any peripherals attached to the E/I (if multiple disk drives are attached, the last drive on the chain is to be powered on first and work down from there), the E/I, and the computer last. When powering down, the computer is to be turned off first, followed by the monitor, E/I, and peripherals. In addition, users are instructed to remove all disks from

7080-402: The TRS-80 was developed and marketed by Tandy/Radio Shack. The basic system can be expanded with up to 48 KB of RAM (in 16 KB increments), and up to four floppy disk drives and/or hard disk drives . Tandy/Radio Shack provided full-service support including upgrade, repair, and training services in their thousands of stores worldwide. By 1979, the TRS-80 had the largest selection of software in

7200-610: The VRAM, causing a short black line. This has little effect on normal BASIC programs, but fast programs made with assembly language can be affected. Software authors worked to minimize the effect, and many arcade-style games are available for the Tandy TRS-80. Because of bandwidth problems in the interface card that replaced the TV's tuner, the display loses horizontal sync if large areas of white are displayed. A simple half-hour hardware fix corrects

7320-439: The attention of more software developers. As the industry matured, the market for personal computers standardized around IBM PC compatibles running DOS , and later Windows . Modern desktop computers, video game consoles , laptops , tablet PCs , and many types of handheld devices , including mobile phones , pocket calculators , and industrial embedded systems , may all be considered examples of microcomputers according to

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7440-1282: The base software environment for the NonStop Servers, and has been extended to include support for Java and integration with popular development tools like Visual Studio and Eclipse . Later, Hewlett-Packard would split into HP and Hewlett-Packard Enterprise. The NonStop products and the DEC products would then be sold by HPE. A variety of companies emerged that built turnkey systems around minicomputers with specialized software and, in many cases, custom peripherals that addressed specialized problems such as computer-aided design , computer-aided manufacturing , process control , manufacturing resource planning , and so on. Many if not most minicomputers were sold through these original equipment manufacturers and value-added resellers . Several pioneering computer companies first built minicomputers, such as DEC , Data General , and Hewlett-Packard (HP) (who now refers to its HP3000 minicomputers as "servers" rather than "minicomputers"). And although today's PCs and servers are clearly microcomputers physically, architecturally their CPUs and operating systems have developed largely by integrating features from minicomputers. In

7560-453: The black-and-silver colors of the RCA CRT unit's cabinet for the TRS-80 units as well. Having spent less than US$ 150,000 on development, Radio Shack announced the TRS-80 (Tandy Radio Shack) at a New York City press conference on August 3, 1977. It cost US$ 399 (equivalent to $ 2,000 in 2023), or US$ 599 (equivalent to $ 3,000 in 2023) with a 12" monitor and a Radio Shack tape recorder;

7680-405: The business" and "never our large market". Although the press conference did not receive much media attention because of a terrorist bombing elsewhere in the city , the computer received much more publicity at Boston University 's Personal Computer Fair two days later. A front-page Associated Press article discussed the novelty of a large consumer-electronics company selling

7800-476: The cassette port and plugging an amplifier into the cassette "Mic" line. Most games use this ability for sound effects. An adapter was available to use Atari joysticks . User data was originally stored on cassette tape . Radio Shack's model CTR-41 cassette recorder was included with the US$ 599 package. The software-based cassette tape interface is slow and erratic; Green described it as "crummy ... drives users up

7920-455: The changing market by focusing entirely on the high-performance file server market, embracing a role within large LANs that appeared resilient. This did not last; Novell NetWare rapidly pushed such solutions into niche roles, and later versions of Microsoft Windows did the same to Novell. DEC decided to move into the large-computer space instead, introducing the VAX 9000 mainframe in 1989, but it

8040-577: The company had 500 Tandy Radio Shack Computer Centers. By 1979, when Radio Shack launched the business-oriented, and incompatible, TRS-80 Model II , the TRS-80 was officially renamed the TRS-80 Model I to distinguish the two product lines. After some exhibitors at the 1979 Northeast Computer Show were forced to clarify that their products bearing the TRS-80 name were not affiliated with Radio Shack, publications and advertisers briefly began to use "S-80" generically rather than "TRS-80" under scare of legal action, though this never materialized. Following

8160-447: The computer "probably the most important product we've ever built in a company factory". Unlike competitor Commodore —which had announced the PET several months earlier but had not yet shipped any—Tandy had its own factories (capable of producing 18,000 computers a month) and distribution network, and even small towns had Radio Shack stores. The company announced plans to be selling by Christmas

8280-418: The computer can be used to provide sounds. Radio Shack offered upgrades (double-density floppy controller, LDOS, memory, reliable keyboard with numeric keypad, lowercase, Level II, RS-232C) as late as its 1984 catalog. The Model I combines the mainboard and keyboard into one unit, which became a design trend in the 8-bit microcomputer era, although the Model I has a separate power supply unit. It uses

8400-576: The computer, company president Lewis Kornfeld admitted that they did not know if anyone would, but suggested that small businesses and schools might. Knowing that demand was very strong for the US$ 795 Altair—which cost more than $ 1,000 with a monitor—Leininger suggested that Radio Shack could sell 50,000 computers, but no one else believed him; Roach called the figure "horseshit", as the company had never sold that many of anything at that price. Roach and Kornfeld suggested 1,000 to 3,000 per year; 3,000

8520-469: The creation of an entire industry of minicomputer companies along Massachusetts Route 128 , including Data General , Wang Laboratories and Prime Computer . Other popular minis from the era were the HP 2100 , Honeywell 316 and TI-990 . Early minis had a variety of word sizes , with DEC's 12 and 18-bit systems being typical examples. The introduction and standardization of the 7-bit ASCII character set led to

8640-483: The data collection crews. Raytheon Data Systems RDS 704 and later RDS 500 were predominantly the systems of choice for nearly all the geophysical exploration as well as oil companies. At the launch of the MITS Altair 8800 in 1975, Radio Electronics magazine referred to the system as a "minicomputer", although the term microcomputer soon became usual for personal computers based on single-chip microprocessors . At

8760-401: The data. Then it is halted to rewind the tape and restart the load. Users were instructed to save multiple copies of a software program file, especially if audio tape cassettes instead of certified data tape was used. Automatic gain control or indicator circuits can be constructed to improve the loading process (the owner's manual provides complete circuit diagrams for the whole machine, including

8880-514: The definition given above. By the early 2000s, everyday use of the expression "microcomputer" (and in particular "micro") declined significantly from its peak in the mid-1980s. The term is most commonly associated with the most popular 8-bit home computers (such as the Apple II , ZX Spectrum , Commodore 64 , BBC Micro , and TRS-80 ) and small-business CP/M -based microcomputers. In colloquial usage, "microcomputer" has been largely supplanted by

9000-463: The drive controller board, but Tandy opted for a slightly more user-friendly technique where all four select pins on the drives are jumpered and the ribbon cable is missing the Drive Select line. Thus, the user does not need to worry about moving jumpers around depending on which position on the chain a drive was in. A standard flat floppy ribbon cable is usable on the Model I, in which case the drives

9120-407: The drives during power up or down (or else leave the drive door open to disengage the read/write head from the disk). This is because a transient electrical surge from the drive's read/write head would create a magnetic pulse that could corrupt data. This was a common problem on many early floppy drives. The E/I displays a screen full of garbage characters on power up and unless a bootable system disk

9240-729: The early "box of switches"-type microcomputers, the MITS Altair 8800 (1975) was arguably the most famous. Most of these simple, early microcomputers were sold as electronic kits —bags full of loose components which the buyer had to solder together before the system could be used. The period from about 1971 to 1976 is sometimes called the first generation of microcomputers. Many companies such as DEC , National Semiconductor , Texas Instruments offered their microcomputers for use in terminal control, peripheral device interface control and industrial machine control. There were also machines for engineering development and hobbyist personal use. In 1975,

9360-485: The early 1980s, such as DEC's VAX , Wang VS , and Hewlett-Packard's HP 3000 have long been discontinued without a compatible upgrade path. OpenVMS was ported to HP Alpha and Intel IA-64 ( Itanium ) CPU architectures, and now runs on x86-64 processors. Tandem Computers , which specialized in reliable large-scale computing, was acquired by Compaq in 1997, and in 2001 the combined entity merged with Hewlett-Packard . The NonStop Kernel-based NonStop product line

9480-554: The first 16 KB of memory space on the Model I. The remaining 48 KB of the 64 KB memory map space is available for program use, subject to the amount of physical RAM installed. Although the Z80 CPU can use port-based I/O, the Model I's I/O is memory-mapped aside from the cassette tape and RS-232 serial ports. The TRS-80 Model I keyboard uses mechanical switches that suffer from " keyboard bounce ", resulting in multiple letters being typed per keystroke. The problem

9600-642: The first available microprocessor-based microcomputer, the Micral N. The same year the company filed their patents with the term "Micro-ordinateur", a literal equivalent of "Microcomputer", to designate a solid state machine designed with a microprocessor. In the US the earliest models such as the Altair 8800 were often sold as kits to be assembled by the user, and came with as little as 256 bytes of RAM , and no input/output devices other than indicator lights and switches, useful as

9720-452: The form of RAM , and at least one other less volatile, memory storage device are usually combined with the CPU on a system bus in one unit. Other devices that make up a complete microcomputer system include batteries, a power supply unit, a keyboard and various input/output devices used to convey information to and from a human operator ( printers , monitors , human interface devices ). Microcomputers are designed to serve only one user at

9840-455: The foundation for all current versions of Microsoft Windows , borrowed design ideas liberally from VMS . Many of the first generation of PC programmers were educated on minicomputer systems. TRS-80 The TRS-80 Micro Computer System ( TRS-80 , later renamed the Model I to distinguish it from successors) is a desktop microcomputer developed by American company Tandy Corporation and

9960-644: The later 1970s. Most mini vendors introduced their own single-chip processors based on their own architecture and used these mostly in low-cost offerings while concentrating on their 32-bit systems. Examples include the Intersil 6100 single-chip PDP-8, DEC T-11 PDP-11, microNOVA and Fairchild 9440 Nova, and TMS9900 TI-990. By the early 1980s, the 16-bit market had all but disappeared as newer 32-bit microprocessors began to improve in performance. Those customers who required more performance than these offered had generally already moved to 32-bit systems by this time. But it

10080-473: The many separate components that made up the minicomputer's CPU with one integrated microprocessor chip . In 1973, the French Institut National de la Recherche Agronomique (INRA) was looking for a computer able to measure agricultural hygrometry . To answer this request, a team of French engineers of the computer technology company R2E, led by its Head of Development, François Gernelle , created

10200-440: The microcomputer market. Until 1982, the TRS-80 was the bestselling PC line, outselling the Apple II by a factor of five according to one analysis. The broadly compatible TRS-80 Model III was released in the middle of 1980. The Model I was discontinued shortly thereafter, primarily due to stricter Federal Communications Commission (FCC) regulations on radio-frequency interference to nearby electronic devices. In April 1983,

10320-423: The minicomputer class. Similar models using magnetic delay-line memory followed in the early 1960s. These machines, however, were essentially designed as small mainframes, using a custom chassis and often supporting only peripherals from the same company. In contrast, the machines that became known as minicomputers were often designed to fit into a standard chassis and deliberately designed to use common devices like

10440-526: The modern definition. Its introductory price of $ 18,500 (equivalent to $ 178,866 in 2023) places it in an entirely different market segment than earlier examples like the CDC 160. In contemporary terms, the PDP-8 was a runaway success, ultimately selling 50,000 examples. Follow-on versions using small scale integrated circuits further lowered the cost and size of the system. Its success led to widespread imitation, and

10560-404: The most expensive product Radio Shack previously sold was a US$ 500 stereo. The company hoped that the new computer would help Radio Shack sell higher-priced products, and improve its "schlocky" image among customers. Small businesses were the primary target market, followed by educators, then consumers and hobbyists; despite its hobbyist customer base, Radio Shack saw them as "not the mainstream of

10680-496: The move to 16-bit systems, with the late-1969 Data General Nova being a notable entry in this space. By the early 1970s, most minis were 16-bit, including DEC's PDP-11 . For a time, "minicomputer" was almost synonymous with "16-bit", as the larger mainframe machines almost always used 32-bit or larger word sizes. As integrated circuit design improved, especially with the introduction of the 7400-series integrated circuits , minicomputers became smaller, easier to manufacture, and as

10800-547: The new RISC approach promised performance levels well beyond the fastest minis, and even high-end mainframes. All that really separated micros from the mini market was storage and memory capacity. Both of these began to be addressed through the later 1980s; 1 MB of RAM became typical by around 1987, desktop hard drives rapidly pushed past the 100 MB range by 1990, and the introduction of inexpensive and easily deployable local area network (LAN) systems provided solutions for those looking for multi-user systems. The introduction of

10920-519: The older 8-inch (200 mm) diskettes with up to 1,155 KB. Near the end of the Model I's lifespan in 1982, upgrades were offered to replace its original controller with a double-density one. The first disk drives offered on the Model I were Shugart SA-400s which supported 35 tracks and was the sole 5 + 1 ⁄ 4 -inch drive on the market in 1977–78. By 1979, other manufacturers began offering drives. Models 3/4/4P uses Tandon TM-100 40-track drives. The combination of 40 tracks and double density gives

11040-489: The peripheral interfaces, with notes on operation). An alternative to using tape was data transmissions from the BBC 's Chip Shop programme in the UK, which broadcast software for several different microcomputers over the radio. A special program was loaded using the conventional tape interface. Then the radio broadcast was connected to the cassette tape interface. Tandy eventually replaced

11160-428: The pre-reboot session. Thus, for example, if a VisiCalc user suffers a spontaneous reboot, to recover data the user enters V + C + SPACE + ✶ at TRSDOS Ready, and Visicalc restores the previous computing session intact. The power button on the E/I is difficult to operate as it is recessed so as to guard against the user accidentally hitting it and turning it off while in use. A pencil eraser or similar object

11280-402: The problem. The graphics are displayed at a resolution of 64×16 character positions on a screen measuring 7.5 inches (19 cm) wide and 6.625 inches (16.83 cm) tall. Each character is composed of a 2×3 matrix of pixels, and corresponds to one byte of the 1 KB video memory used by the TRS-80. In each of those bytes, the first six bits control which pixel is displayed. The seventh bit

11400-439: The project but were told to emphasize cost savings; for example, leaving out lowercase characters saved US$ 1.50 in components and reduced the retail price by US$ 5 . The original US$ 199 retail price required manufacturing cost of US$ 80 ; the first design had a membrane keyboard and no video monitor. Leininger persuaded Roach and French to include a better keyboard, a monitor, datacassette storage, and other features requiring

11520-446: The same time, minis began to move upward in size. Although several 24 and 32-bit minis had entered the market earlier, it was DEC's 1977 VAX , which they referred to as a superminicomputer , or supermini, that caused the mini market to move en-masse to 32-bit architectures. This provided ample headroom even as single-chip 16-bit microprocessors like the TMS 9900 and Zilog Z8000 appeared in

11640-465: The software context, the relatively simple OSs for early microcomputers were usually inspired by minicomputer OSs (such as CP/M 's similarity to Digital's single user OS/8 and RT-11 and multi-user RSTS time-sharing system). Also, the multiuser OSs of today are often either inspired by, or directly descended from, minicomputer OSs. UNIX was originally a minicomputer OS, while the Windows NT kernel ,

11760-489: The term personal computer became generally used for microcomputers compatible with the IBM PC architecture ( IBM PC–compatible ). Minicomputer A minicomputer , or colloquially mini , is a type of smaller general-purpose computer developed in the mid-1960s and sold at a much lower price than mainframe and mid-size computers from IBM and its direct competitors . In a 1970 survey, The New York Times suggested

11880-464: The term " personal computer " or "PC", which specifies a computer that has been designed to be used by one individual at a time, a term first coined in 1959. IBM first promoted the term "personal computer" to differentiate the IBM PC from CP/M -based microcomputers likewise targeted at the small-business market, and also IBM's own mainframes and minicomputers. However, following its release, the IBM PC itself

12000-441: The term "calculator" because purchasing a "computer" required additional layers of purchasing authority approvals. The Datapoint 2200 , made by CTC in 1970, was also comparable to microcomputers. While it contains no microprocessor, the instruction set of its custom TTL processor was the basis of the instruction set for the Intel 8008 , and for practical purposes the system behaves approximately as if it contains an 8008. This

12120-539: The term "first minicomputer". Most computing histories point to the 1964 introduction of Digital Equipment Corporation 's (DEC) 12-bit PDP-8 as the first minicomputer. Some of this is no doubt due to DEC's widespread use of the term starting in the mid-1960s. Smaller systems, including those from DEC like the PDP-5 and LINC , had existed prior to this point, but it was the PDP-8 combination of small size, general purpose orientation and low price that puts it firmly within

12240-403: The time, microcomputers were 8-bit single-user, relatively simple machines running simple program-launcher operating systems like CP/M or MS-DOS , while minis were much more powerful systems that ran full multi-user, multitasking operating systems, such as VMS and Unix . The Tandem Computers NonStop product line shipped its first fully fault-tolerant cluster computer in 1976. Around

12360-516: The two men visited National Semiconductor in California in mid-1976, Homebrew Computer Club member Steve Leininger's expertise on the SC/MP microprocessor impressed them. National executives refused to provide Leininger's contact information when French and Roach wanted to hire him as a consultant, but they found Leininger working part-time at Byte Shop . Leininger was unhappy at National, his wife wanted

12480-417: The two-decade lifetime of the minicomputer class (1965–1985), almost 100 companies formed and only a half dozen remained. When single-chip CPU microprocessors appeared, beginning with the Intel 4004 in 1971, the term "minicomputer" came to mean a machine that lies in the middle range of the computing spectrum, in between the smallest mainframe computers and the microcomputers . The term "minicomputer"

12600-501: The ubiquitous Teletype Model 33 ASR. They usually took up one or a few 19-inch rack cabinets, compared with the large mainframes that could fill a room. In terms of relative computing power compared to contemporary mainframes, small systems that were similar to minicomputers had been available from the 1950s. In particular, there was an entire class of drum machines , like the UNIVAC 1101 and LGP-30 , that share some features of

12720-461: The video monitor and serves as its base, was offered instead. Standard features of the E/I are a floppy disk controller, Centronics parallel port for a printer, and an added cassette connector. Optionally, an extra 16 or 32 KB of RAM can be installed and a daughterboard with an RS-232 port. The 40-conductor expansion connector passes through to a card edge connector, which permits the addition of external peripherals such as an outboard hard disk drive,

12840-401: The wall", and the first issue of 80 Micro has three articles on how to improve cassette performance. It is sensitive to audio volume, and the computer gives only a crude indication as to whether the correct volume was set, via a blinking character on screen while data is loaded. To find the correct volume at first use, the load is started and the volume is adjusted until the TRS-80 picked up

12960-463: Was "the world’s first commercially produced minicomputer". It meets most definitions of "mini" in terms of power and size, but was designed and built to be used as an instrumentation system in labs, not as a general-purpose computer. Many similar examples of small special-purpose machines exist from the early 1960s, including the UK Ferranti Argus and Soviet UM-1NKh. The CDC 160 , circa 1960,

13080-485: Was a flop in the market and disappeared after almost no sales. The company then attempted to enter the workstation and server markets with the DEC Alpha , but was too late to save the company and they eventually sold their remains to Compaq in 1998. By the end of the decade all of the classic vendors were gone; Data General , Prime , Computervision , Honeywell , and Wang , failed, merged, or were bought out. Today, only

13200-464: Was a successful American chain of more than 3,000 electronics stores. Among the Tandy employees who purchased a MITS Altair kit computer was buyer Don French, who began designing his own computer and showed it to the vice president of manufacturing John V. Roach , Tandy's former electronic data processing manager. Although the design did not impress Roach, the idea of selling a microcomputer did. When

13320-525: Was described in Wayne Green 's editorial in the first issue of 80 Micro . Dirt, cigarette smoke , or other contamination enters the unsealed key switches, causing electrical noise that the computer detects as multiple presses. The key switches can be cleaned, but the bounce recurs when the keyboard is reexposed to the contaminating environment. Keyboard bounce only occurs in Model I computers with Level II BASIC firmware ; Level I BASIC has

13440-469: Was easier to learn and use than raw machine language, became a standard feature. These features were already common in minicomputers , with which many hobbyists and early produces were familiar. In 1979, the launch of the VisiCalc spreadsheet (initially for the Apple II ) first turned the microcomputer from a hobby for computer enthusiasts into a business tool. After the 1981 release by IBM of its IBM PC ,

13560-454: Was not a commercial success; production ceased shortly after introduction. In late 1972, a French team headed by François Gernelle within a small company, Réalisations & Etudes Electroniques (R2E), developed and patented a computer based on a microprocessor – the Intel 8008 8-bit microprocessor. This Micral-N was marketed in early 1973 as a "Micro-ordinateur" or microcomputer , mainly for scientific and process-control applications. About

13680-524: Was not long before this market also began to come under threat; the Motorola 68000 offered a significant percentage of the performance of a typical mini in a desktop platform. True 32-bit processors like the National Semiconductor NS32016 , Motorola 68020 and Intel 80386 soon followed. By the mid-1980s, high-end microcomputers offered CPU performance equal to low-end and mid-range minis, and

13800-417: Was re-ported from MIPS processors to Itanium-based processors branded as ' HP Integrity NonStop Servers'. As in the earlier migration from stack machines to MIPS microprocessors, all customer software was carried forward without source changes. Integrity NonStop continues to be HP's answer for the extreme scaling needs of its very largest customers. The NSK operating system, now termed NonStop OS , continues as

13920-492: Was selling three times as many computers as Apple Computer , with both companies ahead of Commodore. By 1981, InfoWorld described Radio Shack as "the dominant supplier of small computers". Hundreds of small companies produced TRS-80 software and accessories, and Adam Osborne described Tandy as "the number-one microcomputer manufacturer" despite having "so few roots in microcomputing". That year Leininger left his job as director for advanced research; French had left to found

14040-537: Was sold through their Radio Shack stores. Launched in 1977, it is one of the earliest mass-produced and mass-marketed retail home computers . The name is an abbreviation of Tandy Radio Shack, Z80 [microprocessor] , referring to its Zilog Z80 8-bit microprocessor. The TRS-80 has a full-stroke QWERTY keyboard, 4 KB dynamic random-access memory (DRAM) standard memory, small size and desk area, floating-point Level I BASIC language interpreter in read-only memory (ROM), 64-character-per-line video monitor , and

14160-441: Was the quantity the company would have to produce to buy the components in bulk. Roach persuaded Tandy to agree to build 3,500—the number of Radio Shack stores—so that each store could use a computer for inventory purposes if they did not sell. RCA agreed to supply the video monitor—a black-and-white television with the tuner and speakers removed—after others refused because of Tandy's low initial volume of production. Tandy used

14280-547: Was widely imitated, as well as the term. The component parts were commonly available to producers and the BIOS was reverse engineered through cleanroom design techniques. IBM PC compatible "clones" became commonplace, and the terms "personal computer", and especially "PC", stuck with the general public, often specifically for a computer compatible with DOS (or nowadays Windows). Monitors, keyboards and other devices for input and output may be integrated or separate. Computer memory in

14400-460: Was widely sold in kit form, along with an eighth 2102 chip. Later models came with the hardware for the lowercase character set to be displayed with descenders. With higher-density RAM chips and purpose-built monitors, higher-resolution crisp displays are obtainable; 80×24-character displays are available in the Model II, Model 4, and later systems. The Model I has no built-in speaker. Square-wave tones can be produced by outputting data to

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