Micro Expander

Last updated
Micro Expander Model 1
Micro Expander logo.svg
Developer Lee Felsenstein
ManufacturerMicro-Expander, Inc.
Type Microcomputer
Release dateMay 1981;42 years ago (1981-05)
CPU Zilog Z80A at 4 MHz
Memory64 KB of RAM stock (expandable to up to 512 KB)
Predecessor Sol-20

The Micro Expander Model 1 (also known simply as the Expander [1] and sold in Europe as the PAL) is an S-100-based microcomputer introduced by Micro-Expander, Inc., in 1981. The computer was the brainchild of Lee Felsenstein, designer of the Sol-20, the first home computer. After his primary client and marketers of the Sol-20, Processor Technology, went out of business in 1979, Felsenstein founded a new company, Micro-Expander, Inc., in 1980. He gained the capital to sell his prototype of a successor to the Sol-20 as the Micro Expander Model 1 with help from some Swedish investors, primarily Mats Ingemanson, who was hired to market the computer.

Contents

Specifications

The Micro Expander Model 1 is a microcomputer with a built-in, full-sized keyboard complete with a numpad, two programmable function keys, and four cursor keys. [2] The Expander measures 18 by 18 by 3.5 inches (45.7 by 45.7 by 8.9 cm) and features a form factor identical to the Sol-20, however missing the walnut side panels. [3] The Expander is built on a single printed circuit board on which contains the microprocessor, ROM, the interrupt controller (which handles up to five simultaneous interrupt requests), the keyboard controller, an RS-232 serial I/O controller, a parallel interface controller, and circuitry to drive monochrome and color displays. The mainboard also contains a real-time clock, a polyphonic sound chip and internal beeper speaker, [4] and a cassette interface controller compatible with that of Radio Shack's TRS-80 line of microcomputers. [2]

The Expander runs off a Zilog Z80A microprocessor clocked at 4 MHz and features 64 KB of RAM stock, expandable to up to 512 KB. [5] Like the Sol-20, the Expander features the once-ubiquitous S-100 bus, with four S-100 expansion slots on the back of the machine, allowing a wide range of expansion cards for various applications (such as computer graphics, secretarial work, and process control) to be installed into it. [6] As stock, one of the four expansion cards is occupied by a 64-KB RAM card. Cards are allowed to be piggybacked onto one another owing to added internal bus structures, potentially allowing more than four expansion cards to be installed at once. [7]

The Expander could run any standalone software, programming language interpreter, and operating system written for the Z80. CP/M and MP/M were the most common operating systems for Z80 machines at the time of its release. [6] Micro Expander shipped the computer with a copy Microsoft's 24-KB BASIC interpreter on 5.25-inch floppy disk as well as a copy of their 10-KB cassette BASIC interpreter on microcassette. [8] A 4-KB machine code monitor is also included on a ROM on the mainboard. [9]

The Expander can generate video in one of four modes: monochrome text, monochrome graphics, color graphics, and color text. In monochrome text mode it can display 80 columns by 24 lines of text; its character generation chip supports both uppercase and lowercase text. In monochrome graphics mode it can display one screen of 160 by 72 pixels in either black or white. In color graphics mode, it can display one screen of 80 by 72 pixels, with 256 simultaneous colors available. In color text mode it can display 50 columns by 24 lines of text, with each character cell able to have its background and text set to any of the 256 available colors. [2] By InfoWorld 's estimation, the Expander was the first low-cost S-100 system to have built-in color graphics as a standard feature. [7]

Development and release

The Micro Expander was the brainchild of Lee Felsenstein, designer of the Sol-20, the first pre-assembled microcomputer with a built-in keyboard and external video output—in essence, the first home computer. Processor Technology, who manufactured and marketed the Sol-20, commissioned Felsenstein for the blueprints of a successor to their VDM-1, the first video card for the S-100 bus. [2] Before the design was production-ready, however, Processor Technology abruptly went out of business in May 1979, leaving Felsenstein in a vulnerable position, having recently leased an 800-square-foot shop in Berkeley, California, and now lacking his biggest client and primary source of income. [10] A businessman acting on behalf of a group of investors, including Adam Osborne, inquired Felsenstein about developing a successor to the Sol-20 but was put off by Felsenstein's long list of improvements he deemed necessary to carry the Sol-20 design into the next decade. By way of Bill Etra, however, he soon met a Swedish businessman named Mats Ingemanson, who asked Felsenstein to design a computer similar to the Apple II but that was capable of running software for the Z80, including CP/M, and that could display graphics compatible with Radio Shack's TRS-80. [11] The result of their collaboration was the Micro Expander Model I, first announced in September 1980 and unveiled at the West Coast Computer Faire in April 1981. [12] According to Ingemanson, the Micro Expander was essentially "what the Sol would have become." [13]

Felsenstein incorporated Micro-Expander, Inc., from Chicago, Illinois, to market the device in the United States and Europe. [14] The company was financially backed up by a number of investors in Sweden including Ingemanson but manufactured in the United States. Felsenstein hired Ingemanson as the head of marketing for Micro-Expander, Inc., [15] while Bob Marsh of Processor Technology was hired as head of production. [11] In Europe, the computer was sold as the PAL, named so after the European analog color broadcasting encoding standard of the same name, PAL. [16] Initially slated for a fourth-quarter 1980 release, the company instead released the Expander in May 1981, [17] as the company's distribution network was not yet set up until earlier in April. [7] Their original target street price for the Expander was $1,500 in 1980; this was later revised to just under $2,000 in 1981. [1]

Despite including Microsoft BASIC on disk, the Micro Expander was released without any specific disk hardware developed for it. Ingemanson explained that such a disk system would eventually be released, although he expressed that the company was hesitant to disrupt the existing ecosystem of compatible S-100 floppy disk hardware. [7]

The company projected sales of a few hundred units of the Expander between May and July 1981. Ingemanson was optimistic about selling thousands of units monthly by fall 1981. [7] However, Felsenstein in 1996 estimated that only about 200 units of the Expander were ever produced. [11] The company later released a 16-bit upgrade board for the Expander in June 1982. [18] The Expander remained on sale into at least 1983; [19] Micro-Expander, Inc., went defunct in January 1987. [20]

With Adam Osborne and his Osborne Computer Corporation, Felsenstein designed the far more successful Osborne 1 in 1981. [21]

Citations

  1. 1 2 Tebbutt 1981, p. 76.
  2. 1 2 3 4 Ahl 1981, p. 106.
  3. ↑ Canon 1980, p. 1; Sokolow 1981, p. 1.
  4. ↑ Anon. 1981f, p. 198; Ahl 1981, p. 106.
  5. ↑ Anon. 1981a, p. 94; Anon. 1981f, p. 198; Anon. 1981e, p. 122.
  6. 1 2 Anon. 1981c, p. 16; Anon. 1981e, p. 122.
  7. 1 2 3 4 5 Hogan 1981, p. 34.
  8. ↑ Anon. 1981b, p. 25.
  9. ↑ Anon. 1981f, p. 198.
  10. ↑ Ahl 1981, p. 106; Crosby 1996, pp. 19–20.
  11. 1 2 3 Crosby 1996, p. 20.
  12. ↑ Canon 1980, p. 1; Hogan 1981, p. 1.
  13. ↑ Hogan 1981, p. 1.
  14. ↑ Anon. 1981d, p. 70; Anon. 1981c, p. 16.
  15. ↑ Canon 1980, p. 1.
  16. ↑ Anon. 1981c, p. 16; Crosby 1996, p. 20.
  17. ↑ Anon. 1981b, p. 26.
  18. ↑ Scannell 1982, p. 6.
  19. ↑ Anon. 1983, p. 34.
  20. ↑ OpenCorporates n.d.
  21. ↑ Henderson 2020, p. 88.

Related Research Articles

<span class="mw-page-title-main">IBM Personal Computer</span> Personal computer model released in 1981

The IBM Personal Computer is the first microcomputer released in the IBM PC model line and the basis for the IBM PC compatible de facto standard. Released on August 12, 1981, it was created by a team of engineers and designers directed by William C. Lowe and Philip Don Estridge in Boca Raton, Florida.

<span class="mw-page-title-main">TRS-80</span> 1977 microcomputer by Tandy Corporation

The TRS-80 Micro Computer System is a desktop microcomputer launched in 1977 and sold by Tandy Corporation through their Radio Shack stores. The name is an abbreviation of Tandy Radio Shack, Z80 [microprocessor]. It is one of the earliest mass-produced and mass-marketed retail home computers.

<span class="mw-page-title-main">Osborne 1</span> Early portable microcomputer

The Osborne 1 is the first commercially successful portable computer, released on April 3, 1981 by Osborne Computer Corporation. It weighs 24.5 lb (11.1 kg), cost US$1,795, and runs the CP/M 2.2 operating system. It is powered from a wall socket, as it has no on-board battery, but it is still classed as a portable device since it can be hand-carried when the keyboard is closed.

<span class="mw-page-title-main">Rainbow 100</span> DEC microcomputer

The Rainbow 100 is a microcomputer introduced by Digital Equipment Corporation (DEC) in 1982. This desktop unit had a monitor similar to the VT220 and a dual-CPU box with both 4 MHz Zilog Z80 and 4.81 MHz Intel 8088 CPUs. The Rainbow 100 was a triple-use machine: VT100 mode, 8-bit CP/M mode, and CP/M-86 or MS-DOS mode using the 8088. It ultimately failed to in the marketplace which became dominated by the simpler IBM PC and its clones which established the industry standard as compatibility with CP/M became less important than IBM PC compatibility. Writer David Ahl called it a disastrous foray into the personal computer market. The Rainbow was launched along with the similarly packaged DEC Professional and DECmate II which were also not successful. The failure of DEC to gain a significant foothold in the high-volume PC market would be the beginning of the end of the computer hardware industry in New England, as nearly all computer companies located there were focused on minicomputers for large organizations, from DEC to Data General, Wang, Prime, Computervision, Honeywell, and Symbolics Inc.

Ohio Scientific, Inc., was a privately owned American computer company based in Ohio that built and marketed computer systems, expansions, and software from 1975 to 1986. Their best-known products were the Challenger series of microcomputers and Superboard single-board computers. The company was the first to market microcomputers with hard disk drives in 1977.

<span class="mw-page-title-main">Video Genie</span> Series of computers produced by Hong Kong-based manufacturer EACA during the early 1980s

Video Genie is a discontinued series of computers produced by Hong Kong-based manufacturer EACA during the early 1980s. Computers from the Video Genie line are mostly compatible with the Tandy TRS-80 Model I computers and can be considered a clone, although there are hardware and software differences.

<span class="mw-page-title-main">Apple II Plus</span> Second model of the Apple II series of personal computers by Apple Computer

The Apple II Plus is the second model of the Apple II series of personal computers produced by Apple Computer. It was sold from June 1979 to December 1982. Approximately 380,000 II Pluses were sold during its four years in production before being replaced by the IIe in 1983.

<span class="mw-page-title-main">Research Machines 380Z</span> British 8-bit microcomputer, 1977 to 1985

The Research Machines 380Z was an early 8-bit microcomputer produced by Research Machines in Oxford, England, from 1977 to 1985.

<span class="mw-page-title-main">Sol-20</span> 8-bit computer introduced in 1976

The Sol-20 was the first fully assembled microcomputer with a built-in keyboard and television output, what would later be known as a home computer. The design was the integration of an Intel 8080-based motherboard, a VDM-1 graphics card, the 3P+S I/O card to drive a keyboard, and circuitry to connect to a cassette deck for program storage. Additional expansion was available via five S-100 bus slots inside the machine. It also included swappable ROMs that the manufacturer called 'personality modules', containing a rudimentary operating system.

George Morrow was part of the early microcomputer industry in the United States. Morrow promoted and improved the S-100 bus used in many early microcomputers. Called "one of the microcomputer industry's iconoclasts" by Richard Dalton in the Whole Earth Software Catalog, Morrow ran his own computer business, Thinker Toys, Inc., later Morrow Designs. He was also a member of the Homebrew Computer Club.

The Z-100 computer is a personal computer made by Zenith Data Systems (ZDS). It was a competitor to the IBM PC.

<span class="mw-page-title-main">BBC Micro</span> Series of British microcomputers by Acorn

The British Broadcasting Corporation Microcomputer System, or BBC Micro, is a series of microcomputer designed and built by Acorn Computers Limited in the 1980s for the Computer Literacy Project of the BBC. Designed with an emphasis on education, it was notable for its ruggedness, expandability, and the quality of its operating system. An accompanying 1982 television series, The Computer Programme, featuring Chris Serle learning to use the machine, was broadcast on BBC2.

Realistic Controls Corporation (NCC), later Nylac Computer Corporation and Archives, Inc., was an American computer company based in Davenport, Iowa, founded in 1974.

<span class="mw-page-title-main">APC series</span>

The APC was a series of business microcomputers released outside of Japan by the NEC Corporation. The series comprised the APC, the APC II and APC III, international versions of models from the Japanese NEC N5200 series(jp).

<span class="mw-page-title-main">Sony SMC-70</span> A microcomputer that was produced by Sony and released in September 1982

The SMC-70 is a microcomputer that was produced by Sony and released in September 1982. The system was initially released for general office use in the United States, with the SMC-70G and SMC-70GP designed for professional video generation, for example in cable television applications, and digital video effect generation.

The Humdinger Color Computer was an 8-bit home computer introduced in 1983 by Venture Micro, Inc., of Cupertino, California.

<span class="mw-page-title-main">Dimension 68000</span> Microcomputer introduced by the Micro Craft Corporation in 1983

The Dimension 68000 is a microcomputer introduced by the Micro Craft Corporation in 1983 that sought to emulate the Apple II, the IBM PC, and various CP/M-centric computers through a family of coprocessor expansion cards and emulation software. The Dimension 68000 can also run as a standalone computer based on the Motorola 68000 from which it gets its namesake. The computer is mostly the brainchild of Mike Carpenter, a former executive of a scientific instrument manufacturer who incorporated Micro Craft in Dallas, Texas, to develop the Dimension 68000. It had a market lifespan of three years and received mixed, mostly positive, reception from the technology press. Criticism was leveled at the $6,250 price tag for the computer with the full deck of coprocessor cards, as well as the extent of the emulation power of those cards.

The Stratos was a Z80-based microcomputer introduced by Symbiotic Systems, Inc., in 1981.

Gnat Computers, Inc. was an American computer company based in San Diego, California, founded in 1976. The company was an early developer of microcomputers and one of the first—if not the first—to license the CP/M operating system from Digital Research. They released various computer hardware, including two microcomputer systems, before they were acquired by business partner Data Technology Industries, Inc., in 1983.

Terak Corporation was an American computer company based in Scottsdale, Arizona. The company was among the first to market graphical workstations, with their most successful being the Terak 8510/a in 1977. After going public in 1983, the company was acquired by Sanders Associates, who placed it under their CalComp division.

References

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.