1. History
    Early production  Competition  Bankruptcy 

2. Architecture
    Operating system  Software  Hardware  Peripherals 

3. Games

4. Reception

5. References

6. Further reading

7. External links

The Osborne 1 was the first commercially successful portable microcomputer, released on April 3, 1981, by Osborne Computer Corporation. It weighed 10.7 kg (24.5 lb), cost US$1,795, and ran the CP/M 2.2 operating system. Powered directly from a mains socket as it had no on-board battery, it was still classed as a portable device since it could be hand-carried when packed.

The computer shipped with a large bundle of software that was almost equivalent in value to the machine itself, a practice adopted by other CP/M computer vendors at the time.

Competitors such as the Kaypro II that used double density drives and had a larger 9" screen which could display 80×25 text quickly appeared.

History

The Osborne 1 was developed by Adam Osborne and designed by Lee Felsenstein. It was first announced in early 1981. Osborne, an author of computer books, decided he wanted to break the price of computers.

The Osborne's design was based largely on the Xerox NoteTaker, a prototype developed at Xerox PARC in 1976 by Alan Kay.^[1] The computer was designed to be portable, with a rugged ABS plastic case that closed up, and a handle.^[2] The Osborne 1 was about the size and weight of a sewing machine and was advertised as the only computer that would fit underneath an airline seat.^[3] It is now classified as a "luggable" computer when compared to later laptop designs such as the Epson HX-20.

Despite its unattractive design and heavy weight—the Osborne 1 was described as resembling "a cross between a World War II field radio and a shrunken instrument panel of a DC-3",^[4] and Felstenstein confessed that carrying two units four blocks to a trade show "nearly pulled my arms out of their sockets"^[5]—the computer amazed observers. BYTE wrote, "(1) it will cost $1795, and (2) it's portable!"^[6] ($1795 is the equivalent of ${{Inflation|US|1795|1981}} today.) The bundled word processing, spreadsheet, and other software alone was worth $1,500; as InfoWorld stated in an April 1981 front-page article on the new computer after listing the included software, "In case you think the price printed above was a mistake, we'll repeat it: $1795."^[7]{{r|dahmke198206}}

Osborne claimed that the new computer had a "significant price/performance advantage" but emphasized the price, stating that its performance was "merely adequate": "It is not the fastest microcomputer, it doesn't have huge amounts of disk storage space, and it is not especially expandable."{{r|hogan19810413}} Beyond the price, advertisements emphasized the computer's portability and bundled software.^[8] In the first eight months after April 1981, when the Osborne 1 was announced, the company sold 11,000 units.^[9] Sales at their peak reached 10,000 units per month.^[9]

Its principal deficiencies were a tiny {{convert|5|in|cm|adj=on}} display screen and use of single sided, single density floppy disk drives which could not contain sufficient data for practical business applications, and considerable unit weight. Adam Osborne decided to use single-sided disk drives out of concern about double-sided drives suffering head damage from rough handling. A single-density disk controller was used to keep costs down. As a result, the Osborne's floppy disks held a mere 90k.

Later Osborne models switched to double-density controllers and an upgrade was offered to owners of the original model Osborne 1.

In September 1981, Osborne Computer Company had its first US$1 million sales month. Sales of the Osborne 1 were hurt by the company's premature announcement of superior successor machines such as the Osborne Executive,^[10] a phenomenon later called the Osborne effect.

From 1982 to 1985, the company published The Portable Companion, a magazine for Osborne users.^[11]

Early production

The company initially had ten prototypes produced, as described in an email by Lee Felsenstein, the Osborne 1 designer.^[12]

Competition

The computer was widely imitated as several other computer companies began offering low-priced portable computers with bundled software. The Osborne's popularity was surpassed by the similar Kaypro II which had a much more practical {{convert|9|in|cm}} CRT that could display the standard 80 characters on 24 lines as well as double density floppies that could store twice as much data. Osborne Computer Corporation was unable to effectively respond to the Kaypro challenge until after the market window had closed and the day of the 8-bit, CP/M-based computer had ended.

In 1981, IBM released the 16-bit IBM PC which was significantly more powerful and expandable than 8-bit computers of the day.^[2] Following the release of the IBM-compatible Compaq Portable in 1983, the market for CP/M computers quickly plummeted and Osborne was unable to compete.

Bankruptcy

The Osborne Computer Company announced a successor to the Osborne 1 in 1982, the Executive model OCC-2 and in early 1983, the company announced the more advanced Osborne Vixen.^[2] This was a smaller machine with the keyboard permanently attached and serving as a stand. However, unable to beat its competition in the marketplace, Osborne Computer Corporation filed for bankruptcy in September 1983. It released the Osborne-4 (Vixen) in 1985, but it did not sell in great numbers.

Architecture

The 64 KB main memory was made of four rows of eight type 4116 dynamic RAM chips, each with 16,384 bits. Memory was shared, with 60 KB available for software and 4 KB reserved for video memory. No parity was provided and no provision for memory expansion existed on the motherboard. The boot program loader and significant parts of the BIOS were stored in a 4 kilobyte EPROM, which was bank-switched. A second EPROM was used as a fixed character generator, providing upper and lower case ASCII characters and graphic symbols; the character generator was not accessible to the CPU. The eighth bit of an ASCII character was used to select underlined characters. Serial communications was through a memory-mapped Motorola MC6850 Asynchronous Communications Interface Adapter (ACIA); a jumper on the motherboard allowed the MC6850 to be set for either 300 and 1200 baud or 600 and 2400 baud communications, but other bit rates were not available.^[16]

The floppy disk drives were interfaced through a Fujitsu 8877 disk controller integrated circuit, a second-source of the Western Digital 1793. The parallel port was connected through a memory-mapped Motorola MC6821 Peripheral Interface Adapter (PIA) which allowed the port to be fully bidirectional; the Osborne manuals also claimed the port implemented the IEEE-488 interface bus but this was rarely used. The parallel port used a card-edge connector etched on the main board, exposed through a hole in the case; any IEEE-488 or printer cable had to be specially manufactured for the Osborne.^[16]

The diskette drives installed in the Osborne 1 were Siemens FDD 100-5s (MPI drives were also used later), which were actually manufactured in California by GSI, a drive manufacturer that the German firm had purchased. They utilized a custom controller board that Osborne produced themselves, which among other things had a single connector for both the power and data lines. The FDD 100-5 proved to be quite trouble-prone as Osborne's quality control was lacking and many of the controller boards had soldering defects. In addition, the drive cable was not keyed and could be very easily installed upside-down, which would short out components in the computer and there were also problems with the drive head going past track 0 and getting stuck in place. The combo power/data cable also had a tendency of overheating.^[16]

The video system used part of the main memory and TTL logic to provide video and sync to an internal 5-inch monochrome monitor. The same signals were provided on a card edge connector for an external monitor; both internal and external monitor displayed the same video format.^[16]

The processor, memory, floppy controller, PIA, ACIA and EPROMs were interconnected with standard TTL devices.^[16]

The Osborne 1 had bank switched memory. Unusually for a system based on the Z80, all I/O was memory mapped, and the Z80 I/O instructions were only used to select memory banks. Bank 1 was "normal" mode, where user programs ran; this included a 4 kB area at the top of the address space which was video memory. Bank 2 was called "shadow". The first 4 kB of this address space was the ROM, and 4 kB was reserved for the on-board I/O ports. These were the disk controller, the keyboard, the parallel port PIA, the serial port ACIA, and a second PIA chip used for the video system. All memory above the first 16 KB was the same memory as Bank 1. This was the mode of the system on power up, because this was where the boot ROM was mapped. Bank 3 had only 4 kb by 1 bit of memory, used solely to hold the "dim" attribute of the video system.

Operating system

The computer ran on the then-popular^[3] CP/M 2.2 operating system. A complete listing of the ROM BIOS was available in the Osborne technical manual.^[13]

Software

The Osborne 1 came with a bundle of application software with a retail value of more than US$1500, including the WordStar word processor, SuperCalc spreadsheet, and the CBASIC and MBASIC programming languages.{{r|dahmke198206}} The exact contents of the bundled software varied depending on the time of purchase; for example, dBASE II was not included with the first systems sold.

Hardware

• Dual 5¼-inch, single-sided 40 track floppy disk drives ("dual density" upgrade available)
• 4 MHz Z80 CPU
• 64 kilobytes main memory
• Fold-down 69 key detachable keyboard doubling as the computer case's lid
• 5-inch, 52 character × 24 line monochrome CRT display, mapped as a window on 128 × 32 character display memory
• Parallel printer port configurable as an IEEE-488 port
• RS-232 compatible 1200 or 300 baud Serial port for use with external modems or serial printers

The Osborne 1 was powered by a wall plug with a switched-mode power supply, and had no internal battery. An aftermarket battery pack offering 1-hour run-time was available, and connected to the system through a front panel socket. Early models (tan case) were wired for 120 V or 240 V only.^[13] Later models (blue case, shipping after May 1982) could be switched by the user to run on either 120 V or 230 V, 50 or 60 Hz.^[13] There was no internal fan; a hatch at the top of the (blue) case could be opened for ventilation.

Peripherals

Additional peripherals were available by different third-party vendors at various times during the life of the Osborne 1.

• External Monochrome display. This used separate monochrome synch and video connections driven by the motherboard video circuitry.
• Parallel Dot matrix printer. Manufactured by Star
• 300 baud modem. Fit into a diskette storage pocket and powered from the motherboard.

A small set of aftermarket vendors offered several other upgrades to the basic model, including third-party double density disk drives, external hard disks, and a battery-backed RAM disk that fit in a disk storage compartment.

The Osborne corporation offered a "Screen-Pac" column upgrade that could be switched between original 52 column, 80 column and 104 column modes. Osborne 1 systems with the Screen-Pac upgrade have an RCA jack installed on the front panel to allow users to connect an external composite video monitor. ^[14] This modification was developed in Australia by Geoff Cohen and Stuart Ritchie and taken to the US by Stuart who turned up unannounced and sat outside Adam Osborne's office for two days. Osborne bought the mod as soon as they saw it and both of them worked with the Company to implement the mod. As a nod toward where it came from it was called the "Koala Project". Geoff went on to invent many other upgrades for Osborne's and was regarded as the Australian expert on the computers.

Games

Since, like most CP/M systems, the display of the Osborne did not support bit-mapped graphics, games were typically character based games, like Hamurabi or text adventures (the 1982 game Deadline, for example, packaged in a dossier type folder and came on two 5{{fraction|1|4}}" diskettes.). Compiled and MBASIC interpreted versions of Colossal Cave Adventure were available for the Osborne. Some type in games made good use of the Osborne's limited character-mode graphics.^[15]

Reception

In 1981, the daily Israeli newspaper Maariv, provided several Osborne 1 to its reporters. The computers were equipped with acoustic couplers. This configuration allowed a reporter to submit an article digitally directly from the field to the newsroom. Maariv used a localized version of Osborne 1 that supported Hebrew. {{cn|date=April 2018}} Freelance journalist David Kline praised the Osborne 1's durability, reporting in 1982 that the "damage inflicted by arrogant customs officers, airport police, vengeful Paris bellhops and opium-fogged Pakistani cabbies were entirely cosmetic".^[19] Stating that a computer that weighs 30 pounds "really isn't very portable", Creative Computing in 1984 concluded that "the main reason that the Osborne was a success was not that it was transportable, but that it came with a pile of bundled software".^[20]

References

Further reading

• Adam Osborne and John Dvorak (1984). Hypergrowth: the rise and fall of Osborne Computer Corporation. Idthekkethan Pub. Co. {{ISBN|0-918347-00-9}}.

External links

• Osborne 1
• At the Old Computer Museum
• {{youtube|ZUe6K3csS_4|Video of Osborne 1 computer}}

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