The Tandy 2000 is a personal computer introduced by Radio Shack in September 1983 based on the 8 MHz Intel 80186 microprocessor running MS-DOS.

The Tandy 2000 was the company's first computer built around an Intel x86 series microprocessor; previous models used the Zilog Z80 and Motorola 6809 CPUs.

While touted as being compatible with the IBM XT, the Tandy 2000 was different enough that most existing PC software that was not purely text-oriented failed to work properly.

Many hardware and software companies were founded specifically to exploit IBM's and Microsoft's new presence as a standard-setter for small computers, and most other established manufacturers shifted focus to it as well.

[note 3] Tandy attempted to monopolize software and peripheral sales by not offering third-party products in company stores.

[3] Until the IBM PC was introduced, the nearest thing to an industry standard in small computers was CP/M-80;[note 4] no single manufacturer dominated.

By 1983 the IBM PC, and Tandy's discouraging of third-party products, had halved the company's market share and stopped profit growth.

[3] Tandy's motive for moving into the new MS-DOS domain was twofold: to capitalize on the new market, and to leverage sales opportunities afforded by their solid position in small computers.

Marketing management believed that many Tandy customers would prefer to stay with Tandy products when (inevitably, it seemed) they made the jump onto the burgeoning IBM/Microsoft bandwagon; it was figured that the company was well-positioned in this regard because of its large base of customers in both the consumer and business markets (with its Z80-based TRS-80 Models I/III/4 and 68000-based Models 12 and 16, respectively).

Tandy's large presence as a computer retailer, with several thousand Radio Shack stores throughout the US, was deemed an advantage as well.

This means that the software had to access the computer's hardware (particularly the video display) strictly through calls to the operating system's BIOS.

[note 7] Tandy's marketing department failed to appreciate that similar non-compatible computers from DEC, TI and Eagle were not successful.

[5] While admitting in 1984 that many MS-DOS programs did not support the computer, the company stated that "the most popular, sophisticated software on the market" was available, either immediately or "over the next six months".

[10][3] The Tandy 2000 received a lukewarm welcome by the market and the computer press because of its inability to run most popular MS-DOS applications.

Though the company supported the machine with hardware add-ons and software tailored specially for it (including bestsellers like Lotus 1-2-3 Release 1A and AutoCAD), the computer failed to gain popular acceptance and was never developed further.

[12] Eventually they were closed out for $999 and the remaining unsold computers were converted into Radio Shack store operations terminals (which, coincidentally, had been one of the backup plans for the original TRS-80 Model I).

Available expansion boards/cards included:[12] The Tandy 2000 was nominally BIOS-compatible with the IBM XT, so well-behaved DOS software ran on both platforms.

However, most DOS software of the time bypassed the operating system and BIOS and directly accessed the hardware (especially video and external ports) to achieve higher performance.

With clever programming the display's ability to present fine lines provided by the 640x400 screen resolution could be accessed in text mode even without the optional graphics board.

It was standard practice and Microsoft's expectation at the time that a customized version of MS-DOS would be prepared for each different machine, with I/O drivers designed for the hardware of that model.

Although IBM produced the Enhanced Graphics Adapter a little more than a year later (October 1984), the Microsoft BASIC interpreter would not support its greater color and resolution capabilities until 1988.

[20] Software packages that were released for the Tandy 2000 included WordPerfect 4.2 (WP5.1 could work with software patches), Lotus 1-2-3, Ashton-Tate's Framework, DBase, MultiMate, Pfs:Write, AutoCAD, Lumena (from Time Arts) shareware office programs, and the complete line of Microsoft language products.

MicroPro's Wordstar (versions 3.3 and 4.0 only) would run on the Tandy 2000 provided the user ran the WINSTALL installation utility and, when prompted for the type of video display to be used, selected "ROM BIOS".

This was customized to take advantage of the unique hardware of the computer, including its full 768K of RAM, high resolution color graphics, and two extra function keys.

The Tandy 2000's 720 KB floppy drives were a distinct advantage for running Lotus, because they were large enough to store even the largest worksheets on a single diskette.

It was discovered by amateur programmers that many commercial MS-DOS applications needed only minor modifications to function on the Tandy 2000's unique hardware.