Tandy 2000

Tandy 2000
Type Personal computer
Release date 1983 (1983)
Discontinued 1988
Operating system MS-DOS; Xenix
CPU Intel 80186 @ 8 MHz
Memory 128 KB - 768 KB (896KB w/mods)
Predecessor TRS-80 Z80-based series
Successor Tandy 1000 series

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.[1] By comparison, the IBM PC XT (introduced in March 1983) used the older 4.77 MHz 8088 processor, and the IBM PC AT (introduced in 1984) would later use the newer 6 MHz Intel 80286. Due to the 16-bit wide data bus and more efficient instruction decoding of the 80186, the Tandy 2000 ran significantly faster than other PC compatibles, and slightly faster than the PC AT. (Later IBM upgraded the 80286 in new PC AT models to 8 MHz.)

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.

The Tandy 2000 and its special version of MS-DOS supported up to 768 KB of RAM, significantly more than the 640 KB limit imposed by the IBM architecture.

The Tandy 2000 had both the "Tandy" and "TRS-80" logos on its case, marking the beginning of the phaseout of the "TRS-80" brand.

History

Ad in Byte magazine, July 1984, co-marketing MAI/Basic Four software

Two models were first introduced: a dual drive floppy-only model for $2750 and the 2000HD with a single floppy drive and a half-height 10 MB hard drive for $4250. The dual floppy model had 128 KB RAM and the hard drive 2000HD had 256 KB.

The computer received a lukewarm welcome by the market and the computer press because of its inability to run most popular MS-DOS applications. Though Radio Shack supported the machine with hardware add-ons and software tailored specially for it (including some of the most popular programs like Lotus 1-2-3), the computer failed to gain popular acceptance and was never developed further. Instead Tandy/Radio Shack turned its engineering efforts to the PCjr-compatible Tandy 1000, which proved more successful in the market.

The Tandy 2000 was marketed until 1988 with continual price cuts. Eventually they were closed out for $999 and the remaining unsold computers were converted into the first Radio Shack Terminals (which coincidentally had been one of the backup plans for the original TRS-80 Model I).

Specifications

Four card slots on the back could accept expansion boards without any need to open the case. Available expansion boards/cards included:[2]

Compatibility issues

The Tandy 2000 was nominally BIOS-compatible with the IBM XT, which allowed well-behaved DOS software to run 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, rendering the software incompatible with the Tandy 2000.

Graphics

The base Tandy 2000 supported only a text display mode. The text-mode address space was in a different location but third party memory-resident software hacks remedied this by copying the PC-compatible text-mode memory to the Tandy 2000's text space at a rate of 5-10 times per second. This caused a bit of choppiness in the display, but worked fairly well. It gave a very fast text display rate—often too fast to read, but a 'HOLD' key on the keyboard could be used to pause text output.

The display was upgradeable to support graphics via the Tandy 2000 Graphics Adapter, a circuit board that fitted into an expansion slot. It had its own connector for the monochrome VM-1 monitor (~$300); the connector in the rear of the computer cabinet for the text monitor was disabled with this option. The graphics resolution was 640x400 and supported bright text characters. The raster image for each text character was maintained in RAM and could be modified by the user. Color capability was provided by the Color Graphics Option, which was a set of chips that were inserted into the empty sockets on the monochrome Graphics Adapter provided for this purpose. Resolution was the same 640x400, non-interlaced, but up to sixteen colors were displayable on the Tandy CM-1 monitor (~$799). This was a particularly high-resolution and colorful display for its day. CGA compatibility was hit or miss.

There are only two non-Tandy monitors that will work with the Tandy 2000 graphics card, and they are long out of production. These were the original (1986–88) NEC Multisync and Multisync GS (GS for Grey Scale). The required horizontal scan frequency for the Tandy 2000 is 26.4 KHz. Modern flat-screen multisync computer monitors cannot sync at frequencies below 30 KHz. The CM-1 monitor is also digital RGB; all modern color monitors are analog only.

Media

The Tandy 2000 used quad-density 5.25" floppy disks formatted at 720k. This format type (80 track disks at the double-density bitrate) was not used by PC compatibles, although some CP/M machines and the Commodore 8050/8250 drives had them. Normal PCs of the time had 40 track double density floppy drives and could not read quad density due to the drive heads being too wide to read the narrower tracks. 1.2MB 5.25" drives (introduced on the IBM AT) could read quad density disks as they were 80-track and had thinner heads. Various utility programs for DOS existed that allowed nonstandard format types such as the Tandy 2000's disks to be read. Much like 1.2MB drives, the Tandy 2000 had problems reliably writing 360k PC disks due to the smaller heads not completely erasing the tracks and causing 40-track drives to become confused by residual magnetic signals on the outer edge of the track.

The floppy controller on the Tandy 2000 will accept 3.5" floppy drives, although as it does not support high density, they can only be used as 720k disks.

Keyboard

The keyboard was an entirely new design made expressly for the Tandy 2000. It would later be the same keyboard shipped with the Tandy 1000 and its successors.

The arrangement of the function keys was changed from that of the IBM PC/XT, which had ten on the left hand side of the keyboard in two columns of five. Tandy was one of the first PC manufacturers to change this to the modern arrangement of twelve function keys arranged horizontally across the top. IBM gave a nod to the new standard by making this its arrangement for the PC-AT keyboard.

Serial port

The serial port hardware was completely different from the PC/XT's. PC-compatible terminal emulation software had to either maintain strict BIOS usage of the serial hardware, or else use a FOSSIL driver, a software wrapper that virtualized the serial hardware (see also DEC Rainbow), allowing the terminal software to work on a wider variety of hardware.

Several terminal programs were available for the Tandy 2000, making it possible to log on to BBS's, e-mail, and other remote systems.

Operating system

The Tandy 2000 required a specific version of MS-DOS that would run only on this machine. Standard MS-DOS or PC DOS (for generic IBM-compatibles) would not run on a Tandy 2000. 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. The highest version of DOS that Tandy Corporation released for the Tandy 2000 was 2.11.03, with a few minor 3rd-party patches after the fact. A modified version of Windows 1.0 was able to run on the Tandy 2000.

The Microsoft BASIC interpreter was supplied with the computer. It was highly customized for the Tandy 2000 hardware, particularly its high resolution graphics.

Tandy/Radio Shack produced print advertising featuring Bill Gates of Microsoft extolling the superior performance of the Tandy 2000 and how it was advantageous in Microsoft's development of Windows 1.0.

Software

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 (office suite), DBase, MultiMate, Pfs:Write, AutoCAD, Lumena (from Time Arts) shareware office programs, and the complete line of Microsoft language products. Microsoft released a version of Xenix for the Tandy 2000 (used with Western Digital's ViaNet network card, distributed by Tandy).

Better BASIC for both the T2K and the PC was used to write BBS software for the T2K and later ported to the IBM-PC. Radio Shack's Deskmate was also used with the Tandy 2000 and the Tandy 1000.

The only version of Lotus 1-2-3 offered for the Tandy 2000 was Release 1A. This version used about 60 KB less memory than the later Release 2, which provided far greater macro programming facilities. Combined with the additional 128 KB of RAM available to a fully expanded Tandy 2000, it was possible to construct larger worksheets than later PC-compatibles running Release 2 (until the advent of machines with expanded memory). For nearly two years following its introduction, the Tandy 2000 was the top performer for running Lotus 1-2-3.

End of life

After Tandy dropped support of the Tandy 2000, a group of users formed the Tandy 2000 Orphans, with software reviews, software and hardware hacks, and a shareware/freeware repository. 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.

There was also a BBS based in Texas that had an extensive library of compatible software available for download; neither the BBS nor its web-based descendant is active today.

See also

References

  1. ↑ Frank Derfler (1984-06-18). "Tandy 2000: A superior machine and a good value". Infoworld. p. 71. Retrieved 2016-05-04.
  2. ↑ "1987 Tandy Computer Catalog" (PDF). Tandy Corporation. 1986. pp. 7,34. Retrieved 2016-05-06.

External links

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