Tandy 1000

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Tandy 1000
Sabu with his Tandy 1000 Computer.jpg
Tandy 1000 EX's size was a little bigger than that of a household cat.
Type Personal Computer
Release date November 1984; 32 years ago (1984-11)[1]
Introductory price US$1,200 (equivalent to $2,766 in 2016)
Discontinued 1993

The Tandy 1000 was the first in a line of more-or-less IBM PC compatible home computer systems produced by the Tandy Corporation for sale in its RadioShack chain of stores.


In December 1983 an executive with Tandy Corporation, maker of TRS-80 computers, said about the new IBM PCjr home computer: "I'm sure a lot of people will be coming out with PCjr look-alikes. The market is big."[2]

Released in November 1984,[1] the $1,200 Tandy 1000 was designed as an inexpensive PC clone with enhancements compatible with the PCjr, but with a better keyboard.[3][4][5] "How could IBM have made that mistake with the PCjr?" an amazed Tandy executive said regarding its chiclet keyboard,[6] and another claimed that the 1000 "is what the PCjr should have been".[5]

Although the press saw the computer as Tandy, the former personal-computer leader, admitting that it could no longer focus on proprietary products in a market the IBM PC dominated, the 1000 sold more units in the first month than any other Tandy product and by early 1985 was its best-selling computer.[5][7] The 1000 included joystick ports like the PCjr, and copied its 16-color graphics and 3-voice sound, but not the PCjr ROM cartridge ports. Since IBM discontinued the PCjr soon after the release of the 1000, Tandy quickly removed mentions of the PCjr in its advertising while emphasizing its product's PC compatibility.[8]

Although Tandy initially marketed the 1000 as a business computer like the IBM PC, InfoWorld stated in 1985 that "the unwritten potential for the machine is in the elusive home computer market ... Tandy produced a real home computer".[7] The company claimed that the 1000 was "the first fully IBM PC-compatible computer available for less than $1000".[9] It helped the company obtain a 9.5% share of the US home-computer market in 1986, a year in which Tandy stated that half of its compatibles were purchased for the home.[10] In 1988 CEO John Roach disagreed with Apple counterpart John Sculley's rejection of the home market: "Let him deny it. He's the only other person that's well-represented in the home market, and if he wants to abandon it, it's all right with me."[11] Tandy also regained a significant share of the Apple-dominated educational market,[12] which the two companies had once equally shared.[13]

The 1000 and its many successors were successful unlike the PCjr, partly because it was sold in ubiquitous Radio Shack stores and partly because the computer was less costly, easier to expand, and almost entirely compatible with the IBM PC. The PCjr's enhanced graphics and sound standards became known as "Tandy-compatible". With its graphics, sound, and built-in joystick ports, the 1000 was the best computer for PC games until VGA graphics became popular in the 1990s.[8] Software companies of the era advertised their support for the Tandy platform;[14] 28 of 66 games that Computer Gaming World tested in 1989 supported Tandy graphics.[15]

Successors to the 1000 appended two or three letters to the name, after a space (e.g. Tandy 1000 EX, Tandy 1000 HX, Tandy 1000 SX, Tandy 1000 TX, Tandy 1000 RL, Tandy 1000 RLX). In a few instances, after these letters a slash was appended, followed by either a number or additional letters (e.g. Tandy 1000 TL/2, Tandy 1000 RL/HD). Although the original 1000 came in an IBM PC-like desktop case, some others used home-computer-style cases with the keyboard, motherboard and disk drives in one enclosure.

Design and architecture[edit]

Tandy 1000 computers were some of the first IBM PC clones to incorporate a complete set of basic peripherals on the motherboard using proprietary ASICs, the forerunner of the chipset. All Tandy 1000 computers featured built-in Tandy video hardware with color graphics (CGA-compatible with enhancements), enhanced sound (based on one of several variants of the Texas Instruments SN76496 sound generator), game ports compatible with those on the TRS-80 Color Computer, an IBM-standard floppy-disk controller supporting two drives, and a parallel printer port, all integrated into the motherboard. This is in addition to the hardware standard on the IBM PC, PC/XT, and PC/AT motherboards: keyboard interface, expansion slots, memory subsystem, interrupt controller, and math coprocessor socket. (Hard disks were high-end, not standard, equipment for home computers until the late years of the Tandy 1000 line, explaining the absence of an integrated hard-disk controller from most Tandy 1000 motherboards.) An IBM PC, XT or AT would require at least 4 expansion cards for similar hardware: one video graphics adapter card, one floppy-disk controller (FDC) card, one serial and parallel port card, and one sound card with a joystick port. (A third-party multi-IO card might merge the ports and FDC onto one card.) Therefore, the 5 XT slots of the original Tandy 1000, 1000 TX, 1000 SX, and similar models remained available for other hardware, making them equivalent or better than the 8 slots in IBM's XT and AT models (which had 8 slots because the original PC's 5 proved inadequate.)

By needing fewer wait states, the 1000's graphics hardware is as fast as the PC's while remaining compatible with both it and the PCjr. Like the PCjr, the 1000 uses up to 32K of system RAM for display memory. The computer's designers omitted a DMA because the PCjr does not have one, and they believed that those who needed it would add it with additional memory for the computer; they omitted the RS-232 port because all Tandy printers use the parallel port and, they believed, most customers would use internal modems.[16] The earlier models of the Tandy 1000 had a composite video output, and could be used with a color or monochrome composite monitor, or a TV with an RF modulator. The original 1000 and SX had a light-pen port. Unlike most PC clones, several Tandy 1000 computers had MS-DOS built into ROM and could boot in a few seconds. Tandy bundled DeskMate, a graphical suite of consumer-oriented applications, with various Tandy 1000 models.

The original line was equipped with the Intel 8088 CPU, which was later extended to faster clock speeds and also the 8086, 80286 and toward the end of the line with the RSX, 80386SX processors. Tandy 1000s (at least all early models) used Phoenix BIOS. Common models of the machine included the Tandy 1000, 1000 EX, 1000 HX, 1000 SX, 1000 TX, 1000 SL, 1000 RL, and 1000 TL. With the exception of the RLX and RSX, the Tandy 1000 machines are XT-class machines, which cannot support extended memory despite some models using 80286 processors, though expanded memory may be used on an 8-bit LIM EMS-compliant memory board. The RLX is an oddity, as it is an XT-class machine that supports 384 KB of extended memory, and the RSX is a fully AT-class machine which can support up to 9 MB of extended memory.

Hard disk drives[edit]

Tandy 1000 computers did not feature integrated hard-disk controllers until the release of the Tandy 1000 TL/2, which featured an on-board XT IDE controller. At this time hard disks were very expensive and needed only by high-performance users. However, it was possible to add a hard drive to most Tandy 1000 computers. Most of the desktop-type Tandy 1000 units could accept regular 8-bit ISA bus MFM, RLL and SCSI controllers like typical XT-class machines; however, care had to be taken when configuring the cards so that they did not cause conflicts with the on-board Tandy-designed peripherals.

For most Tandy 1000 models (other than the compact EX and HX) that did not come already equipped with a hard drive, Tandy offered hard disk options in the form of hardcards that were installed in one of the computer's expansion slots and consisted of a controller and drive (typically a 3.5-inch MFM or RLL unit with a Western Digital controller) mounted together on a metal bracket. Although this arrangement provided a neat physical coupling between the controller and the disk, single-sector internal transfers and dependence on the speed of the host machine to transfer data to memory meant that a trial-and-error approach was still needed to set the disk interleave correctly to ensure optimum transfer rates. Even then, transfer rates could be as low as 40 KB/s for 8088 and 8086 machines.

Starting with the Tandy 1000 TL/2, XT IDE controllers were integrated onto the motherboard. However, these were unable to support common AT IDE hard drives. The TL/2, TL/3, RL and RLX all used the XT IDE interface, where the later (and significantly upgraded) RSX was the first and only Tandy 1000 model computer to use a standard AT IDE interface. One option for contemporary users of these systems would be to install and use XT ISA CompactFlash adapters, which may be less expensive to acquire than vintage MFM/RLL or XT IDE hard drives and, potentially, the brackets needed to support them. This is also the most practical way to install a hard drive into a Tandy 1000 EX or HX, using an adapter cable that adapts the male PLUS-style connector to an 8-bit ISA card-edge slot.

Tandy slots and Hard cards[edit]

Tandy 1000ex/hx used a proprietary and small PLUS type expansion cards

Tandy aimed their 1000 series for the home and schools, and their chassis had a smaller footprint on the desktop than the IBM XT and clones, which were aimed for businesses. This smaller footprint comes at a price, the length of slots were only 10.5" not 13" as in the standard XT

Tandy used industry standard 8-bit XT ISA slots in their desktop models, including the 1000sx, tx, sl, tl series, but the actual length was limited to 10.5 inches or shorter, and not the industry standard XT length of 13 inches. 8-bit XT ISA cards would have to have a physical length shorter than 10.5" to be able to fit in the case. Many 8-bit cards that met this length requirement include modem cards, sound cards, graphics cards such as second generation EGA and VGA, network cards, 286 express etc. Some cards required the standard 13" length such as hard cards and EMS memory cards and multifunction cards would not fit in the tandy 1000 case.

Hard cards—a hard drive and drive controller combination that fits in a single ISA slot—were a way to add hard disk capacity while preserving the drive bays for disk drives and CD-ROMS. The first such hard card was released in October 1985 by Plus Development. However, these cards and similar designs from other companies were 13 inches long; since Tandy 1000 card slots are only 10.5" long and are 8-bit only, hard cards had to be certified as Tandy-compatible to verify whether they would work in a Tandy 1000 model such as the SX, TX, SL, and TL series.

Tandy offered its own 10.5" 20 MB hard card for $799. Several companies such as Zuckerboards offered hard cards that were 10.5" long and would work in Tandy 1000.

Hard cards usually must be placed in slot 1 in order to fit without cutting the metal frame and removing the case cover (which is also a way to accommodate a 13" card). The Tandy 1000 60 watt power supply is relatively low-powered, so an energy-efficient hard card is preferable.

The hard card is the only way to add a hard drive internally to a Tandy, while leaving the drive bays open to accept either 3.5" or 5 1/4" floppy, or even a CD-ROM in some models.

Tandy 1000 i/o and ports[edit]

Tandy 1000, SX, TX used a proprietary 8-pin round Din connector for the keyboard port that was compatible with the older TRS computers but not compatible with the IBM PC/AT or PS/2 standard. The SL/TL series were more compatible with IBM PS/2 keyboard and mouse standard. There are some scanline codes that differed between the Tandy 1000 and IBM PC/XT and at that can result in compatibility issues. Northgate offered a Tandy 1000 compatible keyboard.

Tandy 1000 used a proprietary 6-pin female round connector for the joystick port that on the SX/TX was adjacent to the keyboard port in the front of the computer. As with the keyboard, it was compatible with the older TRS-80 and Tandy color computer models. It was not compatible with the IBM standard 15-pin male game port and required a Tandy 1000 compatible joystick. Some PC-DOS games would not work with it, but most games made to work with Tandy 1000 graphics and sound do work. The Tandy 1000 mouse also fit in the game port. The Tandy 1000 mouse is not compatible with 9-pin serial or PS/2 mouse port, and some DOS software will not work with it, though Tandy 1000 specific software like deskmate does work.

The early Tandy 1000's used a non-standard card-edge parallel printer port rather than industry standard DB-25 printer port. It required a Tandy-1000 compatible printer cable to connect to a standard printer parallel port.

Tandy 1000TX and beyond used a proprietary floppy drive cable port, that also powered the floppy drive. It required a Tandy 1000 compatible floppy drive, though it may be possible to modify a floppy drive cable to make a standard floppy drive work

Tandy 1000 monitors[edit]

Tandy offered 2 color monitors specific for its Tandy 1000 computers. The budget model was the Tandy CM-5, which had a large dot pitch of 0.64 millimeters.[17] The premium model was the Tandy CM-11 with a dot pitch of 0.42 mm.[18] Both were 13 inch displays and had a power cable and a 9 pin RGB cable to attach to the Tandy CGA port. Both supported Tandy 320 by 200 16 color graphics. The more expensive CM-11 also supported the higher resolution 640 by 200 and a special proprietary Tandy enhanced 225 scan line for text display for clearer text. Normal CGA has only 200 scan lines. The CM-11 came in both black and white bezel.

Non-Tandy monitors that support CGA should work.

Tandy also offered monochrome monitors that support MDA and Hercules standard that also work with Tandy 1000.

Tandy 1000 keyboard[edit]

the original Tandy 1000, SX, EX, TX, HX used a proprietary keyboard and keyboard layout that was not compatible with PC/XT/AT standard then in use. The layout of the keyboard prefigured the IBM model M keyboard introduced with the IBM PS/2 series, with function keys arranged in a row at the top, instead of the left as in the PC and PC XT/AT. Later models of the Tandy 1000 series, such as the 1000 sl and tl and rl series used a keyboard more similar and compatible with the IBM ps/2 series keyboard connector and layout.

Tandy 1000 DOS and Windows and Deskmate[edit]

Tandy shipped PC's with their own customized version of MS-DOS, which are compatible with tandy graphics and keyboard. The most current version of MS-DOS for Tandy 1000 is DOS 3.22. There may be compatibility issues with later versions of DOS such as DOS 5 and DOS 6. Tandy 1000 is limited to 640k main memory, and non-Tandy versions of DOS often reduce the memory available for applications and games.

Tandy 1000 could work with Windows 1.0, 2.0 and 3.0 but not 3.1.

Tandy 1000 came shipped with Deskmate

Tandy 1000 printers[edit]

Radio Shack sold the Tandy DMP-130A dot matrix printers to go along with their Tandy 1000 line, along with compatible card-edged printer cable. This printer was sold at home budget prices. Radio Shack often offered a package bundle with a Tandy 1000 computer, CM-5 budget monitor and DMP-130A printer.


By 1993, changes in the market made it increasingly difficult for Tandy Corporation to make a profit on its computer line. Tandy Corporation sold its computer manufacturing business to AST Computers, and all Tandy computer lines were terminated. RadioShack stores then began selling computers made by other manufacturers, such as IBM[19] and Compaq.[20]


Creative Computing called the original Tandy 1000 "the machine IBM was too inept, incapable, or afraid to manufacture. It is sure to put a whopping dent not only into PCjr sales, but into sales of the PC 'senior' as well", favorably mentioning its low price, good PC-software compatibility, and bundled DeskMate ("you might never need another software package for your computer").[3] InfoWorld noted the 1000's low price ("fully one-third less than a comparably equipped IBM PC"), predicted that the computer was really intended for "the elusive home computer market", and speculated that "in retrospect it might have been the PCjr's final straw". The magazine called the 1000 "almost as fully IBM PC compatible as a computer can get", but gave DeskMate a mixed review and advised customers of the computer's inability to use full-length PC expansion cards. It concluded that "By making the 1000 inexpensive and adaptable" and including DeskMate, "Tandy produced a real home computer".[7]

80 Micro also approved of the 1000's PC compatibility and stated that the exterior design "gives it a feeling of quality and confidence". The magazine concluded that "Tandy's machine closely emulates the most basic functions of an IBM PC, and it does so at an affordable price ... along with the security of Tandy's substantial support network", but wondered if people would buy the 1000 if IBM lowered the price of the PC.[21] BYTE called the 1000 "a good, reasonably priced IBM PC clone that has most of the best features of the IBM PC and PCjr ... at current prices it is a very good alternative". It noted the high level of software compatibility and the good keyboard, and stated that DeskMate was "fairly good ... but a little extra programming work could have turned [it] into a much better program", noting that—for example—the word processor did not have a Move command. The magazine also mentioned the computer's short slots.[4] PC Magazine also noted the slots and criticized the Tandy 1000's fit and finish, but acknowledged the computer's low price and bundled hardware features.[22]

Selected models[edit]

Tandy 1000[edit]

The original Tandy 1000 was a large computer almost the size of the IBM PC, though with a plastic case over an aluminium lower chassis to reduce weight. The original Tandy 1000 featured a proprietary keyboard port (using an 8-pin DIN connector) along with 2 joystick ports (using 6-pin DIN connectors) on the front of the case. Unlike the IBM PCs, the T1K had a red hardware reset button located on the front panel directly beside the keyboard connector. (The user could also use the traditional CTRL-ALT-DEL to reset the machine). The rear featured an RGB monitor connector (a standard 9-pin female D-shell compatible with CGA/EGA monitors), an RCA-style composite video-out connector, a single RCA-style monophonic line-level audio connector, a light pen port, and an card-edge connector used to attach a parallel printer. The printer port followed the old Centronics standard and was not fully compatible with the parallel port found on PCs.

The original Tandy 1000 came standard with one internal 5.25" double-density floppy disk drive, with an additional exposed internal bay usable for the installation of a second 5.25" disk drive (available as a kit from RadioShack). The floppy drives used the old-fashioned method of selecting the drive number with jumpers instead of the IBM cable twist. 128 KB of memory was standard, with the computer accepting up to 640 KB of total memory with the addition of expansion cards.

MS-DOS 2.11, DeskMate 1.0, and a keyboard with the same layout as the Tandy 2000's were included with the computer. Like the PCjr, the Tandy 1000 motherboard did not supply DMA, but unlike that system, it could have DMA added with a memory expansion board. While the Tandy 1000 had three XT-compatible expansion slots, early Tandy memory upgrade boards took up two of the slots to get to 640 KB. Because the slots were 11 12 inches in length instead of the PC's 13 inches, full-length cards did not fit,[4] but reviewers noted that the many built-in hardware features reduced the need for cards.[22]

A later revision of the original Tandy 1000 model was the Tandy 1000A. This revision fixed bugs, scanned expansion cards for bootable ROMs, and added a socket for a math coprocessor.

Tandy 1000 HD[edit]

The original Tandy 1000 (and many other models), like most home computers sold at the time, did not have a hard disk drive. The Tandy 1000 HD was essentially an original Tandy 1000 with a hard disk option factory installed. The factory hard disk had a capacity on the order of 10 or 20 MB.

Tandy 1000 EX & SX[edit]

The Tandy 1000 EX was designed as an entry-level IBM-compatible personal computer. The EX was a compact computer that had the keyboard and 5.25" floppy drive built into the computer casing. The 5.25" drive was accessible on the right-hand side of the computer. The EX was marketed as a starter system for people new to computing, and sold for US$1,000.00 from RadioShack in December 1986. The EX and, later, the HX would be among the most popular of the Tandy 1000 line because of their (relatively) low price. The EX doubled the on-board memory to 256 KB.

The EX had a 7.16 MHz 8088 (capable of clocking down to 4.77 MHz) and one internal 5.25" floppy drive. An external drive could be connected to a port on the back. The EX itself supplied power to the external drive, so only Tandy's unit was usable with the EX. The external drive was the standard 360 KB 5.25 inch format; in 1988 a compatible 720 KB 3.5 inch model was offered. A useful feature for the EX and later systems was the ability to boot off either drive, as the drives could be logically swapped when the system booted, so that the drive that was normally drive B: became drive A:, and vice versa, and the drives remained swapped until the system was powered off or reset.

The Tandy 1000 SX was essentially an upgraded reissue of the original Tandy 1000 with the additional features of the EX. It used a 7.16 MHz 8088-2 processor, had 384k of memory (upgradeable to 640 KB on the motherboard), came with either one or two 5.25" internal floppy disk drives, had the light pen port (not a serial port) like the original Tandy 1000. Unlike the EX, it did not have a volume dial or headphone jack, but did have an adjustable potentiometer inside the system to control the volume of the internal speaker. The Tandy AX was a Tandy SX rebadged for sale in Wal-Mart stores. The SX/AX were drop-in compatible with NEC's V20 processor for a noticeable improvement in performance.

The 1000 EX came with MS-DOS 2.11 and Personal Deskmate on 5.25" 360kB diskettes. The 1000 SX came with MS-DOS 3.2 and Deskmate II on 5.25" 360kB diskettes. While Deskmate II used a text-based interface, Personal Deskmate used a graphical interface and also supported a mouse-like cursor using a joystick-mouse driver or a Tandy bus mouse. The MS-DOS was a version specialized for and only bootable on the Tandy 1000, as it would announce on the screen of any other PC-compatible one tried to boot with it; it included a version of BASICA (Microsoft's Advanced GW-BASIC) with support for the enhanced CGA graphics modes (a.k.a. Tandy Graphics or TGA) and three-voice sound hardware of the Tandy 1000.

The Tandy 1000 SX—and later the TX—were the first models in the Tandy 1000 line to have a built-in DMA controller. Adding the DMA chip improved the speed of diskette operations and IBM PC-compatibility of these earlier Tandy 1000 models and ensured that input from a serial port or keyboard would not be ignored during floppy drive access.

The SX was the first Tandy 1000 in which the built-in TGA video circuitry could be disabled via DIP switch. This was to permit the installation of an EGA or VGA video card in an expansion slot.

PLUS cards[edit]

The EX is upgradable via Tandy PLUS cards, and systems have bays for three. A PLUS card connector is electrically identical to an ISA slot connector, but uses a Berg-style 62-pin connector instead of a 62-contact ISA card-edge connector. RAM can be upgraded in the EX—and later the HX—to 640 KB, but requires a PLUS memory expansion card, which also provides DMA. Other PLUS cards could be installed to add serial ports, a 1200-baud modem, a clock/calendar and bus mouse board, or a proprietary Tandy network interface. RadioShack later sold an adapter card allowing installation of a PLUS card into a standard ISA slot, such as those in the larger Tandy 1000 models.

Tandy 1000 HX & TX[edit]

The Tandy 1000 HX was an updated version of the EX. It was mostly the same machine, but instead of one 5.25" drive bay, it had two 3.5" bays on the front panel, occupied by one 720 KB 3.5" floppy drive. This arrangement improved the computer's desk footprint over the EX, because no space was needed to the right of the machine to access the drive. It also had Tandy MS-DOS 2.11R in ROM, which could be accessed by starting the computer with no bootable disk present. By putting the basic elements of DOS and Deskmate in ROM and eliminating the memory test on startup, the HX booted quickly compared to other contemporary MS-DOS machines. System settings were changed with a setup program and were stored in EEPROM, and the system could be set to boot a program from the A: drive, boot to DOS or Personal Deskmate 2. The HX used the same 8088-2 and clock speeds as the EX, used the same PLUS cards, the same keyboard, and had the same ports as the EX. It also came with 256 KB of RAM on the motherboard. The HX's sound output had a distinctive grounding loop noise, which was clearly audible when the volume knob was turned up above 50%.[citation needed]

A Tandy 1000 HX, with a Tandy RGB monitor, an external 5.25-inch disk drive, joystick, and a Tandy DMP-133 dot matrix printer

The 1000 EX and HX did not come with a hard drive, nor was it available from Tandy as an option, although third-party vendors sold them. The design of the EX and HX did not make it easy to add a hard drive. On the back panel was a port allowing the connection of an external 360 KB 5.25" or 720 KB 3.5" floppy disk drive, available from Tandy. This made the HX unique among MS-DOS home computers in that three floppy drives were possible at once. For low-end users not requiring speedy disk access this often rendered a hard drive an unnecessary purchase. It was possible to fit an NEC V20 CPU to a Tandy 1000 EX or HX; this required disassembly of the computer.

The 1000 HX came with MS-DOS 2.11, modified to support up to three 720 KB drives and Personal Deskmate 2. Most versions of MS-DOS worked with the 1000 HX, including DOS 3.x, and some later versions. There was, however, a quirk in the DOS 4.0 environment that prevented that version of DOS from working with Tandy 1000 HX computers.

The Tandy 1000 TX was similar to the 1000 SX with its detached keyboard, unique parallel port edge connector and XT-style architecture in a slightly modified case. The major difference was the 80286 CPU clocked at 8 MHz. Unlike the SX (and other XT-class machines except the IBM XT 286), it featured a 16-bit-wide memory bus (as all 16 data lines from the 80286 are connected to the ROM/RAM memory and Chips and Technologies bus buffer), but the on-board peripherals and ISA slots were 8 bits wide. The TX's 80286 performed 16-bit transfers to and from memory (partially validating Tandy's claim that the 1000 TX offered AT-level performance), but DMA transfers and accesses to peripheral devices, including the video logic, were limited to 8-bit width.[23]

The TX had a 3.5" internal floppy disk drive mounted in a 5.25" bay with room for an optional second internal 3.5" or 5.25" floppy disk drive. It had ports for two joysticks in the front panel which included a volume control and an 18-inch headphone jack. The rear panel had the same ports as the 1000 SX except that an RS-232C serial port replaced the light-pen port. The memory size was 640 KB, with sockets for an additional 128 KB devoted to video frame buffering. The computer came bundled with Personal DeskMate 2.

Tandy 1000 SL, SL/2, TL, TL/2, TL/3[edit]

The Tandy SL and TL series of computers were updates of the SX and TX, respectively. In addition to offering redesigned cases, the machines offered a more integrated motherboard with improved graphics and sound capabilities while dropping composite video output. The memory bus and graphics controller interface were fully 16 bits wide, and the graphics controller now supported 640 × 200 × 16 resolution as well as a Hercules Graphics Card-compatible, 720 × 350 mode for monochrome monitors. The sound support now incorporated an 8-bit mono DAC/ADC, which was functionally similar to parallel port sound devices (such as the Covox Speech Thing and Disney Sound Source) but was extended to support DMA transfers, microphone input capability, and sampling rates up to 48 kHz. The SL/TL lines allowed the on-board floppy controller, parallel port and serial ports to be disabled, which the earlier models did not.

The SL and TL were also shipped with MS-DOS 3.3 and DeskMate 3 in ROM, and featured a serial EEPROM memory chip to store BIOS settings, which enabled similar functionality to today's CMOS NVRAMs so that startup options could be saved. By comparison, earlier Tandy 1000 models, with the exception of the HX, like IBM PC and PC/XT systems, used DIP switches and jumpers for startup configuration settings.) The machines could also run 'normal' MS-DOS 3.x, 5.x, and 6.x and Windows 2.x and 3.0 operating systems, although Windows was limited to real-mode operations. In common with many PC clones of the era, MS-DOS 4 was problematic and generally avoided.

1000 SL and SL/2[edit]

The SL's sound/reset satellite board

The Tandy 1000 SL and SL/2 feature an Intel 8086 processor running at 8 MHz. The SL came with 384 KB of RAM preinstalled, whereas the SL/2 offered 512 KB. Both machines could be expanded to 640 KB, although the graphics controller reserved a portion of this memory, yielding only 608 KB available the operating system, even on systems using add-in ISA graphic cards. The SL line had the mic/earphone ports, volume knob and reset button on a small satellite board, which had an LM386 audio power amplifier, a microphone input IC and a few small passives. There was also a jumper on the board to change the microphone input to a line-level output.[24] The SL series offered five 8-bit XT-compatible ISA slots, and did not come with pre-installed real-time clock chips, making them optional upgrades in the form of the plug-in Dallas DS1216E SmartWatch. The CPU could be replaced with NEC's V30 processor for a further increase in performance.

The SL is the only machine in the line that offers an upper 5.25" bay, and therefore the only model to offer two 5.25" bays, where the other models, including the SL/2 and the entire TL range, feature two upper 3.5" bays and one lower 5.25" bay. As a result, fitting a hard drive to an SL that already has the upper and lower 5.25" bays populated may require either the removal of one of the devices in those bays, or the installation of a hard disk card-style bracket which seats in one of the ISA slots.

1000 TL, TL/2 and TL/3[edit]

The Tandy 1000 TL and TL/2 used 8 MHz Intel 80286 processors, whereas the TL/3 used a 10 MHz 80286. These computers had 640 KB of memory preinstalled, with an option for an extra 128 KB for video frame buffering (just as in the 1000 TX). This extra 128 KB could only be used for and by the on-board video controller, so it was impractical to expand the on-board memory beyond 640 KB if a VGA graphics card was installed. Unlike the SL series machines, the TL machines came with the SmartWatch real-time clock logic built-in, which was powered by a removable 3-volt CR2032 button-cell battery on the motherboard.

The TL offered five 8-bit XT-compatible ISA slots, while the TL/2 and TL/2 offered four slots and an on-board 8-bit, XT IDE-compatible hard disk interface, which was not compatible with standard AT IDE hard drives. The TL series offered two upper 3.5" bays and one lower 5.25" bay. The TL/3 also offered a high-density floppy drive controller for 1.44 MB drives, though it shipped with a double-density 3.5" 720 KB drive.

Tandy 1000 RL, RL/HD, RLX, RSX[edit]

The Tandy 1000 RL/RLX/RSX series were slim-line desktop home computers. The RL and RL/HD featured a 9.56 MHz 8086 processor (surface-mounted, so no V30 upgrade was possible), 512 KB of RAM (expandable to 768 KB to provide 128 KB for video and 640 KB conventional memory), smaller keyboard and mouse ports (which were similar to the PS/2's ports but not 100% compatible), a DB-25 unidirectional parallel port instead of the edge-connector ports, and the SL's enhanced graphics and sound. A single half-size 8-bit expansion slot was available. Both the RL and RL/HD included a built-in XT IDE hard drive interface and the RL/HD came with a 20MB drive preinstalled. The RL/HD had a battery-backed real-time clock chip to store date and time information, which the RL lacked. These models also had MS-DOS and a portion of DeskMate in ROM, and could therefore boot much faster than many other computers on the market.

A Tandy 1000 RL running DeskMate (optional mouse not shown)

The RLX was the 'mid-range' offering of the RL line. It had a 10 MHz 286 (surface-mounted) and 512 KB of RAM, and unlike other 286-based Tandy 1000s, it supported 384 KB of extended memory when RAM was expanded to the maximum 1 MB. However, it was not a full AT-class machine, as it still had an 8-bit ISA bus (as with the RL, one half-size expansion slot) and only 8 IRQs and 4 DMA channels. While the three-voice sound chip and DAC were still present, Tandy video was dropped. The RLX had VGA instead, offering 256 kB of video memory and a maximum 640x480x16 (or 320x480x256) graphics resolution. The parallel port was bidirectional, a first for the Tandy 1000 series. The RLX had one 1.44 MB 3.5" floppy drive; an empty drive bay could host a second such drive. The hard disk RLX/HD came with a 20 MB hard disk and 1 MB RAM preinstalled. The hard disk occupied the empty drive bay, so this version supported only a single floppy drive.

The RSX offered a 25 MHz 80386SX processor, 1 MB RAM, two 16-bit ISA slots, AcuMos SVGA video, a bidirectional parallel port, and standard PS/2 keyboard and mouse ports. It was a full 386-class PC and could run Microsoft Windows 3.x. Two sockets for SIMM memory cards were provided. Only 1 MB or 4 MB SIMMs of the 9-chip type were supported, and if two were installed they had to be of like capacity. With two 4 MB SIMMs installed, the 1000 RSX could be expanded to 9 MB RAM (without using an ISA slot). The RSX/HD variant came with a 52 MB hard drive using an AT-compatible IDE interface; replacement hard drives up to 504 MB could be substituted. Because of the slimline case, only one hard drive could be installed alongside the 1.44 MB 3.5" floppy drive.[25][26]

The motherboard had a socket for the 80387SX math coprocessor. The RSX still retained the Tandy 1000 3-voice sound hardware and DAC, though the I/O address for the 3-voice sound chip was moved, rendering many games previously compatible with it unable to play music unless modified. The DAC could be used to emulate the Covox Speech Thing via MS-DOS device drivers for limited sound support. This worked with the game Chuck Yeager's Air Combat.[27]

Windows 3.xx sound device drivers were available that worked in Windows 95 (with full 9MB RAM) on Tandy 1000 RSX. The ACUMOS VGA graphics could be software-updated with Cirrus Logic BIOS (via MS-DOS driver) to allow VESA/SVGA to function in Windows 95, as the Windows 3.xx Tandy VGA drivers were insufficient for Windows 95.

Selected Tandy 1000-enhanced software[edit]

Major software publishers and makers of game and educational software, such as Sierra and Broderbund, offered software titles that specifically supported Tandy's unique and proprietary 16-color graphics, 3-voice sound, and other Tandy specific hardware features. These enhancements offer a superior graphics and sound experience for Tandy 1000 owners over standard DOS titles. Software that supported Tandy's graphics were typically labelled on the package as Tandy 1000/PCjr compatible. Many Tandy 1000 enhanced games are featured on youtube.

Although Tandy 1000s can run most DOS software, the below programs are known to specifically support Tandy 1000 enhanced features. These programs require DOS to run. Tandy shipped its own version of DOS. Tandy used the main memory for graphics, as a result most programs require 640k or 768k to run. The enhanced graphics and sound often tax the processor, so a 80286 processor or faster is recommended for best results.

There are also games and educational software that supports second generation Tandy 1000 graphics and sound, which offers 640 by 200 by 16 colors, and 8-bit DACs, found only on the 1000 sl/tl series. Examples of such software includes Mario's Typing Tutor, Star Trek, Freddy Pharkas: Frontier Pharmacist, Sargon Chess.


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