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Tech History

Tandy’s PC Compatible Computers

Daniel Knight - 2015.12.19

In November 1983, Tandy entered the world of PC compatibles with one of the most powerful MS-DOS computers to date, the 8 MHz 80186-based Tandy 2000. This was long before IBM released the 6 MHz IBM Personal Computer/AT in August 1994.

Tandy 2000

Tandy Model 2000The Tandy 2000 was the first more-or-less PC compatible model Tandy released and its only PC compatible to be marked TRS-80. It originally retailed at US$2,999 and shipped with MS-DOS 2.0.

In fact, it was designed to be superior to the IBM PC. It was one of the few computers built around an 8 MHz Intel 80186 CPU, a full-fledge 16-bit chip, and it was much faster than 8088-based PCs and even outperformed the US$4,000 6 MHz IBM PC AT when it was introduced.

The Tandy 2000 was only partly PC compatible. It was better in several ways- it shipped with 128 KB of memory and supported up to 768 KB of RAM, had 8-color 640 x 400 graphics incompatible with standard CGA displays, and used 720 KB quad-density 5-1/4″ floppies (vs. 360 KB double-density). Its four expansion slots were proprietary and not compatible with IBM PC cards.

Radio Shack had a 10 MB hard drive upgrade available for the Tandy 2000.

Very few computers used the Intel 80816, and most of them were not quite IBM PC compatible. Other than the Tandy 2000, there were:

The IBM PC AT used the more advanced Intel 80286 and was released nine months after the Tandy 2000. Many of these computers ended up being used internally by Radio Shack retail stores.

Tandy 1000 ad - clearly superiorTandy 1000

The Tandy 1000 series was Radio Shack’s primary line of home computers, based on the more traditional 8088 and 8086 CPUs. It was designed to be compatible with the IBM PCjr‘s enhanced graphics, and the original Model 1000 arrived one year after the Tandy 2000.

Tandy went out of its way to paint the Tandy 1000 as “clearly superior” to the IBM PC, much as it had done in 1983 with the Tandy 2000. The difference was, the Model 1000 was very much IBM compatible, while the 2000 was not.

Keyboard for Tandy 1000 and 2000

Tandy had a unique keyboard layout that it introduced with the Model 2000 and used for the first two generations of the Tandy 1000 series. Compare this to the standard IBM PC keyboard with its F-keys on the left side:

IBM PC keyboard layout

Tandy was one of the first to move the F-keys to the top of the keyboard and group them, and also one of the first to put the arrow keys in an inverted-T formation. Those have since become standard features on almost every desktop keyboard.

The Tandy 1000 (1984) was specifically designed against the IBM PCjr, so it had 16-color PCjr graphics, a joystick port, 3-voice sound, and 128 KB of memory. Games compatible with the PCjr should run perfectly, and so should regular PC games. Over time, some games were optimized for PCjr/Tandy graphics. It ran at 7.16 MHz – 50% faster than the IBM PC – and it shipped with DOS 2.11 and DeskMate 1.0, Tandy’s desktop environment that had been ported over from TRSDOS.

Unfortunately for Tandy owners, its expansion slots were 11.5″ long instead of the industry standard 13″, making full sized cards incompatible.

Tandy used an edge connector for its parallel port and required use of a special parallel cable to work with standard printers.

A hard drive version known as the Tandy 1000 HD was available with a 10 MB or 20 MB hard drive.

Tandy 1000 EX and SX (1986)

The second generation included the Tandy 1000 SX, which looked a lot like the original Tandy 1000, and the US$1,000 1000 EX, which had everything built into a single device, included 256 KB of memory, and looked like a traditional home computer. The 5-1/4″ floppy drive was on the right side of the 1000 EX. Both models also ran at 7.16 MHz and could be dropped to 4.77 MHz PC speed using the Alt-S keystroke.

The 1000 EX uses special expansion cards called Tandy PLUS cards, because there just wasn’t room for full sized expansion cards in the compact case. This was the only way to boost memory to 640 KB. The 1000 EX shipped with DOS 2.11 and DeskMate.

The 1000 SX was an updated Tandy 1000 with 384 MB of onboard memory. It shipped with DOS 3.2 (a special version that would only boot Tandy PCs) and DeskMate II. The 1000 SX was the first Tandy with DMA (Direct Memory Access), which allows devices to access memory directly rather than going through the CPU.

Tandy 1000 HX and TX (1987)

Tandy 1000HXWith the Tandy 1000 HX, Radio Shack’s PCs got a built-in 3.5″ 720 KB floppy drive – mounted on the front for much easier access than the side-facing 5-1/4″ drive in the 1000 EX that it replaced. In fact, there was room for a second internal floppy drive.

The 1000 HX has DOS 2.11 and Personal DeskMate 2 built into ROM, so you can boot without using a floppy disk. Because of this, the HX boots much faster than any other Tandy computer of that era. You can run DOS 3.x on the 1000 HX, but it is not compatible with DOS 4.

The 1000 HX uses the same Tandy PLUS expansion cards as the 1000 EX and also shipped with 256 KB of memory on the system board.

The Tandy 1000 TX was the new powerhouse model with an 8 MHz 80286 CPU. Although it had 5-1/4″ drive bays, it came with a 720 KB 3.5″ floppy drive. With room for both sizes of floppy drive, the 1000 TX made it easy to transfer files from one type of disk to the other.

Although this is an 80286-based computer, it uses an 8-bit expansion bus and is not compatible with cards for the IBM AT 16-bit bus.

These were the last Tandy PCs with composite video output.

These were the last Tandy PCs to use the keyboard introduced with the Tandy 2000. From this point forward, Tandy PCs used the new industry standard extended keyboard layout.

On a personal note, I worked in a Radio Shack store during the 1988 holiday season when the 1000 TX was being blown out at $1,299 – and I sold one system every week.

Tandy 1000 SL and TL (1988)

With the 1000 SL and TL, Tandy worked to become more PC compatible. The most obvious difference was the 101-key extended keyboard, which replaced Tandy’s old layout. Tandy also updated case styling for the 1000 SL and TL. New video modes include 640 x 200 with 16 colors and Hercules 720 x 350 graphics for monochrome displays. There are five ISA expansion slots – even the ‘286-based models only have 8-bit expansion slots.

MS-DOS 3.3 and DeskMate 3 are in ROM. With DOS in ROM, these computers boot up very quickly. They can also run DOS 3.x, 5, and 6 from floppy or hard drive – and even Windows 2 and 3. MS-DOS 4 was generally problematic and is not recommended.

The 1000 SL uses the fully 16-bit 8086 CPU instead of the 8088, which uses an 8-bit data bus. (IBM chose the 8088 to keep production costs down when it released the IBM PC in 1981. Eight sockets and memory chips cost less than 16, and nobody knew if the PC would succeed.) The CPU runs at 8 MHz.

The 1000 SL has a single 5-1/4″ 360 KB floppy drive and 384 KB of memory. It was the last Tandy computer with two 5-1/4″ drive bays. Although you can install 640 KB of memory, 32 KB is dedicated to graphics, so a maximum of 576 KB can be used. This will prevent software that requires 640 KB from running.

The 1000 TL uses an 8 MHz 80286 CPU and shipped with 640 KB of memory. Like all 1988 and later models except the 1000 SL, the 1000 TL comes with a 3.5″ 720 KB floppy drive. There are bays for two 3.5″ drives and one 5-1/4″ drive.

As it ships, only 576 KB is available to programs. Memory can be expanded with a 128 KB upgrade. With this installed, video memory is moved, 640 KB is available to apps, and the rest of the upgrade becomes video memory.

The 1000 TL was the first 1000 series computer with a real time clock, so you no longer had to enter the date and time at startup or buy an accessory.

Tandy 1000 SL/2, TL/2, and TL/3

The 1000 SL/2 was pretty much a 1000 SL with a 3.5″ floppy drive instead of 5-1/4″ and 512 MB of memory from the factory instead of 384 MB.

The 1000 TL/2 is essentially a 1000 TL that has 4 available ISA expansion slots and a built-in XT IDE hard drive controller that is not compatible with AT IDE hard drives.

The 1000 TL/3 is a TL/2 with a 10 MHz 80286 CPU and a high density 1.44 MB floppy drive controller – although it ships with a double density 720 KB disk drive.

Tandy 1000 RL Series

Tandy moved to a slimline enclosure with the 1000 RL series. These models also have smaller mouse and keyboard ports that look like PS/2 ports but are not fully compatible. DOS and DeskMate remain in ROM for quick booting.

The base model is the 1000 RL, which has a 9.56 MHz 8086 CPU, making it about 20% more powerful than the 1000 SL and SL/2. Again, 512 KB of RAM is standard, and it can be upgraded to 768 MB with 640 KB available to programs and the rest used for video. The RL includes an XT IDE hard drive controller. The RL/HD is the same machine with a 20 MB hard drive.

The 1000 RLX has a 10 MHz 80286 and was the first Tandy with VGA graphics instead of the older Tandy graphics. The VGA graphics has its own 256 KB of memory, so no more stealing video RAM from system memory. It shipped with 512 KB of memory and is expandable to 1 MB. Another Tandy first – 384 KB of that can be accessed as extended memory.

The RLX shipped with a 1.44 MB high density floppy drive. The hard drive version came with 1 MB of RAM and a 20 MB hard drive.

1000 RSX: Tandy Does AT Class

With the top-end 1000 RSX, Tandy finally gave its users 16-bit ISA expansion slots. This was thus Tandy’s first AT class computer. It is powered by a 25 MHz 80386SX (the version of the 32-bit CPU that runs on a 16-bit data bus), has SVGA video, and includes two 16-bit expansion slots. It also has fully compatible PS/2 mouse and keyboard ports.

End of the Road for Tandy Computers

In 1993, Radio Shack sold its computer manufacturing business to AST Research, and in 1994 they agreed to carry AST computers in Radio Shack stores, bringing an end to the Tandy 1000 series.

AST didn’t understand the importance of the low end of the PC market and kept its focus on premium hardware. AST was in dire financial straits in the mid-1990s and was acquired by Samsung in 1996. Despite investments in AST, Samsung was unable to turn things around and eventually closed down AST.

Tandy Loses Its Way

In 1991, Tandy opened its first Computer City stores, which carried brands such as Apple, IBM, and Compaq – but not Tandy – in hopes of competing with CompUSA.

That didn’t work, and in June 1998, CompUSA acquired to Computer City chain. 50 stores were closed and the others became CompUSA stores. CompUSA closed most of its stores in 2007, and in 2012 it disappeared for good.

In 2015, RadioShack filed for Chapter 11 bankruptcy after 11 consecutive quarters of losses. The company had 4,297 stores in the United States in February 2015, of which 900 were run by independent dealers. As of March 31, 2015, there were only 1,743 stores left.

Further Reading

Tandy 2000

Tandy 1000 Series

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