Tandy 1000

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File:Sabu with his Tandy 1000 Computer.jpg
Tandy 1000 EX's size was a little bigger than that of a household cat.

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.

Overview

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."[1]

Released in November 1984,[2] 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]:{{{3}}}[5]:{{{3}}} "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]:{{{3}}}[7]:{{{3}}} 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 1000's release, Tandy quickly removed mentions of the PCjr in its advertising while emphasizing the 1000's PC compatibility.[8]:{{{3}}}

The machine and its many successors were successful unlike the PCjr, partly because the Tandy 1000 was sold in ubiquitous Radio Shack stores and partly because it 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;[9] 28 of 66 games that Computer Gaming World tested in 1989 supported Tandy graphics.[10]

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

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, DMA, 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.)

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

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 do not cause conflicts with the onboard 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" 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 40kB/s for 8088 and 8086 machines.

Starting with the Tandy 1000 TL/2, XT IDE controllers were integrated onto the motherboard. However, these are 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.

Retirement

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 Compaq.

Reception

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]:{{{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.[11] 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.[12]

Selected Tandy 1000 Models

Tandy 1000

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. 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 edge-card 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 1⁄2 inches in length instead of the PC's 13 inches, full-length cards did not fit,[4]:{{{3}}} but reviewers noted that the many built-in hardware features reduced the need for cards.[12]:{{{3}}}

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

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

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 $1000.00 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 256kB.

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. A useful feature for the EX and later systems is the ability to boot off either drive, as the drives can be logically swapped when the system boots, so that the drive that is normally drive B: becomes drive A:, and vice versa, and the drives remain swapped until the system is powered off or reset.

The EX was upgradable by Tandy PLUS cards, and system had bays for three. The PLUS cards' connector was electrically identical to the ISA slot connector, but used a BERG-style 62-pin connector instead of a 62-contact ISA card edge connector. The RAM could be upgraded in the EX and later the HX to 640kB, but required a PLUS memory expansion card. This card also provided DMA. Other PLUS cards could be installed to add serial ports, a 1200 baud modem, a clock/calendar and bus mouse board and a proprietary Tandy network interface.

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 are 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" 360 kB diskettes. The 1000 SX came with MS-DOS 3.2 and Deskmate II on 5.25" 360 kB 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.

Tandy 1000 HX & TX

The Tandy 1000 HX was an updated version of the EX. It was mostly the same machine, but had two 3.5" floppy bays instead of one 5.25" bay, and came with a 720kB floppy 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 will boot very quickly compared to other contemporary Tandy machines. System settings changed with a setup program and were stored via an EEPROM, and the system could be set to boot a program from the A: drive, boot to DOS or Personal Deskmate 2. The HX uses the same CPU and clock speeds as the EX, uses the same PLUS cards, keyboard and has the same ports as the EX. It also came with 256kB of RAM on the motherboard. The HX's sound output has a distinctive grounding loop noise, which was clearly audible when the volume knob was turned up above 50%.[citation needed]

File:Tandy1000HX tweaked.jpg
A Tandy 1000 HX, with a Tandy RGB monitor, an external 5.25 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 a number of third party vendors sold them. The design of the EX and HX did not make it easy to add a hard drive, however. RadioShack eventually sold an adapter card that allowed the installation of a "Plus Card" into a standard ISA slot, such as those in the larger Tandy 1000 models. On the back of the machine there was a port which allowed a user to connect an external 360 kB 5.25" or 720 kB 3.5" floppy disk drive unit, available from Tandy. It is possible to fit an NEC V20 to a Tandy 1000 EX or HX; however, this may require disassembly of the computer.

The 1000 HX came with MS-DOS 2.11, modified to support 720kB 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 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 very similar to the Tandy 1000 SX, having an external keyboard and similar casing. The major difference was the use of an 80286 CPU; otherwise, it was nearly identical to the SX, including its unique parallel port edge connector and XT-style architecture. Unlike the SX (and most XT-class machines in general), it features 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 onboard peripherals are 8-bit wide. This means that the TX's 80286 can perform 16-bit transfers to and from memory (partially validating Tandy's claim that the 1000 TX offered AT-level performance), but DMA transfers and access to peripheral devices, including the video logic, is limited to 8-bit width only.[13]

The TX had a 3.5" internal floppy disk drive, with an optional additional internal 5.25" floppy disk drive. It contained ports for two joysticks in the front along with the keyboard, and included a volume control with a 1/8" headphone jack on the front. The back had all of the same ports as the Tandy 1000, except that the light pen port was replaced with an RS-232 serial port. The memory size was 640k (upgradable to 768 kB, with the added 128 kB devoted to video) and the computer came bundled with Personal DeskMate 2.

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

The Tandy SL and TL series of computers were updates of the SX and TX respectively. In addition to offering a redesigned case, the machines offered a much more integrated motherboard with improved graphics and sound capabilities while dropping composite video output. The graphics controller was fully 16-bit wide and 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 onboard 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 an EEPROM memory chip to store BIOS settings (which enabled similar functionality to today's CMOS NVRAMs, so that startup options could be saved). (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, and 6 and Windows 2 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

File:SL Sound Satellite.JPG
The SL's sound/reset satellite board

The Tandy 1000 SL and SL/2 feature an Intel 8086 processor running at 8 MHz, whose slightly higher clock speed and 16-bit bus gave these machines a modest, yet appreciable increase in performance over the 8088-based Tandy 1000 models. The CPU can be replaced with NEC's V30 processor for a further increase in performance. The SL came with 384 kB of RAM preinstalled, whereas the SL/2 offered 512 kB. Both machines can be expanded to 640 kB, although only 608 kB could typically be used by the operating system. The SL line have the mic/earphone ports, volume knob and reset button on a small satellite board, which has an LM386 audio power amplifier, a microphone input IC and a few small passives. There is also a jumper on the board to change the microphone input to a line-level output.[14] The SL series offer five 8-bit XT-compatible ISA slots, and do not come with pre-installed real time clock chips, making them optional upgrades in the form of the plug-in Dallas DS1216E Smartwatch.

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

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

The TL offers five 8-bit XT-compatible ISA slots, while the TL/2 and TL/2 offer 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 offer two upper 3.5" bays and one lower 5.25" bay. The TL/3 also offered a high-density floppy drive controller, though it only shipped with a double density 3.5" drive.

Tandy 1000 RL, RL/HD, RLX, RSX

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, 512 kB of RAM (expandable to 768 kB to provide 128 kB for video and 640kB 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. 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 & Time information with 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.

File:Tandy 1000 rl 1.jpg
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, and unlike other 286-based Tandy 1000s, it supported up to 384 kB of extended memory. However, it was not a full AT-class machine, as it still had an 8-bit ISA bus and only 8 IRQs and 4 DMA channels. While the 3-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. Also, the RLX featured a high-density, 1.44 MB 3.5" disk drive. The RLX offered 512 kB of memory preinstalled, which could be expanded to 1 MB. (The hard disk version came with 1 MB of RAM and a 20mB hard disk preinstalled.)

The RSX offered a 25 MHz 80386SX processor, two 16-bit ISA slots, AcuMos SVGA video, an AT compatible IDE interface and standard PS/2 keyboard and mouse ports. It was a full 386-class PC, and could use up to 9 MB of memory. The RSX still retained the 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 in MS-DOS based software. This works with the game "Chuck Yeager's Air Combat".

Windows 3.xx sound device drivers were available that works 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.

References

  1. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  3. ↑ 3.0 3.1 Lua error in package.lua at line 80: module 'strict' not found.
  4. ↑ 4.0 4.1 4.2 Lua error in package.lua at line 80: module 'strict' not found.
  5. ↑ 5.0 5.1 5.2 Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ 7.0 7.1 Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ 8.0 8.1 Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ 12.0 12.1 Lua error in package.lua at line 80: module 'strict' not found.
  13. ↑ ftp://ftp.oldskool.org/pub/tvdog/tandy1000/documents/txtech.zip
  14. ↑ Lua error in package.lua at line 80: module 'strict' not found.

External links

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