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Tandy 1000 RL

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Tandy 1000 RL
Tandy 1000 RL with CM-11 monitor (Plasticboob)
A Tandy 1000 RL with a CM-11 monitor (photo: Plasticboob, CC BY-SA 3.0)
Specifications
ManufacturerTandy Corporation, sold by Radio Shack
TypeCompact desktop personal computer (IBM PC compatible)
CPUIntel 8086, 9.54 MHz, surface mounted
Memory512 KB, expandable to 768 KB
StorageOne 3.5-inch 720 KB floppy drive; bay for a second 720 KB drive or a 20 MB SmartDrive
DisplayBuilt-in Tandy video: MDA, Hercules, CGA and Tandy enhanced modes
SoundThree-voice sound and an 8-bit DAC with microphone input
PowerInternal fanless supply, 25 W
OS / FirmwareMS-DOS 3.3 and DeskMate in ROM
Model no.25-1450

The Tandy 1000 RL is a compact, fanless IBM PC compatible in the Tandy 1000 family, sold by Radio Shack from 1991 as a home computer. It has a 9.54 MHz 8086, the video and sound of the Tandy 1000 SL, MS-DOS and the DeskMate interface in ROM, one expansion slot and a built-in interface for Tandy's XT IDE "SmartDrive" hard disks.[1][2] The Tandy 1000 RL-HD is the same machine with a 20 MB SmartDrive and a clock fitted.[3]

History

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Radio Shack's 1991 catalogue sold the RL for $599.95 (catalogue number 25-1450) as a "home information center", bundled with DeskMate and the Home Organizer software. It stressed the small case, 2 7/8 x 15 x 14 inches, and that the RL needs no cooling fan.[3] The 1992 catalogue cut the price to $499.95 and added the Tandy 1000 RLX.[4]

Specifications

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Tandy 1000 RL (Radio Shack catalogues, 1991-1992)
Item Specification
Processor Intel 8086, 9.54 MHz
Memory 512 KB, 768 KB maximum
Real-time clock Optional
Video MDA, Hercules, CGA and Tandy's extra graphics modes
Floppy drive One 3.5-inch 720 KB; room for a second 3.5-inch 720 KB drive
Hard disk 20 MB or 40 MB SmartDrive optional
Expansion One 10-inch slot
Ports RS-232C serial, parallel, PS/2-style mouse, two joysticks, microphone, headphone
Keyboard 101-key
Software in ROM MS-DOS 3.3, DeskMate interface, spelling checker
Power supply 25 W
Size 2 7/8 x 15 x 14 in (H x W x D)

Sources: Radio Shack catalogues RSC-22, RSC-22A and RSC-23.[3][1][4]

Hardware

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Processor and memory

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The 8086 is surface mounted and cannot be replaced, and there is no maths coprocessor socket.[5] Memory goes from 512 KB to 768 KB with two 256K x 4 DRAMs of 100 ns in sockets U19 and U23; there is no jumper. As on other Tandy 1000s with Tandy video, the video circuit takes part of the memory.[6] Tandy's 1995 parts list gives the processor as an 8086-1 at U17 and shows a 40-pin socket for the BIOS ROM at U30 and an 8-pin socket for the serial EEPROM at U18.[7]

Storage

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The built-in hard disk interface takes XT IDE drives only, not ordinary AT IDE drives.[8][2] The FAQ says that only Western Digital MFM or RLL controllers work in the RL, that Tandy's 25-1095 AT IDE hardcard fits once its bracket is trimmed, and that a 40 MB drive in the RL may show only 20 MB.[8] The 3.5-inch drives take their power through the data cable.[9]

Ports and keyboard

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The RL has a 25-pin parallel port in place of the card-edge port of earlier models. The FAQ and Wikipedia describe it as unidirectional, although Radio Shack's 1991 comparison table ticks "bidirectional parallel port" for the RL.[10][2][1] The keyboard and mouse connectors look like PS/2 ports, but the keyboard uses the XT protocol, so a modern PS/2 keyboard works only if it can switch to XT.[11][12] The mouse port needs a special driver because it does not use the usual IRQ 12; one owner recalls that it uses IRQ 3. CuteMouse works with it, and the port may need enabling in the setup program.[12][13]

Power supply

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The supply is rated at 25 W and has no fan.[1][3] The RL, RLX and RLX/HD parts lists give the same power conversion parts, including converter transformer TB0337 (T1), a 150 µF 200 V capacitor (C7), switching transistor MJF13007 (Q1) and a 1 A 125 V fuse (F1).[7][14] An owner fitted an RL supply to a Tandy 1000 RSX and reports that it is a drop-in replacement.[15] See Tandy 1000 RL Capacitor Replacement Guide.

Known faults

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  • Shorted tantalum capacitors on the main board. One RL gave a wailing tone and smoke at switch-on; the cause was a burnt surface-mount tantalum, C98.[16]
  • Cracked supply boards. One owner's supply board cracked when someone pressed the power switch too hard.[17]
  • A corrupted EEPROM, or a wrong setting such as a disabled floppy controller, can leave the machine unable to boot.[18][19]
  • The FAQ lists BIOS 02.00.01 as the RL's last version, correcting lock-ups in DeskMate caused by a mouse driver bug.[20]

See Tandy 1000 RL Troubleshooting Guide.

Documentation

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Tandy's parts list names a service manual (25-1450) and a user's manual for the RL; neither could be obtained.[7]

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References

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  1. ↑ 1.0 1.1 1.2 1.3 Radio Shack, computer catalogue RSC-22A (1991), p. 7, "Home office and family PCs", page scan at RadioShackCatalogs.com (retrieved 2026-10-22).
  2. ↑ 2.0 2.1 2.2 "Tandy 1000", Wikipedia (retrieved 2026-10-21). Sections "Tandy 1000 RL-series and RSX" and "1000 RL and RL/HD".
  3. ↑ 3.0 3.1 3.2 3.3 Radio Shack, computer catalogue RSC-22 (1991), p. 15, "The Tandy 1000 RL is your home organizer", page scan at RadioShackCatalogs.com (retrieved 2026-10-22).
  4. ↑ 4.0 4.1 Radio Shack, computer catalogue RSC-23 (1992), p. 8, "Home office and family PCs", page scan at RadioShackCatalogs.com (retrieved 2026-10-22).
  5. ↑ Jeff Hayes, "Tandy 1000-series FAQ", version 2.52, 25 October 2005, TVDog's Tandy 1000 archive (retrieved 2026-10-21). Sections II.F.1 and II.F.2.
  6. ↑ Hayes, "Tandy 1000-series FAQ" (2005), sections II.A.1 and II.A.3.
  7. ↑ 7.0 7.1 7.2 Tandy National Parts, bill of materials 250-1450 "Tandy 1000 R L", January 1995, 25-1450.txt, TVDog's Tandy 1000 archive (retrieved 2026-10-21).
  8. ↑ 8.0 8.1 Hayes, "Tandy 1000-series FAQ" (2005), section II.D.1.
  9. ↑ Hayes, "Tandy 1000-series FAQ" (2005), sections II.C.2 and II.C.5.
  10. ↑ Hayes, "Tandy 1000-series FAQ" (2005), section II.H.2.
  11. ↑ Hayes, "Tandy 1000-series FAQ" (2005), section II.E.1.
  12. ↑ 12.0 12.1 "Tandy T-1000 RL/HD", Vintage Computer Federation forum, January 2012, thread. Posts by vwestlife and Great Hierophant, 31 January 2012.
  13. ↑ Hayes, "Tandy 1000-series FAQ" (2005), section II.G.5.
  14. ↑ Tandy National Parts, bills of materials 250-1452 "Tandy 1000 RL-286" and 250-1453 "Tandy 1000 RL/286 HD", January 1995, 25-1452.txt and 25-1453.txt, TVDog's Tandy 1000 archive (retrieved 2026-10-21).
  15. ↑ "Tandy 1000 RSX PSU replacement", Vintage Computer Federation forum, May-June 2025, thread. Posts by jasa1063, 30 May and 4 June 2025.
  16. ↑ "Tandy 1000 RL tone of death", Vintage Computer Federation forum, February 2021, thread. Posts by falter, daver2, keenerb and compaqportableplus, 14-20 February 2021.
  17. ↑ "Building a Tandy 1000 RL\RLX power supply", Vintage Computer Federation forum, May-August 2012, thread. Posts by Compgeke (15 May 2012) and Great Hierophant (28 August 2012).
  18. ↑ Hayes, "Tandy 1000-series FAQ" (2005), sections II.K.8 and III.F.2.
  19. ↑ "Help with Tandy 1000 RL/HD", Vintage Computer Federation forum, March 2023 to March 2024, thread. Posts by Scottmm78, SteveHere, indyjoenz, dr.zeissler and Cloudschatze.
  20. ↑ Hayes, "Tandy 1000-series FAQ" (2005), section III.E.2, BIOS version table.


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