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Tandy 1000 HD

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Tandy 1000 HD
Tandy 1000 with VM-2 monitor (Jud McCranie)
An original Tandy 1000. The 1000 HD uses the same chassis and case top (Tandy parts 8729314 and 8719438) with a hard disk fitted. No freely licensed photograph of a 1000 HD was found (photo: Jud McCranie, CC BY-SA 4.0).
Specifications
ManufacturerTandy Corporation, sold by Radio Shack
TypeDesktop personal computer (IBM PC compatible)
CPUIntel 8088, 4.77 MHz
Memory256 KB
Storage10 MB Tandon TM252 hard disk; one 5.25-inch 360 KB floppy drive
DisplayPCjr-compatible video; RGB and composite outputs
SoundTexas Instruments SN76496, three voices
PowerInternal 54 W switching supply
OS / FirmwareMS-DOS 2.11 and DeskMate
PredecessorTandy 1000
Model no.25-1001, 25-1001A

The Tandy 1000 HD is the hard disk version of the Tandy 1000, catalogue number 25-1001. It has a 10 MB Tandon TM252 hard disk and a Western Digital WD1002S-WX2 controller fitted at the factory.[1] Tandy fitted two main boards: a version of the original 1000 board (PCB 8709556A), and the cost-reduced board of the Tandy 1000A.[2]

History

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TVDog's model list gives 256 KB as standard memory for the 1000 HD, against 128 KB on the 1000 and 1000A, with production around 1986.[3] An owner writing in the late 1980s describes buying a "1000A HD (cat. #25-1001A)" in December 1985 with a Tandon TM-252 drive.[4] Wikipedia describes the HD as a 1000A with a factory hard disk of 10 or 20 MB; Tandy's own supplement covers only the 10 MB drive and both board versions.[5][2]

Specifications

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Tandy 1000 HD (25-1001)
Item Detail
CPU Intel 8088, 4.77 MHz
RAM 256 KB standard
Hard disk Tandon TM252: two 130 mm platters, 306 cylinders, 3600 rpm, 12.76 MB unformatted, 10 MB formatted
Hard disk controller Western Digital WD1002S-WX2, set by jumper block SW1 for a 306-cylinder, four-head drive
Floppy drive One 5.25-inch 360 KB drive
Main board "Tandy 1001" main logic, PCB 8709556A, or the 1000A board
Power supply 54 W board, Tandy part 8489073 in the main assembly list

Sources: Tandy's supplement and the TM252 manual reprinted in it, the TVDog model list, and a 1997 note on adding a second drive.[1][6][3][7]

Hardware

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The case, chassis, fan, speaker and front reset buttons carry the same Tandy part numbers as the original 1000's.[8][9] The early HD main board uses the same capacitor positions as the 1000's, with a few differences in the ratings listed and a 0.25 A Pico fuse (F1) on the board.[10] Disassembly, the main board and the 54 W supply are covered on the Tandy 1000 pages.

The Tandon drive draws 2.0 A typical and 2.4 A maximum from +12 V for up to 12 seconds at start-up, and 1.4 A typical (1.8 A maximum) while running, plus 0.5-0.8 A from +5 V.[6] That is more than the 1.25 A that Tandy specifies for the +12 V output of the original 1000's 8790070 supply.[11] The HD's assembly list names a different supply part number, 8489073, and the supplement gives no ratings or parts list for it.[8] An owner reports that Tandy customer service told him the HD supply could run two 17 W hard drives.[4]

Known faults

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  • Tandon gave the TM252 a component design life of five years and a mean time between failures of 11,000 power-on hours. It needs no preventive maintenance, but its heads are parked at cylinder 305 for shipping, and Tandon advises parking them before power-down.[12] See Tandy 1000 HD Troubleshooting Guide.
  • One owner replaced a failed MFM drive with an XT-IDE adapter and a CompactFlash card, and a failed 360 KB floppy drive with a 1.44 MB drive set up as a 720 KB unit.[13]
  • Power supply and main board faults are the same as on the original 1000; see Tandy 1000 Troubleshooting Guide.

Documentation

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References

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  1. ↑ 1.0 1.1 Radio Shack, Tandy 1000 HD Service Manual, catalogue no. 25-1001, supplement to the Tandy 1000 Service Manual (25-1000), Tandy Corporation, 1986, hosted as File:Tandy 1000 HD Service Manual (25-1001, 1986).pdf. Contents; Introduction, p. 1; parts lists pp. 23-33; component information (TM252, WD1002S-WX2).
  2. ↑ 2.0 2.1 Tandy 1000 HD Service Manual (25-1001), Introduction, p. 1.
  3. ↑ 3.0 3.1 Jeff Hayes, "models.txt", TVDog's Tandy 1000 archive, 2005 (retrieved 2026-10-21). Short list of 1000-series models: processor, standard memory, catalogue number and approximate production date.
  4. ↑ 4.0 4.1 "A Second Hard Drive for the Tandy 1000HD", dcshd.txt, TVDog's Tandy 1000 archive (retrieved 2026-10-21). Author not recorded in the file.
  5. ↑ "Tandy 1000", Wikipedia (retrieved 2026-10-21). Section "Tandy 1000 HD".
  6. ↑ 6.0 6.1 Tandon Corporation, TM252 Rigid Disk Drive product specification, document 179050-001 Rev. B, Table 2.1 "Electrical and Operational Specifications", pp. 2-1 to 2-2, reprinted in the Tandy 1000 HD Service Manual (25-1001), component information section.
  7. ↑ "Adding a second (external) hard drive to the Tandy 1000HD", t1khd.txt, TVDog's Tandy 1000 archive (retrieved 2026-10-21). WD1002S-WX2 controller, SW1 jumper positions, drive types.
  8. ↑ 8.0 8.1 Tandy 1000 HD Service Manual (25-1001), "Tandy 1001 Main Logic Main Assembly", p. 31.
  9. ↑ Radio Shack, Service Manual: Tandy 1000 Computer, catalogue no. 25-1000, 1985, hosted as File:Tandy 1000 Service Manual (25-1000, 1985).pdf. Main Logic parts list, p. 99.
  10. ↑ Tandy 1000 HD Service Manual (25-1001), "Tandy 1001 Main Logic Sub Assembly", pp. 32-33.
  11. ↑ Tandy 1000 Service Manual (25-1000), "Power Supply Operating Characteristics", p. 79.
  12. ↑ Tandon, TM252 specification (179050-001 Rev. B), Table 2.1 continued (park note, MTBF, design life, preventive maintenance) and p. 2-6, reprinted in the Tandy 1000 HD Service Manual.
  13. ↑ "Tandy 1000 model 25-1002", Vintage Computer Federation forum, January 2024, thread. Post by seaken, 8 January 2024 (1000HD with 360 KB floppy and MFM hard drive; XT-IDE and CF card fitted).


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