Tandy 1000 - Selected Tandy 1000 Models - Tandy 1000 SX/TX

Tandy 1000 SX/TX

The Tandy 1000 TX was very similar to the Tandy 1000, having an external keyboard and similar casing. The most major difference was the use of an 80286 CPU; otherwise, it was nearly identical to the Tandy 1000, including the unique parallel port edge connector. Despite the 80286 processor, it was still an XT-class PC, not an AT-class PC, as it adapted the 80286 to operate over the same 8-bit data bus as previous Tandy 1000 models, and had 8-bit XT-style expansion slots. As such, it could not operate in 80286 protected mode or perform 16-bit memory or I/O transfers in one bus cycle, but it did benefit from the higher speed of the 80286 and its other added instructions in real mode. 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 DeskMate.

The Tandy 1000 SX was the lower-end sibling of the TX, and was essentially an upgraded reissue of the original Tandy 1000. 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, and lacked the volume control and headphone jack of the TX (also like the original 1000). The Tandy AX was a Tandy SX rebadged for sale in Wal-mart stores.

The 1000 SX came with MS-DOS 3.2 and Deskmate 2 on 5.25" 360 kB diskettes. 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.

All original Tandy-provided internal floppy disk drives for the 1000 SX and TX were double-density drives. The Tandy 1000 SX and TX were the first models in the Tandy 1000 line to have a built-in DMA controller. The earlier 1000/1000A, 1000 HD, 1000 EX and 1000 HX models, like the IBM PCjr, did not have a DMA controller, but could be upgraded with one. The DMA controller chip was included on the PLUS-type memory expansion board for the EX and HX, and on regular ISA memory expansion cards sold by Tandy and other companies for the 1000, 1000A, and 1000HD. Adding the DMA chip improved the speed and IBM PC-compatibility of these earlier Tandy 1000 models.