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 uses 8 MHz Intel 80286 processors, whereas the TL/3 uses a 10 MHz 80286. The TLs has 640 KB of memory preinstalled, with an option for an extra 128 KB for video frame buffering just as in the 1000 TX. Unlike the SL series machines, the TL series comes 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/3 offer four slots and an on-board 8-bit, XT IDE-compatible hard disk interface, which is not compatible with standard AT IDE hard drives. The TL series offers two upper 3.5" bays and one lower 5.25" bay, and has a high-density floppy drive controller for 1.44 MB drives, though it comes with a double-density 3.5" 720 KB drive. As the processors on the TL-series are socketed, it is possible to install 386SX or Cyrix 486SLC-based processor upgrades, though the benefit of installing more advanced processors is limited beyond merely providing a speed increase due to the computers' XT-based architecture, and their resulting inability to access extended memory above 1 MB. Tandy 1000 RL-series and RSX The Tandy 1000 RL/RLX/RSX are slim-line desktop home computers. They have a much more compact case, with at least 512 KB of memory pre-installed, smaller PS/2-style keyboard and mouse ports, and at least one ISA expansion slot. The RL-series and RSX include provisions for an internal hard disk drive, depending on the model: the RL-series features a built-in XT-IDE hard drive interface, while the RSX features an AT-compatible IDE interface. The keyboard connectors of the RL-series, while similar to and mechanically compatible with PS/2-style connectors, are not fully compatible with typical PS/2 keyboards, as the keyboard uses the XT keyboard protocol. The RSX, however, incorporates the AT keyboard protocol, making it the first 1000-series system to offer more complete compatibility with typical PS/2 keyboards, and AT keyboards using an adapter. 1000 RL and RL/HD The RL and RL/HD features a surface-mounted 8086 processor, 512 KB of RAM (expandable to 768 KB to provide 128 KB for video and 640 KB conventional memory), a DB-25