The Atari XE range was the last in Atari's range of 8 bit computers. Essentially they were the same as Atari's other 8-bit offerings, so I'm only talking about the specifics here.

The first to come out was the Atari 130 XE in 1985. This was virtually the same as the Atari 800 XL with a 6502 processor but with 128 K of RAM. The 6502 only had a 16 bit address bus, so the 130 XE had a memory management unit that allowed 4 chunks of 16 K (totalling the extra 64 K) to be bank-switched into main memory. To make things even cleverer, the range had a dedicated display co-processor. This could be told to read from the extended memory, while the main processor read from main memory, allowing you to do quick switching between high resolution graphical screens. Alternatively, SpartaDOS and some other Atari DOS systems allowed you to use the 64 K as a RAMdisk.

After this came the 65 XE. This was a 130 XE with only 64 K of RAM - essentially a reboxed Atari 800 XL.

Finally there was the XEGS - the XE Game System. This was marketted as an expandable game system. You bought the main control unit, which had a cartridge socket and joystick ports and was supplied with a light gun. You could then buy a keyboard at an extra cost, turning it into a normal 65 XE.

There were also rumours of an XEP (Portable) and XEM (high power Music-capable), but they never developed into production.