TTL would legally rename itself Atari Corp and would pursue development of its key product line, codenamed "RBP" which stood for Rock Bottom Price.   This would eventually be named the "ST" computer line, ST standing for Sixteen-Thirty bit computers.

Another group within the new Atari was called the "Legacy group" - these would be a team of engineers, many carry-overs who were hired from the old Atari Inc over to Atari Corp to pursue the use of existing Atari XL designs and implement new product designs based on them.

From July through August of 1984, Atari Corp initially intended to implement a rather bold effort to develop and release several new computer designs.   Including LCD based systems, wordprocessor systems, AMY based music systems and all of these computers would have built in 3.5" disk drive controllers.

August 13, 1984 Engineering Memo

However, by early September 1984, the product line would be drastically altered down to a strategy of using Atari Inc's earlier Atari 800XL and 800XLF designs and creating a path to releasing different versions that would cost reduce the 800XL based system down through 4 different variations.

XL Product Line September 9, 1984 Memo

By October of 1984, due to very difficult financial issues facing Atari Corp, to at one point Jack Tramiel had to go back to Warner Communications and renegotiate the sale terms and receive a loan to continue operations of Atari Corp.   The XL line would be further reduced down to just the release of only the 800XLF, initially a SECAM version and then later a limited run of NTSC/PAL version.   The first of the cost reduced 800XLF versions - the 900XLF would be renamed to the 65XE and would be released in the beginning of 1985.    A 128K version of the 900XLF would be released in April of 1985 called the 130XE.

In 1987 Atari would introduce an XE system called the XEGS and finally in 1988 the last version of the XE line would be released called the 800XE.  In 1992 all production and sales of XE computers would be discontinued.