AT&T Computer Systems yesterday launched a notebook computer that comes in two models with preloaded and pretested software that includes MS-DOS 4.01, Windows 3.0, an advance release of AT&T Access Plus for Windows, and a custom tutorial. The base model weighs 7 lbs 5 oz with two batteries that provide up to six hours of portable computing life. Available now, the Safari NSX/20 notebook computer costs $5,400 with 40Mb hard disk, 2Mb to 6Mb, 3.5 floppy, built-in 2,400bps modem, mouse, an AC power adaptor and charger. An 80Mb hard disk version will be available in the third quarter with 4Mb RAM expandable to 8Mb, and 2,400/9,600bps data-facsimile modem, which is upgradeable to meet evolving wireless communications standards. It is the same weight and will be $6,400. The notebooks come from the Safari Systems joint venture between AT&T and Marubeni America Corp and is US-made by Panasonic Industrial Co.