Complex sentence: Data General and Texas Instruments' small computers were not very successful, but observers expected AT&T to soon enter the computer industry, and other large companies such as Exxon, Montgomery Ward, Pentel and Sony were designing their own microcomputers.
Split into simpler sentences: Data General and Texas Instruments' small computers were not very successful. Observers expected AT&T to soon enter the computer industry, and other large companies such as Exxon, Montgomery Ward, Pentel and Sony were designing their own microcomputers.