The fourth-generation computers became available in the 1980s when very large-scale integration (VLSI), in which thousands of transistors and other circuit elements are placed on a single chip, became increasingly common. The VLSI technology greatly increased the circuit density.
While the first-, second-, third-generation computers used ferrite core as memory units, the fourth-generation computers used semiconductor devices fabricated by VLSI technology as ultrahigh-access memory units. The drop in cost associated with the size-reduction trend led to the introduction of personal computers for use in office, schools, homes etc., so NCR began to produce and market personal computers with enormous success.
At the related pages I'll try to present the most significant of them.
May 27, 1987. NCR Announces 80386-Based PC.
May 27, 1987. NCR Introduces Advanced Functionally Modular AT-Compatible PC.
May 27, 1987. NCR Introduces PC Communications Product Set.
May 27, 1987. NCR Introduces Modular Communications Workstation.
May 27, 1987. NCR Introduces PC Product Family Based on "Incremental Workstation Architecture".
May 27, 1987. NCR Introduces New Modular PC Architecture.
Mar 11, 1993. NCR System 3000: The Champion of Intel/Unix Multiuser Systems. Aberdeen Group.