A selection of some of the major early contributions in chronological order;
first programmer - Ada Lovelace
foundational paper for computerized algebra - Grete Hermann
original programmers of the ENIAC - Betty Jennings, Betty Snyder, Fran Bilas, Kay McNulty, Marlyn Wescoff, and Ruth Lichterman
first compiler written - Grace Hopper
first person to use a computer in a private home & first developer of an operating system (LAP) for the first minicomputer - Mary Allen Wilkes
And all of this was done before Mary Keller became the first American woman to earn a PhD in Computer Science, in 1965, and it wasn't until 1989 that IBM had their first female fellow, Frances E. Allen.
If you are claiming to be finding it hard to find technical contributions to computer science by women and that you see no evidence of discrimination, it means you are being willfully blind, at best.