I don't think you can generalise answers here.
My wife worked in IT for 20 years, and for most of that time she had female managers. Much of this time was for Universities and other parts of tertiary education, in the IT depts that provide services like payroll, records, and so on.
The tertiary education sector IT services groups tended during that period to have roughly equal split (about 50:50, but it varied, maybe 60:40 in some places) males:females.
Promotion was a hit and miss affair. Sometimes people were promoted from within, frequently senior management appointments were made from external applicants. A great many of the successful external applicants were women, my recollection is that over 50% of the managers during that period were female, and a majority of them were external appointments.
There have been other comments here about IT tending to be a meritocracy: it certainly seemed to be that way in this case. Mind you, it is also the law that this be the case.
UPDATE TO ANSWER A QUESTION: Most of this was development roles, eg writing and modifying systems software, later on acceptance testing of a large software supply contact, and later again as a DBA.
[The experience of women working for female managers is a the subject of a completely separate discussion.]