Patents are very specific. Without knowing any details of your work or meaning to denegrate it, given how much things have advanced in 3-4 decades, I imagine that the work you did might be considered 'foundations' of what we do today.
Your work should preclude new patents on near-enough the same thing, but does not prevent someone getting a patent on an algorithm which builds upon your work and advances it to a higher level.
(If you had a patent which was still in force, then they may be infringing your patent by building upon it - but that doesn't sound like the case here.)
For more specific feedback here, you'd need to explain (briefly) what you felt was innovative about your work at the time, and which patents you feel are now being applied for (or have been recently filed) that cover essentially the same ground.