I don't know what the modules Bowman is unplugging in the HAL computer represented in the film back then, but today they can easily be seen as each being a CPU

I don't know what the modules Bowman is unplugging in the HAL computer represented in the film back then, but today they can easily be seen as each being a CPU board, GPU or SSD. Maybe in the 60s they represented circuits with a few transistors, magnetic cores or tapes. It's interesting that the art style was made universal enough to work for computing technology of any era