How does buddhism describe what exactly, or where exactly, or how exactly, consciousness exists?
As a computer scientist you are bringing some baggage with you that will continue to get in the way of what you want to find in the Dharma. I am speaking from the perspective of a computer scientist that spent thirty years looking into the same questions you are asking, ultimately finding the answers  in contemplative practice.
While consciousness is categorized in the Dharma in ways that may have led you to believe that consciousness is some thing that exists separate and apart from its cognitive contents, reaching out to contact that content, the actual structure, which you can discover first-hand through meditative practices (today’s mindfulness meditation being the first baby-step on the path) is the inverse of what you believe it to be.
For me, the ultimate roadblock on the path you are following was explaining human creativity (rather than explaining it away), because, upon analysis, the proposed solutions to explaining it always assumed the result, and thus were never more than magical thinking. An example is the foundational belief, found widespread in many fields of knowledge, that order arises randomly—and sticks around—without some organizing principle driving it. That’s magical thinking.
Consciousness of some object being taken as a structure of real things harboring a ghost in the machine that somehow imparts a new feature onto its dull matter, no matter how subtly the mechanism is crafted, must assume as a given, the ability to know, be aware, or be cognizant of those skandas you’ve read about. It’s not to be found in dull matter, so you have to turn the problem around.
If you want a textual reference to an in-depth treatment of mind, and specifically “where is mind?” I highly recommend the Surangama Sutra, also known as The Sutra of Heroic Progress. There are three extant English translations of it, with my favorite being the Goddard translation because of it’s conciseness (repeating material being skipped), and the lengths gone to by the translators and the editor, Goddard, to not use unfamiliar terminology.