How did the Catholic Church function logistically/liturgically prior to the invention of the printing press?

During a *Catholic Mass*, there are a great amount of readings and prayers and scripture extracts/arrangements. There are different reading and set of prayers for almost every day of the year. This applies to both the Novus Ordo and the older, Tridentine Mass, as well as to various liturgies that existed before that too. I've noticed that a lot of parts gets read by the priest from liturgical books (I think the most important one is called a Missal) during the mass. This has got me wondering, how did the church function liturgically for the first 1600 years before the printing press? As I understand it, books were insanely and prohibitively expensive to produce back in the day. I seriously doubt that your average parish in the countryside of the British Isles could afford a handwritten missal. But that leads me to wonder, how did the average parish cope? Readings from the bible and set prayers from the missal are absolutely essential to the liturgy. There is way too much there for a priest to memorise it all, so what did they do if they had to say mass but didn't have access to a bible or missal for the readings and prayers? Or maybe I'm underestimating the Church and in actual fact your average countryside parish *did* have access to all the liturgical books, in which case my question is instead, how did they afford it?