It's pretty interesting to read the red book and try to figure out why things are done the way they are, it really gives some perspective on the progress we've

It's pretty interesting to read the red book and try to figure out why things are done the way they are, it really gives some perspective on the progress we've made in a few decades. An other example of somewhat "obsolete" technology in CDs is that all the track numbers and positions (minute:second:sector) are stored as binary coded decimal which is a bit annoying when you try to manipulate CD data on a modern system. It probably made a lot of sense at the time though, it meant that you could "stream" the BCD data directly to the display without any conversion while binary data would have needed a binary-to-decimal conversion which, I assume, would have been quite costly at the time.