The best uses for out of date opening books are -
Emergency toilet paper supply when Covid means the supermarket has sold out
how far in terms of opening knowledge and building my opening
repertoire will memorising every line of the book get me?
You will be an expert in historical opening lines, but you will understand nothing.
This depends quite a bit on your level of understanding, as well as your knowledge of relevant programming languages.
David Levy wrote a number of books that deal fairly closely with this topic. "Chess and Computers" (1976) is more for the beginner, while his "Computer Chess Compendium" is more 'medium' and above. See his biography/...
FM Bill Jordan has written several, including:
How to Write a Chess Engine
The Joy of Chess Programming: How Chess Engines Work
How to Write a Bitboard Chess Engine: How Chess Engines Work
The first is basically a printout of his engine's code, with an explanation of each code segment.
You aren't going to learn much that you couldn't learn from a database. MCO has very little explanation.
I will say though that it is useful to quickly run through an opening and get a feel for the types of typical positions that come up. Also, sometimes the positional evaluations might be interesting especially if they contradict the engines and databases.
This book is a reference manual. Each page shows a diagram position from 2 to 10 moves deep. Beneath the diagram columns of chess notation denote how different games have proceeded from that position. The next page will usually contain the many footnotes referenced from the columns. These include source games or mentions of interesting alternatives.
Is it ...
MCO is an excellent source of information. In fact, opening encyclopedias actuality are not related to the existence of chess engines or to the latest that has been played. Rather, the variants selected by the encyclopedia are important because the players who selected them are people with extensive experience in the field.
The time that has elapsed since ...
I use a modified version of De La Maza's approach.
The first time just go through it normally. Keep track of the amount of time you spend and which ones you get wrong. Play through the ones you get wrong until you understand them.
The second time through do the same thing except cut the amount of time in half. If for some reason you can't cut the time in ...