If you want to get the full dose of what Gygax wrote for the 1st edition of Advanced Dungeons & Dragons look at A.D.D.I.C.T. It explains the AD&D combat system in full. It is 20 pages, the first 10 pages goes rule by rule through the entire system and the rest is a detailed combat example. David M. Prata put this together and went the extra mile by footnoting everything so you can go back to the rulebook and see if he got it right in your opinion.
While you are at Dragonsfoot you may want to browse around. They have many excellent downloads for older editions of D&D.
5th Edition Keep on the Borderlands, Part II
3 hours ago