MerricB said:
With regard to the evolution of the rules of Basic D&D:
<snip... much useful info>
Just to follow up on some of what Merric said. There are some rules differences between the Moldvay and Mentzer Basic sets. We delve into them with glee on Dragonfoot's Classic D&D board. However, these rule differences are so few and far in between, and often times quite subtle, that most won't really notice unless they are paying rapt attention, and even then these rarely effect game play.
The big rule differences come between the Cook (1981 Otus cover) and Mentzer (1983 Elmore cover) Expert boxes. Each of the human classes was toned down in terms of spells received, saving throws, and other abilities. This is due to the fact that with the 1981 set, 14th level was about the end of the road for the characters, while the 1983 set intended for the characters to be able to go up to 36th level.
The Rules Cyclopedia is a compilation of the 4 Mentzer boxes (Basic, Expert, Companion, and Master with the Immortals box being updated in the Wrath of the Immortals box set) plus some additional rules that were added in the Gazetteer series. Overall, the RC is a very nice sourcebook. However, there are some pretty bad errors, especially in the combat section, which sometimes borders on incomprehensibility. There are two unofficial erratas on the Internet:
http://www.dnd.starflung.com/rcerrata.html and
http://www.flxtek.net/~aaron/RCerrata/
The 1991 Black box and the 1994 and 1996 boxes had almost identical content, with some different art and different box sizes. They are very nice rulebooks, with painstaking, step-by-step "how to's" for the youngest players. However, there are some horrible rule problems, the most infamous being the "5' rule".
R.A.