The ABA notes this progression of its adopted ethical rules:*
1908 Canons of Professional Ethics (last amended 1963)
The 1908 Canon notes that it was modeled on the 1887 code adopted by the state of Alabama that eleven other states had, at the time, also adopted in some form
Model Code of Professional Responsibility (1969)
Included nine Canons, further explained by Ethical Considerations (EC) and Disciplinary Rules (DR)
ABA Model Rules of Professional Conduct (1983)
Includes the rules and comments to the rules, designed to help explain their meaning and purpose
* Remember that an ABA adoption alone does not mean it has the force of law in a particular state; that generally requires the state to affirmatively adopt the rules.
A Legislative History: The Development of the ABA Model Rules of Professional Conduct, 1982-2013 by 
A Legislative History: The Development of the ABA Model Rules of Professional Conduct, 1982-2005 by 
The Legislative History of the Model Rules of Professional Conduct: Their Development in the ABA House of Delegates by