Neo-Geo.com has posted a digitized development manual from SNK’s old system and Gamasutra have posted an article that highlights some of the more interesting portions of it. Here’s a section on development guidelines:
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Another section outlines the flow of a game after you boot it up. Yet another after that provides instructions for how to handle situations related to Continue screens:
The full development manual is over 200 pages in length, covering everything from guidelines to technical specifications. You can find it via the articles linked to above.