The complete official SNES Development Manual, from Nintendo of America, is up on archive.org. This document contains a wealth of technical information on the system, its peripherals, and extra chips like the DSP-1, the Super FX and the SA-1.
The book also contains interesting information on the licensing and approval process! Some things specifically listed as potential issues for approval (page 1-2-4 to 1-2-5) are the player being able to get somewhere without hope of escape, the inability to pause somewhere during gameplay, “inconsistent scoring methods,” calling the controller or cartridge by unacceptable terms like “joystick” or “cassette,” accidentally leaving Super Famicom-style colored buttons in depictions of the controller, and whether there are vowels in the password system.
