This slideshow (PPTX format) with plenty of slide notes describes how to reason your way through editing the tiles and tile map of Midway MCR-III games (1983-85). The examples shown in the presentation highlight nuances of the Tapper ROMs.

You will learn what tools are necessary to not just edit the ROMs, but also produce clean graphics that match the game’s palette. In addition to editing the graphics ROMs, a technique is also described that will help you avoid ROM errors resulting from incorrect checksums when you edit the tile map.

This guide is generic enough to help you understand graphics hacking in general for tile-based systems, but should be directly applicable to the following MCR-3 games:

Demolition Derby

Discs Of Tron

Root Beer Tapper

Sarge Cocktail

Tapper

Timber

Stay tuned for the associated utility to be posted here once I clean it up a bit and make it more user-friendly.

In case you can’t view PPTX files or want to see it on the go, this document can also be viewed online at: http://www.slideshare.net/StephenWylie3/process-of-arcade-rom-hacking