The Missile Command ROM set has 7 files in it, but it's a lot easier to disassemble if you have all of the program ROM in one. The MAME data file specifies their locations like this:
| Filename | Size | Region | Offset |
|---|---|---|---|
| 035820-02.h1 | 2048 | maincpu | 5000 |
| 035821-02.jk1 | 2048 | maincpu | 5800 |
| 035822-03e.kl1 | 2048 | maincpu | 6000 |
| 035823-02.ln1 | 2048 | maincpu | 6800 |
| 035824-02.np1 | 2048 | maincpu | 7000 |
| 035825-02.r1 | 2048 | maincpu | 7800 |
| 035826-01.l6 | 32 | proms | 0 |
We're only interested in the "maincpu" items.
Launch SourceGen, select Tools > Concatenate Files. Navigate to the Missile Command ROM directory, and add the first six items listed above (just select all the files that appear to be 2K in size). Use the Up / Down buttons to arrange them in the order shown above. Click Save and save it as "MissileCommand". It should look something like this:
Copyright 2021 by Andy McFadden