Talk:Mega Man 3 (DOS)

This page of sprite rips links to a file named "PC3Unused.gif" that has the scientist and forklift graphics, plus more: close up of Mega Man and different buster attachments; green shockwave; some kind of ground covering; and a worm creature. They credit the same "S & F Productions" already credited on the wiki page. Mouser (talk) 14:03, 16 May 2018 (EDT)

That worm creature is in the game, but the game won't show the whole thing. BTW the game only stores the forklift graphics in parts. I put them together. I don't know how high the forks should go, so I just guessed something. Frenkel of "S & F Productions" (talk) 18:15, 25 August 2018 (EDT)

Unused code for a 16 color Tandy mode

I saw in the revision history descriptions that Mouser didn't reverse engineer the invincibility cheat in this game. So I did that to see if there are more cheats. There aren't, but I found something else: You can press the f key on the setup menu and the letter "f" will appear next to the "Start Game" menu item. This would disable waiting for vertical retrace in the 16 color Tandy mode. There is some code in the executable for this graphics mode, but choosing Tandy mode just runs the game in 4 color CGA mode. Should this be added on this page? Frenkel (talk) 18:47, 25 August 2018 (EDT)

Yeah! Add it to the page. Nice find. Mouser (talk) 13:49, 4 November 2018 (EST)

I have been working on these two games recently, and I found code for a Tandy mode in the first game, which I have now documented at Mega Man (DOS). However, I did not find any equivalent code in Mega Man 3, only CGA and EGA modes. The 'F' key appears to disable the installation of a timer interrupt (08h), though I haven't determined what the timer interrupt is used for. It doesn't appear to be used to time frames, though? - Rainwarrior (talk) 17:59, 31 July 2019 (EDT)

I looked into the F key and I don't see anything about a timer interrupt. Pressing the F key causes bit 20 to be set at address 593c when the setup menu is closed. The only place in the code I can find that refers to that bit of that address is in a function at 71ec where it controls reading from the VRetrace bit of the Input Status #1 register. (Search for the byte pattern f6063c5920 = test byte [0x593c], 0x20; dx is 0x3d4 after mov dx, word es:[0x63], so dx+6 is 0x3da.) To me, it looks like Frenkel said: the F key is supposed to do something with disabling waiting for vertical retrace. But I did not hit the address 71ec when running the game in the DOSBox debugger. Mouser (talk) 02:23, 23 December 2024 (UTC)

I thought of a different way to search for relevant Tandy mode 9 code and it seems like it does still exist in MM3 as well, with a driver entry point at cs:749Ah. - Rainwarrior (talk) 18:15, 31 July 2019 (EDT)

Just to follow up, the Tandy mode code has not as many functions as the others (16 instead of 19) and for the 16 function pointers it does try to set up, it writes them to the wrong address. The first 16 functions do seem to correlate directly to the first 16 of the CGA/EGA drivers, so I'd presume it was at least partially functional at some point in development but then just abandoned, and later there were more driver functions needed and the table moved. Unfortunately not close enough to a working state for me to want to investigate like I did with the first game, but I guess this means that the developer tried twice to get Tandy 16-color going and failed? Interesting. - Rainwarrior (talk) 18:32, 31 July 2019 (EDT)

Eco Man

Tyler Wilde in PC Gamer, 2017:

Mega Man 3 for DOS ... started as a different game, called Eco Man, which featured a character in a hazmat suit exploring non-linear levels on an oil rig and ship. Hi-Tech Expression said it would publish the game if it were reskinned as a Mega Man game. So that's why, in the video below, you see a bizarre, off-model Mega Man swimming animation.

Lizstar mentions it in her AGDQ 2020 run:

All of the levels in this game are on either oil rigs or in the ocean. This game has an interesting story behind it, and all of it is themed around environmentalism, of all things.

...

To explain, let me go into the deep, varied lore of the Mega Man DOS universe. So this game was made by one dude, his name is Rozner, he is a good dude. It's definitely not easy to make a game by yourself. And for what this is, honestly, I love this game.

...

He made Mega Man 1. He worked at Capcom, and he made it literally as a test to see if he could make DOS games, and turns out, he could. So when he left, independently for other reasons, he messaged back his friends at Capcom, he's like, "Hey I made a Mega Man game, you all want to license it?" And they said, sure. Like I said in my last run, I don't think they looked at it, but they were like, yeah, sure. Capcom allowed that once. That is not the extent of their sins. Then Rozner was working on a personal project using this dude here, this is Eco Man, I believe he is now Radioactive Man. He was making a game where you play as Eco Man, it controls kind of like Mega Man, you choose between some levels, there's a lot of swimming in it, it has an environmental theme. He messaged his friends back at Capcom, and was like, "Hey, I made this game, you all want to license it?" And they go, "Yeah that looks good. Hey are you the guy who made Mega Man DOS? Why don't you just turn him into Mega Man? It's close enough." And he went, "Yeah, sure." So, not only did they allow Mega Man 1 DOS to happen, but they purposefully wanted this. And that is the reason this exists.

Different version for 5¼″ disks? (Or bad archiving?)

The version of the game available from the Internet Archive differs from other versions I've seen. This is immediately apparent at the title screen, where the Internet Archive version doesn't have a "TM" next to the title, and has added text "INSERT DISK 2 FOR 5¼ DISKS" in the corner.

No disk message	"Disk 2" message

There's a similar message about disks in, at least, the Dr. Wily interstitial graphic that is shown after defeating all the Robot Masters.

This would lead me to believe that there were separate 5¼″ and 3½″ floppy disk versions of the game, and that the game files were not identical between the versions. But there are other anomalies that make me wonder if the Internet Archive version is less than pristine, a crack or a modded version perhaps.

First, the executable and game files differ. Another copy of MM.EXE I have found (36114 bytes, sha256sum 50189590a52c90514aca662040bf9e121e1264c78f409eff1e470aba456c7943) is compressed with EXEPACK ("Packed file is corrupt" is visible in the file contents), while the Internet Archive version (114070 bytes, sha256sum ea1f7888f561893a6842b5f70f1fd37138475baacd88c64078411d48929a748c) is not compressed. Some data files seems to have been uncompressed, and their filename extension changed: FSEWER.ZBL (29407 bytes) becomes FSEWER.VBL (36976) in the Internet Archive version. (S&F Productions have documented that: "the data files of Mega Man III are compressed using the LZW compression algorithm.") Even some files that have the same filename are different: BOSS1.VFR is 5777 bytes in the other version, and 4736 bytes in the Internet Archive version.

Second, it seems like there are non-original bugs in the Internet Archive version. The Esc key doesn't work to open the weapons menu (as noted in a review). More significantly, the F5 key functions as an instant-win button: when pressed inside a stage, the game jumps immediately to the weapon get screen for that Robot Master, or, inside the Wily stage, to the victory screen.

So is the "INSERT DISK 2 for 5¼ DISKS" a legitimate version difference, or something added by a modder (as the F5 cheat presumably is)? Could there be other differences?

The transcript of the game manual from The Mechanical Maniacs does mention more than one disk:

1. Turn on your computer system, insert the Mega Man disk into drive A.
2. Type A: and press the Enter key to get to drive A.
3. Type MM and press Enter to start the game.
4. A menu appears with options you can set for optimum game play on your system. Use the Up/Down arrow keys to select an option, and the Left/Right arrow keys to change its setting.
5. Insert Mega Man(TM) disk #2 into drive A when prompted.