[Sik]

Holy crap on the Sega CD RAM amount. You're getting it all wrong.

The Sega CD adds two pieces of RAM: 256KB for exclusive use by the sub-CPU (though part of it is eaten by the BIOS) and 512KB for use between the sub-CPU and the main-CPU. The former is called PRG-RAM, the latter is called Work RAM.

Moreover, the latter can either be given exclusively to one CPU, or split in half and give each part to each CPU. Considering how a Sonic game would use it, I'd say that giving all the RAM to one CPU would make the most sense (the other mode is mainly meant for FMV, acting mainly as a double buffer - in fact things like rotation, scaling and such can't be done in that mode).

Shadow Hog, on 07 December 2011 - 10:38 AM, said:

Sik, on 07 December 2011 - 03:19 AM, said:

Not to mention the Z80 can't access MCD hardware, so for games that use SMPS/Z80 you will have to replace the sound engine.

Ah, so is that why Sonic CD has its unusual jumping noise? I had been wondering.

Doesn't really explain why Chaotix also went with it, since I'm pretty sure I heard Z80 use in the music (the Z80's where the square wave/noise channels come from, correct?), but eh.

They just went with that because they had the FM channels free now, nothing else really. And as has been said, the Z80 doesn't output any sound, it's just another processor.

[Iron Sonic]

Sik, on 08 December 2011 - 03:56 PM, said:

Holy crap on the Sega CD RAM amount. You're getting it all wrong.

The Sega CD adds two pieces of RAM: 256KB for exclusive use by the sub-CPU (though part of it is eaten by the BIOS) and 512KB for use between the sub-CPU and the main-CPU. The former is called PRG-RAM, the latter is called Work RAM.

Moreover, the latter can either be given exclusively to one CPU, or split in half and give each part to each CPU. Considering how a Sonic game would use it, I'd say that giving all the RAM to one CPU would make the most sense (the other mode is mainly meant for FMV, acting mainly as a double buffer - in fact things like rotation, scaling and such can't be done in that mode).

My colleague misspoke when explaining the 256KB limit. Indeed, the PRG-RAM is separate from the Word RAM. However, the Word RAM size is 256KB in size, usable as a single chunk in 2M mode or as two interchangeable 128KB chunks in 1M mode. Please do refer to these three pages of the scans for the Rex Sabio scans of the official Mega-CD Hardware Manual (dated 1991/10/14):

http://dl.dropbox.co...0926/Cdh-12.gif
http://dl.dropbox.co...0926/Cdh-13.gif
http://dl.dropbox.co...0926/Cdh-14.gif

Definitely not the most well-done scans ever made, but should be readable enough to clarify this minor question over the 256KB limit.

This post has been edited by Iron Sonic: 12 December 2011 - 01:44 PM

[ZeroShift]

It appears the site went down during the CD download.

Anyone have any mirrors? Or do you know when the site will be back?

[Chibisteven]

ZeroShift, on 09 December 2011 - 06:15 PM, said:

It appears the site went down during the CD download.

Anyone have any mirrors? Or do you know when the site will be back?

I don't have the example disk. But I've included a cue sheet for beginners and a note on how to edit it with Windows Notepad.

http://www.mediafire...c7ym8vct98ifzfg

EDIT: I failed to mention that this is the second revision of the ROM hack by theocas, sorry about the confusion.

This post has been edited by Chibisteven: 09 December 2011 - 10:35 PM

[Iron Sonic]

I'll work on getting a mirror up within the next few hours. As noted many times before, however, you can make your own soundtracks for the game without much difficulty. The track listing is on the OP.

EDIT: Here's the backup links:

ROM: http://dl.dropbox.co...Sonic1Mode1.bin
CUE: http://dl.dropbox.co.../Audio%20CD.cue
BIN: http://dl.dropbox.co.../Audio%20CD.bin

This post has been edited by Iron Sonic: 09 December 2011 - 11:27 PM

[ZeroShift]

Sadly at the moment I need the ROM. I got a custom track set, so I'm set for that.

[Chibisteven]

ZeroShift, on 09 December 2011 - 09:08 PM, said:

Sadly at the moment I need the ROM. I got a custom track set, so I'm set for that.

Look at my post above. It has the ROM. The file is the second original revision of the ROM hack by theocas. The zip is called Sonic1Mode1update.zip. Sorry I didn't make it clear enough in the original post. It was a major screw up on my part.

This post has been edited by Chibisteven: 09 December 2011 - 10:34 PM

[theocas]

Sorry about the screwup with the server on my part - it should be all fixed. I had some issues with software on my server, as well as with my server provider's internet backbone. Apparently a network switch failed.

[ZeroShift]

Chibisteven, on 09 December 2011 - 10:33 PM, said:

Look at my post above. It has the ROM. The file is the second original revision of the ROM hack by theocas. The zip is called Sonic1Mode1update.zip. Sorry I didn't make it clear enough in the original post. It was a major screw up on my part.

Don't sweat it, I didn't even bother opening the link to see it was what I needed.

Thanks guys for making this awesome hack! I was waiting on SonMP3 to be properly set for more than just S1SAGE2010.

[Shade Vortex]

I would love it if this were done for the other classic Sonic games, especially Sonic 2 since I' currently working on a project for that game and I was considering having a custom soundtrack.

Still, very useful/awesome tool! Great job.

[Elektro-Omega]

I have glanced over this thread a few times and never truly appreciated it.

This is incredibly useful and very clever.

Quick question. To make it support Redbook audio was it literally a SEGA CD Flag that you had to set and then told the ROM that if the Redbook audio exists, use that otherwise use the default?

or was it completely different and required a huge amount of reprogramming?

Either way, I'm hugely impressed by what I can see and I cannot wait to see some members using this in their hacks. (I wish I could but I doubt I have the knowledge)

This post has been edited by Elektro-Omega: 11 December 2011 - 01:39 PM

[Hendricks 266]

Elektro-Omega, on 11 December 2011 - 01:39 PM, said:

I have glanced over this thread a few times and never truly appreciated it.To make it support Redbook audio was it literally a SEGA CD Flag that you had to set and then told the ROM that if the Redbook audio exists, use that otherwise use the default?

Nothing low-level like Mega Drive assembly is ever that simple. At the very least they had to edit the sound driver and add CD playback code.

[Iron Sonic]

Elektro-Omega, on 11 December 2011 - 01:39 PM, said:

Quick question. To make it support Redbook audio was it literally a SEGA CD Flag that you had to set and then told the ROM that if the Redbook audio exists, use that otherwise use the default?

or was it completely different and required a huge amount of reprogramming?

There really is a flag for detecting if the Sega CD exists (actually, there are two, but that's for another conversation), but to actually use the Sega CD requires a large amount of Sub CPU code and a bunch of modifications to the game's Main CPU code to make it work properly.

[theocas]

Elektro-Omega, on 11 December 2011 - 01:39 PM, said:

I have glanced over this thread a few times and never truly appreciated it.

This is incredibly useful and very clever.

Quick question. To make it support Redbook audio was it literally a SEGA CD Flag that you had to set and then told the ROM that if the Redbook audio exists, use that otherwise use the default?

or was it completely different and required a huge amount of reprogramming?

Either way, I'm hugely impressed by what I can see and I cannot wait to see some members using this in their hacks. (I wish I could but I doubt I have the knowledge)

Like my colleague stated above, it takes quite a bit of re-programming. To put it in simpler terms - imagine you have a car, but you're odd and decide to change the frame of the car to something different but keep the engine. That's the sort of modifications we've made.

[Elektro-Omega]

Wow. I honestly had no idea it required so much as to rewrite the main CPU code and some sub CPU code to get it to work.

I stand by my previous statement saying that this is incredible and it's wonderful to see things like this are possible.

Do you think this will become a standard in hacks soon? or even become a template for hacks soon?

I like to think of the possibilities but I don't like the idea of people spamming it in every hack. Regardless, awesome work, fantastic.