Posted January 23, 2022 by Artemio
#Sega Genesis #Sega CD #Mega Drive #Mega CD #BIOS #Hardware
It has been a while since I've wanted to release this version, and it has a lot of changes.. many of which were done last night.
It is hard to balance releases, I don't want to constantly push changes that feel minimal, and the other extreme is to never push any because they are many. And this time I bundled a lot of them. It seems that these things should be static, but they aren't. They are in constant change: bug fixes, new patterns, collaborations, suggestions, quirky details, new ideas... you name it. I will not mention the full change log, since a lot of it was under the hood and probably nobody else but myself cares about how I cleaned up the Sega CD assembly routines and use. But there are a lot of changes that are more relevant than that.
It took us a lot of time, I know. But it was worth it, we now have a PAL monoscope pattern by Keith Raney which has even helped confirm a correction made on the MiSTer FPGA core by birdybro when in PAL mode along with MDFourier, since the timing affected both video and audio.
Keith made an awesome job with this, and I am sorry I have delayed the release of this for even longer due to all my other changes. We didn't have access to a PAL Mega Drive, and had to make do with a modded unit I had and finally got confirmation with MiSTer. Testing on a real PAL Mega Drive would be appreciated.
Obviously Donna by Pepe Salot is finally in this public release, she's been in the Genesis version for months but when I spoke with José back then he mentioned something that echoed with my reasoning regarding small change logs. He didn't want the release to just be about Donna, I reassured him that there were a ton of other changes, and I we were in the middle of adding the PAL version of the monoscope. José's art looks really beautiful and this was worked on by himself to look good with the Genesis palette on a CRT, you should checkout his print store (linked above from his name).
First, the Genesis version has a little promoted and used mode to test hardware, which includes Z80 RAM, a memory viewer, a controller test, Sega CD RAM (Work and Program), Sega CD communication registers and a Sega CD BIOS identification option.
I'll make a post detailing these tests, or an entry in the wiki. I believe they are an important resource for modders and repair technicians. I wrote them for my own use and at the suggestion of Leo Oliveira.
However, they have been useful already twice this past 12 months. The BIOS ID tool checks for the CRC of known dumps and reports either the version inside the system or that it is an unknown/undumped version. And this last year two new dumps were made thanks to it and sent to the MAME team. I'll report the details in the next post due for the end of the month.
That's the regular output when the BIOS is detected. And this new version that you can now download includes both dumps. Thankfully Everdrive carts can now dump the BIOS and that makes this process so much easier. There are some details regarding HINT and using a cart vs the Sega cd, but both are accounted for by the tool. If you are interested in my tool that detects this in ANSI C for you to compile, it is here.
It also has a controller test, and it has been expanded to use the multitap from Sega, and up to 8 controllers. There are even some options for it under the options menu, including a hidden option to check the internal values for emulator developers. This has been tested on Model 1 and Model 2 systems. In order to access the "debug" version, go into options and press C when selecting the "auto-sort controller" option, that will unhide the debug option for you.
You'll notice there are two versions of the suite in the zip now, one for use in regular systems and one for use in emulation or systems that enable Sega CD hardware by checking the header.
This is because in carts like the Everdrive Pro when you want to diagnose a Sega CD attached to the unit with the ROM, you don't want to enable the FPGA Sega CD in the cartridge. But in case that a developer wants to run these tests on their emulated system, the ROM will help them if they check for that to enable the Sega CD.
I also added an ASCII mode instead of just hexadecimal to the memory viewer, this helps navigate teh data easier in some cases.
Below is part of my list of commit changes, if anybody is interested in details regarding those please let me know and I will be happy to detail them further.
- Changed Audio Sync Test to be active for just one frame (Was 2)
- Added PAL Monoscope test
- Fixed gray referenced color bars and reduced their memory footprint
- Made 100% bars the default for EBU/SMPTE
- Can respond to any controller instead of just joystick 1
- Fixed Reflex & timing test to warn user and show proper frame rate
- Removed random PCM sample loading in Sega CD Soudn Test
- New Sega CD detection by /DISK as suggested by Leo Oliveira
- Cleaned and updated Sega CD assembly
- Sega CD now loads correct number of sectors for PCM files
- Fixed Sega cd makefie to properly pad binaries for sector alignment
- Added fixchecksum and trimiso ANSI C implementations
- Cleaned ROM header
- Reduced ISO sizes
- BIOS CRC detects issues under MSU enabled Retroarch cores and patches for them
- Added wait for CD BIOS commands (most probably not necessary)
- Added PCM info to help for Sega CD