Dreamcast Triple Bios

thanks alot for your reply, but gonna need elaboration on this I guess

 

Thank you. A fourth bios currently is not supported, it is just an idea I tossed around. Making that board would be a tight fit and since there isn't demand for it I haven't built it. Most users likely wouldn't find it useful, maybe someone like japanese cake would find it useful for testing dev builds.

If you meant third, I have my dreamcast setup to be able to switch between Original BIOS, Japanese Cake BIOS, and Dreamshell loader.

I haven't done the triple bios mega cd but there was a discussion on it fairly recently and Damn-Deal-Done did the mod. Here is that thread: https://assemblergames.com/threads/sega-mega-cd-multi-bios-which-switchless-code.70045/

 

thanks for the info , I'll go through it

 

Ground the higher address lines as needed to enable/disable each section of the EPROM.

 

i will go through it

 

An example is the installation of the 256kb flash for the Saturn. The BIOS is 128kb IIRC and you ground the uppermost address line to disable the half that was zero'd out so the Saturn won't read it. Each address line is responsible for a specific amount of the IC's storage.

Don't know the technical specifics but it's that simple 99% of the time.

 

thnx for the info

 

Checked and everything is connected. Maybe the issue is Dreamshell?! I´ve put the content of the build folder from Github into a folder named DS and put this folder on my CF card.

How do you replace bflash.kfl respectively where is your Dreamshell (SD, HDD, CD, CF)?

 

TL;DR I boot from the Dreamshell loader cd, which reads Dreamshell off an SD which is connected via a cheap Dreamcast serial to sd converter, and the only file changed is the latest build of bflash.kfl

Flash Instructions
1. From the Dreamshell website(http://www.dc-swat.ru/page/dreamshell/) download "DreamShell 4.0 RC 4 + Boot Loader"
2. From that archive copy all files within the DS folder onto an FAT formatted SD card
3. Download the latest build of bflash.kfl from the Dreamshell github(https://github.com/DC-SWAT/DreamShell/blob/master/build/modules/bflash.klf) and replace the original on the SD card located at [SDCARD]:\modules\bflash.klf
4. Place the SD card into a Dreamcast SD serial adapter and insert into the Dreamcast serial port
5. From the archive from step 1 burn the DreamShell_boot_loader_v2.4.cdi to a CD-R
6. Place the burned disc in the Dreamcast, make sure your switch is set to boot from original bios, and start the console
[The Dreamcast should boot the disc which will look for the Dreamshell files on the SD card and boot up Dreamshell. This may not work on first attempt, keep trying until the loader boots or reburn to a new disc. This can be temperamental.]
7. Once Dreamshell has loaded, start the Bios Flasher app
8. Switch the Flash chip on
9. Select Detect and verify it detects the flash chip as Model MX29L3211 with Access Read Write
10. Select Write, Select DS, Select BOOT LOADER DEVKIT.BIOS or BOOT LOADER RETAIL.BIOS, and select Confirm
11. Don't touch anything and wait for the Bios Flasher to complete. When complete the app will display Done Writing Successful.
12. Select Ok, power off the console, remove the boot loader disc, and power back on. It should now start the Dreamshell loader from flash, read Dreamshell from the SD and boot.

 

And it doesn't matter if Pin44 of MX29L3211 is grounded or connected via 10k resistor to3.3V during flashing, cause with this you only choose which half of the chip you write on?!

 

Correct. It should not matter which it is pulled to as long as it is stable during writing. Is the software detecting the chip as MX29L3211 with Access Read Write in step 9? Did you only switch to the latest build for bflash.kfl or are all the latest modules on your SD card?

Here is the schematic: