32MB RAM Expansion

Discuss modifications you have done or plan to do to your Dreamcast or any other hardware, or discuss devices you want to build. If your console does not work or is acting up, ask about fixing it in here.
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32MB RAM Expansion

Post by |darc| » Sun Jun 21, 2020 9:53 pm

Thought you guys might enjoy this. Someone has gotten 32MB RAM running on the Dreamcast :)

https://tsowell.github.io/2020/06/21/dr ... grade.html
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Re: 32MB RAM Expansion

Post by |darc| » Mon Jun 22, 2020 2:42 pm

For those attempting to do this, I have uploaded an updated DreamShell CDI image with nearly 50 different BIOS images in a variety of flavors: DreamShell 32MB Flasher
Includes stock BIOS images, Link83, japanese-cake, DreamBoot, DreamShell, etc. A list of BIOS images included here!
This image also contains an updated bflash.klf module to support flashing the MX29L3211 32 megabit chips to accommodate triple-BIOS mods!

Just note before you use this disc that I HAVE NOT TESTED ANY OF THE 32MB HACKED BIOS IMAGES! I simply blindly patched the required bytes in all BIOS images, with no testing at all. I have no idea if any of the other BIOS images will work, especially dreamboot, dreamshell, etc. Make sure you have a backup plan or way to recover your Dreamcast BIOS if you flash one of these and it doesn't work! I plan on doing the mod when I get back from 4th of July vacation. jc-v1.032-32MB.bin has the same sha1 as tsowell's firmware hack so that one should work.
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Re: 32MB RAM Expansion

Post by |darc| » Thu Jun 25, 2020 3:55 pm

I now have a 32MB RAM Dreamcast! :D I actually got around to getting this done before pulling out for vacation. I had to take a risk in doing a piggyback BIOS install instead of a triple BIOS since my PCBs haven't been made yet -- if any of the BIOS images with 32MB patches didn't work, the DC would have been bricked and I would have had to do some soldering to get things working again.

Luckily, everything I tested WORKS!* I gave my bootROM a good working out today.
(*By "works" I mean the Dreamcast boots up and I am able to launch Crazy Taxi or DreamShell.... I didn't do super extensive testing for each BIOS)
EDIT: Uh oh! Sonic Adventure crashes when loading and Phantasy Star Online v2 crashes when going to the FMV!!! Crap.
Good news is that it is possible to put the pins on a DPDT switch and turn the mod on and off.

Code: Select all

1.004 vanilla						UNTESTED, PROBABLY WORKS
1.01c vanilla						UNTESTED, PROBABLY WORKS
1.01d vanilla						WORKS
1.01d w/ region free patch ("link83")			WORKS		
1.01d w/ region free patch alt intro ("link83")		WORKS
1.01d Treamcast						UNTESTED
1.022 ("no mil-CD BIOS")				NOT INCLUDED ON DISC, UNTESTED
jc 1.300 regular intro					WORKS
jc 1.310 regular intro					WORKS
jc 1.310 alt intro					WORKS
jc 1.032 regular intro					WORKS
jc 1.032 alt intro					WORKS
dreamboot 1.0.0						WORKS
dreamboot 1.0.0 No GD-ROM				UNTESTED, SHOULD WORK
dreamboot 1.0.1						WORKS
dreamboot 1.0.1 No GD-ROM				UNTESTED, SHOULD WORK
dreamboot 1.0.2						WORKS
dreamboot 1.0.2 No GD-ROM				UNTESTED, SHOULD WORK
dreamboot 1.1.0						WORKS
dreamboot 1.1.0 No GD-ROM				UNTESTED, SHOULD WORK
dreamshell boot_loader regular intro			WORKS				
dreamshell boot_loader regular intro No GD-ROM		UNTESTED, SHOULD WORK
dreamshell boot_loader alt intro			WORKS
dreamshell boot_loader alt intro No GD-ROM		UNTESTED, SHOULD WORK
dreamshell sd_loader_with.bios				WORKS
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Re: 32MB RAM Expansion

Post by APE » Fri Jul 31, 2020 8:27 pm

Can't figure out my original account's password, think it's tied to a dead email address I turned off. Any chance you can change the password or the associated email address?

If you want a triple BIOS board I have a few unpopulated ones. Have all the parts, will send to you at cost. But it's been over a month so I'm guessing you got the parts.

Aside from the cool factor has anyone made anything to utilize the extra RAM? Or found out why some games aren't compatible with it? I'd be happy to build a few consoles to giveaway to devs if it mean they would look into this.
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Re: 32MB RAM Expansion

Post by |darc| » Fri Jul 31, 2020 9:40 pm

APE wrote:
Fri Jul 31, 2020 8:27 pm
Can't figure out my original account's password, think it's tied to a dead email address I turned off. Any chance you can change the password or the associated email address?
I swapped the email addresses on the two accounts, you should be able to activate the APE account with the new email.
APE wrote:
Fri Jul 31, 2020 8:27 pm
If you want a triple BIOS board I have a few unpopulated ones. Have all the parts, will send to you at cost. But it's been over a month so I'm guessing you got the parts.
Appreciate it but unfortunately the triple BIOS board covers up one of the RAM chips so the 32MB RAM mod has to be done first.

I got my boards in but haven't had the time yet to re-do the mod with it.
APE wrote:
Fri Jul 31, 2020 8:27 pm
Aside from the cool factor has anyone made anything to utilize the extra RAM? Or found out why some games aren't compatible with it? I'd be happy to build a few consoles to giveaway to devs if it mean they would look into this.
Unfortunately so far no one has made anything except the ScummVM build that uses it, and the memory testing application.
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Re: 32MB RAM Expansion

Post by APE » Fri Jul 31, 2020 10:05 pm

Word, got my account back.

Didn't know that about the mod, haven't done the triple yet.

Shame but it's a start. It's only been a month here.
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Re: 32MB RAM Expansion

Post by |darc| » Fri Jul 31, 2020 10:08 pm

I was editing the post while you posted, lol. But I meant to add:

A lot of games have problems running with the mod, so it has to be put on a switch.

Pins 21 and 22 on both chips are connected together, so you should be able to just wire it up with a DPDT switch:
  • For 16MB mode wire both pins 21 together and connect them to ground; wire both pins 22 together and connect them where pin 22 usually connects.
  • For 32MB mode, wire both pins 21 together and connect them to where pin 22 usually connects; wire both pins 22 together and connect them where pin 23 connects.
Both of these pads also connect to visible vias near the RAM chips, so you have multiple points you can solder to, but the vias are pretty small and annoying to solder.

Since the triple BIOS board covers the RAM chips, you should install like so:
  • Remove stock RAM chips
  • Bend pins 21 and 22 up on new RAM chips
  • Solder new chips in place with pins 21 and 22 lifted
  • Wire new chips up using a DPDT switch
  • Boot console in 16MB mode and run memtest to verify RAM is soldered properly because this is the last time we can access the RAM on the right
  • Add triple BIOS board, covering up the right-side RAM
  • While in 16MB mode, boot DreamShell BIOS Flasher disc with 32MB-patched BIOS images I made
  • Load up BIOS flasher, flick triple BIOS switch to a writable BIOS bank, write a 32MB-patched BIOS image
  • Turn off console, change RAM mode to 32MB
  • Boot console and verify with memtest that 32MB RAM is working and seen
  • Enjoy ScummVM games with large RAM requirements
I'm not an expert in using any of the PCB design software, but it would be cool if the triple BIOS board with the switching IC were modified so that there were pads for the pins 21/22 of RAM so that the stock bank and bank 1 switch the RAM to 16MB mode and bank 2 switches the RAM to 32MB via one switch.
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Re: 32MB RAM Expansion

Post by APE » Mon Aug 03, 2020 11:52 am

That should be an easy change on that PCB. At this point I don't see much else need for triple BIOS support except for anyone doing dev work with dual compatibility in mind.
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Re: 32MB RAM Expansion

Post by Arvex » Thu Aug 20, 2020 8:17 pm

Would I be right to guess that extra 16MB of RAM would be useless for retail Dreamcast games? My intuition tells me it would only be usable if you're trying to boot Sega Naomi ROMs (similar RAM expansion mod exists for the original Xbox to run Sega Chihiro games since they're almost identical hardware) on it or for homebrew games specifically made to use that extra RAM.
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Re: 32MB RAM Expansion

Post by |darc| » Fri Aug 21, 2020 4:02 pm

Arvex wrote:
Thu Aug 20, 2020 8:17 pm
Would I be right to guess that extra 16MB of RAM would be useless for retail Dreamcast games? My intuition tells me it would only be usable if you're trying to boot Sega Naomi ROMs (similar RAM expansion mod exists for the original Xbox to run Sega Chihiro games since they're almost identical hardware) on it or for homebrew games specifically made to use that extra RAM.
I imagine it will be useless for retail Dreamcast games, although perhaps it would be possible to fix something like the unreleased leaked Heroes of Might and Magic III which has out of memory problems.

The Naomi has twice the VRAM and four times the sound RAM as the Dreamcast, so unfortunately it won't be very useful for running Naomi games on the Dreamcast.

Because it's shown to have compatibility problems with existing retail games, and because ScummVM is the only homebrew which supports the mod, I don't imagine it will be very popular, although I really hope homebrew authors include features for it in the future.
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Re: 32MB RAM Expansion

Post by YZB » Fri Oct 09, 2020 3:12 am

I made a kof98 that needs 32M memory to run,

welcome to test, it can be burned or run on gdemu or mode

Warning, dreamcast with 16M RAM does not work

https://mega.nz/file/0aw0nKZB#BI-jp8fIk ... EgN05MjtDY
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Re: 32MB RAM Expansion

Post by |darc| » Fri Oct 09, 2020 1:29 pm

Awesome! Thanks YZB! I will have to check this out when I get some time!
From the readme:
Part of the game files are stored in the memory, and the game runs faster (it will be obvious if it is read by CD) I won¡¯t talk about some minor changes.
BTW I love your Saturn RAM cart hacks! I have them on my Saturn with Fenrir ODE :)
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Re: 32MB RAM Expansion

Post by Arvex » Fri Oct 09, 2020 3:45 pm

|darc| wrote:
Fri Aug 21, 2020 4:02 pm
I imagine it will be useless for retail Dreamcast games, although perhaps it would be possible to fix something like the unreleased leaked Heroes of Might and Magic III which has out of memory problems.
Depending on how it manages memory, you might have to modify the game so it even knows there is more RAM available. It would be cool seeing someone take that unfinished game and not only finish it, but see if there is room to add in the Armageddon's Blade and/or Shadow of Death expansions (HoMM3 Complete is just over a gigabyte installed on my PC, so it might be possible with some compression.)
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Re: 32MB RAM Expansion

Post by YZB » Sat Oct 10, 2020 6:19 am

I made 2 videos, both of which were burned to cdr and read on dreamcast



1 The original game has not been modified, it is suitable for dreamcast with 16M memory

https://www.bilibili.com/video/BV1mz4y1d7um/



2 32M dreamcast is used, and the game has been modified and optimized a lot

https://www.bilibili.com/video/BV14p4y1Y7bE/


3 Use gdemu to read the original gdi, 4Gsdhc memory card
https://www.bilibili.com/video/BV1at4y1v7bH/



4 Use gdemu to read 32M memory version of gdi, 4Gsdhc memory card
https://www.bilibili.com/video/BV1HV41127sT/
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