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  • Joined: 11 Mar 2006
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Master system converter problem
Post Posted: Thu Aug 29, 2019 6:57 pm
Last edited by gorgyrip on Thu Aug 29, 2019 9:39 pm; edited 5 times in total
I've made a converter to play master system games on megadrive.
I used this schematic:
https://atariage.com/forums/uploads/monthly_03_2008/post-7533-1206288018.jpg

The problem is with wonderboy in monster land.
-on a MD2 PAL it plays fine - modded with a variation of seb's code:http://wolfsoft.de/wordpress/?p=541
-on a few other PAL MD2 consoles it works if I start another game before it. But it does not always works. Modded with seb's switcheless code
-on another PAL MD2 it doesn't work at all. Not modded.
-on another PAL MD2 Asia Version it doesn't work at all. Not modded.
Note: wonderboy in monster land is made from an after burner cart. But if I flash other games on it, they work on all consoles.

So why wonderboy works only on a few consoles?

EDIT: Found another one that behaves the same. Assault city light phaser version (official cart)
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Post Posted: Thu Aug 29, 2019 7:46 pm
Please define "does not work".

Wonder Boy in Monster Land is one of a few games with known controller issues on Mega Drives (even with official Power Base Converters), so you might be experiencing that. Please give it a try with a Master System joypad if you didn't already.
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Post Posted: Thu Aug 29, 2019 7:50 pm
Tom wrote
Please define "does not work".

Wonder Boy in Monster Land is one of a few games with known controller issues on Mega Drives (even with official Power Base Converters), so you might be experiencing that. Please give it a try with a Master System joypad if you didn't already.


It doesn't boot.
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Post Posted: Thu Aug 29, 2019 7:55 pm
If you can flash any game of your choice, please try these:
  • Alien Syndrome
  • Bomber Raid
  • Great Volleyball
  • Montezuma's Revenge
  • Penguin Land
  • Shanghai
  • Tennis Ace
  • Where in the World is Carmen Sandiego?
  • Wonder Boy in Monster Land
As far as I know, these are all the games with controller issues on Mega Drives, so you might experience similar problems.

With all that said, I'm not an expert at all about this, so I'm unlikely to reply again in this topic, I only wanted to provide the simplest kind of first aid, but I'm sure that someone better will reply eventually.
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Post Posted: Thu Aug 29, 2019 11:42 pm
gorgyrip wrote
on a few other PAL MD2 consoles it works if I start another game before it. But it does not always works.


Some games dont initialise the system and rely on the sms bios having done it first. As the megadrive/genesis has no bios those games wont work. In this case i imagine that is why booting a working game first then switching to wonder boy solves your issue.

The official power base converter had a small chip in it that set the z80 stack pointer before booting the game.

This project ( link below ) has a bit of info about it. Its a slightly different adapter but the same principal and you should be able to use the same method.

https://www.raphnet.net/electronique/markIII_to_smd/index_en.php
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Post Posted: Fri Aug 30, 2019 4:47 am
I’ve recently created schematics for both the Powerbase and Mega Adapter if anyone want me to post PDFs of them.
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Post Posted: Fri Aug 30, 2019 8:40 am
Enforcer wrote
I’ve recently created schematics for both the Powerbase and Mega Adapter if anyone want me to post PDFs of them.


I wouldnt mind a look at them if you have time to post them. Was curious about the mega adapter but didnt really want to pay the prices they go for on ebay just to have a look.
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Post Posted: Fri Aug 30, 2019 9:37 am
Enforcer wrote
I’ve recently created schematics for both the Powerbase and Mega Adapter if anyone want me to post PDFs of them.


That would be really great. Then i could compare them with my schematic.

Wasup, I know about that link on raphnet. There's also a code for atmega8 to accomplish that. But i never compiled a code and I'm out of soldering wire. But I will try that.
Since this is bios related, I'm curious is why those 2 games work on some consoles and on other consoles they don't work. Could a switchless mod influence the boot process?

I also found this (last post):
http://www.sega-16.com/forum/showthread.php?27244-How-to-build-a-Master-System-C...

It shows a mod to make wonderboy 3 work. But I can't figure it out. And I don't know if that will fix my problem.
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Post Posted: Fri Aug 30, 2019 10:37 am
That seems to be a way to signal on the reset line on power up, some games need that to reset the mapper; I seem to remember that Codemasters games need this to function too.
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Post Posted: Fri Aug 30, 2019 11:03 am
Maxim wrote
That seems to be a way to signal on the reset line on power up, some games need that to reset the mapper; I seem to remember that Codemasters games need this to function too.


So for the perfect converter I'll need the raphnet's stack initialization plus the reset mod?
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Post Posted: Fri Aug 30, 2019 12:57 pm
gorgyrip wrote
Maxim wrote
That seems to be a way to signal on the reset line on power up, some games need that to reset the mapper; I seem to remember that Codemasters games need this to function too.


So for the perfect converter I'll need the raphnet's stack initialization plus the reset mod?


Stack Init. is only needed for 2 games IIRC: Shadow Dancer and Aerial Assault. If you don't ever plan on playing those 2, then forget about that mod. (My memory is bad - there might be another game, but it's not well known and definitely not WBML)

best regards,
- dink
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Post Posted: Fri Aug 30, 2019 2:35 pm
dink wrote

Stack Init. is only needed for 2 games IIRC: Shadow Dancer and Aerial Assault. If you don't ever plan on playing those 2, then forget about that mod. (My memory is bad - there might be another game, but it's not well known and definitely not WBML)

best regards,
- dink


I didn't know there are only 2-3 games that need stack initialization. That means the problem is with the reset pin or within the schematic.
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Post Posted: Sat Aug 31, 2019 9:30 am
Ill have a dig around and see if i can find my copy of wonder boy in monster land and experiment with it. If its a reset issue a simple reset generator might work fine, which is probably whats used in the picture on that forum post.
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Post Posted: Sat Aug 31, 2019 12:55 pm
wasup wrote
Ill have a dig around and see if i can find my copy of wonder boy in monster land and experiment with it. If its a reset issue a simple reset generator might work fine, which is probably whats used in the picture on that forum post.


Thank you. If it's a reset issue, is it ok to use this?
https://www.aliexpress.com/item/33042652593.html?spm=a2g0o.productlist.0.0.27de6...
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Post Posted: Sat Aug 31, 2019 10:03 pm
Something like that should be fine.
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Post Posted: Sun Sep 01, 2019 8:34 am
wasup wrote
Something like that should be fine.


I opened the Assault City cart. It doesn't have a reset pin.

Are my connections ok?
sms11 (M0-7) + sms36 (A15) ->MD_B17(!CE_L)
sms13 (CRTOE) -> MD_B6 (A18)
sms2 (WR) -> MD_B28 (!WR_L)
sms4 (ROM/RAM) -> MD_B16 (!OE)
sms46 (RST) ->vcc

MD_B9 (A21) ->vcc
MD_B10 (A22) ->gnd

I have also tried that, but no change (from db_electronics):
"Also, on my converters, I don't connect MD pin nCE to both M0-7 and A15 of the Master System. I instead do:
nCE -> M0-7
A16 -> A15"

EDIT: I've flashed wonderboy 3 and this one is working on all consoles.
EDIT2: On raphnet there's a small list of games. I flashed them to may cart and tested them:
Stack pointer ok: kenseiden, lord of the sword, world games
stack pointer not setup: aztec adventure, r-type.

The pattern remains: the ones marked ok work on all consoles from the first try.. And the ones marked not setup work from the first try on the consoles with the modified switchless code. On the console with seb's switchless code they need swapping. And on the unmodified console they don't work. So nothing new until now.

Now I tested Shadow Dancer. Now things gets weirder. It doesn't work at all on the console with the modified switchles mod. Until now that console run all games. But it works without swapping on the console with seb's code.
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Post Posted: Sun Sep 01, 2019 11:59 pm
gorgyrip wrote
The pattern remains: the ones marked ok work on all consoles from the first try.. And the ones marked not setup work from the first try on the consoles with the modified switchless code. On the console with seb's switchless code they need swapping. And on the unmodified console they don't work. So nothing new until now.


I dont see why those mods should make any difference.. your only changing video modes and or region of the console. That shouldnt really effect the how game loads.. unless its pulling the system reset pin just after power up and causing something different to happen.
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Post Posted: Mon Sep 02, 2019 11:55 am
wasup wrote

I dont see why those mods should make any difference.. your only changing video modes and or region of the console. That shouldnt really effect the how game loads.. unless its pulling the system reset pin just after power up and causing something different to happen.


That's beyond my understanding, but the mods have some influence.

I tried raphnet initialization circuit from here:
https://www.raphnet.net/programmation/md_sms_stack/index_en.php
And I'm very happy to report that all those previous games that had problems now work from the first try on all consoles!

But can you please confirm that i did this correctly?
1. Compiling. I installed winavr. I extracted main.c and makefile in a directory. I typed "make" in a cmd window i got the hex file. I programmed the atmega8 using the fuses from the makefile: HFUSE=0xd9 and LFUSE=0xDf
2.In the schematic the RD is connected between atmega and sms. But I've kept the connection also with the MD B_6(A18).


3. Is it ok to replace the crystal and the 2 caps with CSTCE16M0V53-R0?
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Post Posted: Wed Sep 04, 2019 9:26 am
Ive had a bit of a play and wasn't able to find anything odd.

On a Model 1 genesis with a power base converter wonder boy 3 and wonder boy in monster land both work fine. Obviously the power base converter is doing the stack init.

Using a generic master mega converter (the ones that have "game adapter" molded into the cart shell) both games also work fine. This adapter definitely does not do stack init or have a reset generator.

Ive also taken both games apart and checked if they use the reset pin, and neither do. Both games have integrated mappers, possibly there is a variant that has a separate mapper which needs the reset pin?

I havn't got a model 2 console handy at the moment so wasn't able to test on that, so results may be different there.
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Post Posted: Wed Sep 04, 2019 5:22 pm
Thank you.
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Post Posted: Sun Sep 08, 2019 2:07 am
Schematics as promised. Sorry For the delay.
Powerbase.png (160.44 KB)
Powerbase.png
MegaAdapter.png (144.41 KB)
MegaAdapter.png

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Post Posted: Sun Sep 08, 2019 10:50 am
Enforcer wrote
Schematics as promised. Sorry For the delay.


Thank you. I spotted a few differences:
sms36 (A15) - MD_a14 (A16)
sms11(!M0-7)- MD_b17 (!CE0)

on the schematic I used: sms36 (A15) + sms11(!M0-7)=MD_b17 (!CE0)

I tried before your way and no change.


sms5(!M8-B) - MD_b21 (!CAS2)
On mine this connection does not exist. But on my carts this pin is missing.

On your schematic sms46 (RST)=NC
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Post Posted: Sun Sep 08, 2019 11:19 am
Enforcer wrote
Schematics as promised. Sorry For the delay.


Thank you!

Pin va21 on the console side is interesting. It looks like its used to detect when a cart is plugged in. Maybe to detect a card vs cart for some reason, even it doesnt have the ability to switch between them.
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Post Posted: Sun Sep 08, 2019 5:23 pm
My guess is then that is detecting a cart, the chip enables for the card aren’t sent via VA17 so you don’t have a bus conflict.
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Post Posted: Sun Sep 08, 2019 7:25 pm
Enforcer wrote
My guess is then that is detecting a cart, the chip enables for the card aren’t sent via VA17 so you don’t have a bus conflict.


Your right. Thats rather cleaver.
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