It is currently Sat Oct 21, 2017 10:51 am

All times are UTC - 7 hours





Post new topic Reply to topic  [ 13 posts ] 
Author Message
PostPosted: Sun Jul 05, 2015 7:37 pm 
Offline

Joined: Sun Jul 05, 2015 7:15 pm
Posts: 5
I think it was mentioned and discussed before.
Phantasy Star 1 was re-released for the Mega Drive in Japan ( G-4534) in 1994 - ( kind of with the PH4 release )
and its Rom on the PCB is actually simply the Sega Master System Rom.

I opened up my cart of PH1 and it indeed holds a different PCB that I usually seen at MD Games.
The Mask Rom :

MPR-16266-F
834011
2A5 AK
9402 T00
( ROM 32pin)

The PCB : 171-6590B

Would it be possible to swap the Maskrom with an eeprom (which one would fit ? )
Of course the simplest way would be buying a Master System adaptor, but still it would
offer a possibility of a English Translated Phantasy Star 1 on a MD Cart.


Top
 Profile  
 
PostPosted: Sun Jul 05, 2015 8:16 pm 
Offline

Joined: Thu Aug 12, 2010 3:43 am
Posts: 1589
I don't see any reason why you can't, as long as the pinout is the same (unless you replace the whole PCB). Setting the console into Master System mode is literally just a matter of wiring a line in the cartridge slot (some other lines get repurposed, but as long as you stick to what that cartridge does you should be safe).


Top
 Profile  
 
PostPosted: Sun Jul 05, 2015 10:20 pm 
Offline
User avatar

Joined: Sat Feb 12, 2005 9:43 pm
Posts: 10065
Location: Rio de Janeiro - Brazil
How does this game handle the pause button?


Top
 Profile  
 
PostPosted: Mon Jul 06, 2015 6:11 am 
Offline

Joined: Thu Aug 12, 2010 3:43 am
Posts: 1589
This game doesn't need pausing ^^; (nothing is dependent on timing so you can just press nothing and the game will just idle)


Top
 Profile  
 
PostPosted: Mon Jul 06, 2015 6:51 am 
Offline
User avatar

Joined: Sat Feb 12, 2005 9:43 pm
Posts: 10065
Location: Rio de Janeiro - Brazil
How convenient. Well, this might be an issue if you replace the game for one that does require pausing then. IIRC, the pause button on the SMS generates an NMI, right? Is that as simple as closing a swich or do you need more complex hardware?


Top
 Profile  
 
PostPosted: Mon Jul 06, 2015 7:09 am 
Offline

Joined: Thu Aug 12, 2010 3:43 am
Posts: 1589
Just a switch which is connected to one of the cartslot pins (that tells the console to generate NMI). That's how the pause button in the Power Base Converter works.


Top
 Profile  
 
PostPosted: Mon Jul 06, 2015 7:29 am 
Offline

Joined: Sun Sep 19, 2004 11:12 pm
Posts: 19114
Location: NE Indiana, USA (NTSC)
Can SMS games read the Start button of a connected Genesis controller? If so, a pause patch would work.


Top
 Profile  
 
PostPosted: Mon Jul 06, 2015 8:09 am 
Offline

Joined: Thu Aug 12, 2010 3:43 am
Posts: 1589
Yes, you can even make them read all the buttons from a 6-pad if you really want to.

Note that this would require expanding a joypad reading routine (it will inevitably happen due to having to read twice for a 3-pad, seven times for a 6-pad) so it would probably require moving code around. And this is before you patch the game to implement pausing through the Start button.

Just make sure to not do what the Master System port of Sonic Blast does (they moved pausing to the 1 button... WTF? - makes sense in context because on the Game Gear the Start button is a proper polled button and not NMI, but still)


Top
 Profile  
 
PostPosted: Mon Jul 06, 2015 2:48 pm 
Offline
User avatar

Joined: Sat Feb 12, 2005 9:43 pm
Posts: 10065
Location: Rio de Janeiro - Brazil
Sik wrote:
Yes, you can even make them read all the buttons from a 6-pad if you really want to.

Do you even need a Genesis/MD for that or can an actual Master System with a Genesis controller do it too?

Quote:
Just make sure to not do what the Master System port of Sonic Blast does (they moved pausing to the 1 button... WTF? - makes sense in context because on the Game Gear the Start button is a proper polled button and not NMI, but still)

Since Sonic uses a single action button, I don't think this is such a big problem. I can imagine people who are used to jumping using the button that now pauses being pissed off, but the convenience of being able to pause without getting up is more than welcome IMO. I'm not talking out of laziness, it's more the fact that the time it takes for you to get up and press the button could end up costing you.


Top
 Profile  
 
PostPosted: Mon Jul 06, 2015 5:50 pm 
Offline

Joined: Sun Mar 19, 2006 9:44 pm
Posts: 915
Location: Japan
barneygumble wrote:
Would it be possible to swap the Maskrom with an eeprom (which one would fit ? )

Many (most) SMS games have a ROM with a built-in memory mapper, so you can't just use an (E)EPROM... unless you want yourself limited to 32k homebrew and such. The forums and info pages at smspower.org have more information.

_________________
http://www.chrismcovell.com


Top
 Profile  
 
PostPosted: Mon Jul 06, 2015 6:33 pm 
Offline

Joined: Sun Sep 19, 2004 11:12 pm
Posts: 19114
Location: NE Indiana, USA (NTSC)
I wonder why Nintendo never did that in the NES and Super NES era. I imagine it would have saved pins to put the mapper in the PRG ROM.

If you're making your own Master System game, you could put in your own mapper circuit, such as a 74HC161+74HC08 or an MBC5 clone or something like that, correct?


Top
 Profile  
 
PostPosted: Mon Jul 06, 2015 6:40 pm 
Offline

Joined: Sun Apr 13, 2008 11:12 am
Posts: 6289
Location: Seattle
I think the only reason to not(?) do that is that there's almost no funny mappers for the SMS, just the "32KiB mapped from 0x0000-0x7FFF" and "three 16 KiB banks mapped in the bottom-most 3/4 of the address space": http://www.smspower.org/Development/Mappers

It would be easy to recapitulate something like NROM-368 using just a single AND gate, though.


Top
 Profile  
 
PostPosted: Mon Jul 06, 2015 7:37 pm 
Offline

Joined: Thu Aug 12, 2010 3:43 am
Posts: 1589
tokumaru wrote:
Sik wrote:
Yes, you can even make them read all the buttons from a 6-pad if you really want to.

Do you even need a Genesis/MD for that or can an actual Master System with a Genesis controller do it too?

Master System can do it too.

Just beware, this works with joypads but not with other accessories which need reconfiguring the I/O lines differently. The Master System has limits on how much you can repurpose them, unlike the Mega Drive where every bit can be input or output.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 13 posts ] 

All times are UTC - 7 hours


Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group