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 Post subject: TSROM advice/guidance?
PostPosted: Fri May 13, 2016 8:25 am 
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Joined: Mon May 02, 2016 6:12 pm
Posts: 7
Greetings everyone!

I decided to make a TSROM conversion with sockets. Unlike NROM, TSROM seems to be a bit more complex.
I am confused about the PRG and CHR roms.

I have Bo Jackson Baseball, the PRG is 28 pin, the CHR is 32.
I have 27c256's.

I noticed the PRG has 4 extra pads on the board like a 32 pin rom would work there.

So my question is, would a 28 pin rom work for both PRG/CHR?
If I socket the board for 32 pin rom, but use 27c256s for instance, would that work?

Or do I need 27c040 for CHR for it to work?

Thanks, it is greatly appreciated.


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PostPosted: Fri May 13, 2016 10:14 am 
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Joined: Fri Jul 04, 2014 2:34 pm
Posts: 340
For a proper TSROM cart you should use a game that got 32 pins for both, CHR and PRG.

Rewire like this:
PRG socket:
Bend up pins 1, 2, 24, 30 and 31
Solder pin 2 to hole 24 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to hole 1 (A17)
Solder pin 31 to hole 2 (A18)
CHR socket:
Bend up pins 1, 2, 22, 24, 30, 31
Solder pin 2 to hole 24 (A16)
Solder pin 22 to hole 31 (CE or CHR /A13)
Solder pin 24 to hole 2 (OE or CHR /RD)
Solder pin 30 to hole 1 (A17)

Only a very few games use less than 64kb CHR, so 27c010 / 27c020 or 27c040 are your way to go in any case to make sure everything works.


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PostPosted: Fri May 13, 2016 10:27 am 
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Joined: Sun Apr 13, 2008 11:12 am
Posts: 8533
Location: Seattle
All NES cartridges with ROMs larger than 64 KiB used this pinout.

Famicom cartridges manufactured by not-Nintendo with ROMs larger than 64 KiB used the standard pinout instead.


Do be careful; a 27C256 only holds 32 KiB.


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PostPosted: Fri May 13, 2016 12:33 pm 
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Joined: Mon May 02, 2016 6:12 pm
Posts: 7
Ice Man wrote:
For a proper TSROM cart you should use a game that got 32 pins for both, CHR and PRG.

Only a very few games use less than 64kb CHR, so 27c010 / 27c020 or 27c040 are your way to go in any case to make sure everything works.


lidnariq wrote:
All NES cartridges with ROMs larger than 64 KiB used this pinout.

Famicom cartridges manufactured by not-Nintendo with ROMs larger than 64 KiB used the standard pinout instead.


Do be careful; a 27C256 only holds 32 KiB.


I see, so a 28 pin PRG is isolated to fewer titles in comparison.
If you wanted to repro Bo Jackson Baseball, could you use 27c010/20/40 on PRG socket?
because I intend to install 32 pin sockets, although I lack the proper IC at the moment.
I havent looked at any PRG or CHR files to determine size. Just got a tsrom board and sockets.
I probably should have done that eh? ;D

Thank you both for the info, the shared knowledge is really appreciated. As well as the link to pinout. That will be helpful. : D


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