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View topic - NOOB: Building my own Cartridges

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  • Joined: 19 Apr 2019
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NOOB: Building my own Cartridges
Post Posted: Fri Apr 19, 2019 10:58 pm
Hi All, NOOB here!

I am a microsolderer with a passion for retro games. Got bored with doing phones all the time so dug out my old consoles and went on the hunt to buy some to fix and clean up.

I have an interest in PCB design and have just recently got assistance to rebuild an RF module for the SMS2 (to try and keep it looking as original as i can from the back) due to having no schematics available or easy to find!

My next one is to build a SMS game cartridge from board design right up to programming and wondering what is the best way to go about doing this?

I have:
* A friend 3d printing cartridges for me
* another friend printing me new cartridge labels, and
* I have designed a new board and about to send it off for manufacture

Before i send this off though, i need to know what is the best chip to use to program as i dont plan on taking it off the board once its on. I have looked at the SMS R/W Cartridges on here, but not sure if/how i can just use one of these to program the chip and then solder it to an existing board??

Any help would be much appreciated.
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Post Posted: Fri Apr 19, 2019 11:43 pm
You will need a mapper to enable more than 48KB of ROM. There are a few CPLD designs around but none that are widely used yet as far as I know.
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Post Posted: Sat Apr 20, 2019 3:02 am
Maxim wrote
You will need a mapper to enable more than 48KB of ROM. There are a few CPLD designs around but none that are widely used yet as far as I know.


Ive looked at the SMSReader project. It allows creating of a 32K or 256K cartridge. Would that allow me to upload certain games to cartridges?

All VERY new to this side of things
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Post Posted: Sat Apr 20, 2019 8:48 am
Last edited by Maxim on Sat Apr 20, 2019 10:36 am; edited 1 time in total
The CPU can only "see" 48KB of the cartridge memory. It's usual to have a mapper which selects which 48KB is exposed when the cartridge has more. Most games have this functionality on the same chip as the ROM, but some have it on a separate chip. (You will never find flash memory with this functionality.) You can therefore cannibalise old games to get mappers (and boards, shells and boxes), but many would prefer not to. Thus you will need to make some chip with this functionality - and a CPLD seems to be the way to go.

There are many ways you could implement this, but being compatible with the Sega mapper gives you more chance to put real games on there, plus homebrew tends to use it too because that works well with emulators.
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Post Posted: Sat Apr 20, 2019 10:15 am
You have explained this in the best way possible!

Now i just have to find the best chip and how to do it lol!
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Post Posted: Thu May 02, 2019 8:47 pm
you might want to check this too. SEGA mapper VHD by db-elec
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