Gameboy Development Forum

Discussion about software development for the old-school Gameboys, ranging from the "Gray brick" to Gameboy Color
(Launched in 2008)

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#1 2020-06-01 08:51:21

alanFJ
New member
From: Tokyo
Registered: 2020-05-23
Posts: 5

Yet another free custom cartridge (32kB only)

Hi everyone,

Following my previous misadventures I'm making a newer better GB cartridge (32kb only - no MBC chip) BUT with a onboard selector so you can have on the same cartridge up to 8 (=2^3) different 32kB games (excellent suggestion of nitro2k01). 
It should work with any "recent" PLCC32 type of EEPROM. The control pins of the EEPROM are accessible via solder pads in case the need to override something.
Basically solder the EEPROM and close the solder-bridges (or solder the SMD switch) and it should be ok (throw in a bypass cap for good measure too).

It's free for use for everyone, but I'll be happy to have comments before sending for production. Truth being told I've wandered through many versions before this one, each time with (luckily fixable) issues on it but none so far worked perfectly. I'd like this one to differ, with you support.
Comments and suggestion most welcome. And I hope it can be useful for you.

Eagle schematics below, pick the "Ultima" version.
https://github.com/AlanFromJapan/pcb-de … artridgeKS

Thanks!
Alan.

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#2 2020-07-07 09:23:31

alanFJ
New member
From: Tokyo
Registered: 2020-05-23
Posts: 5

Re: Yet another free custom cartridge (32kB only)

Hi everyone,

A few weeks later the PCB was received and works just fine out of the box, and if you put an SMD switch you can in fact have up to 8 x 32kB ROM in the EEPROM. You can close the solder bridges but in that case it's just a regular 32kB board.

if you're interested or if helps you, the Eagle schematics are on the github link above for your use. Happy tinkering!
http://electrogeek.cc/files/gbcart-ultima.jpg

Alan.

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#3 2020-07-07 17:02:16

Tauwasser
Member
Registered: 2010-10-23
Posts: 148

Re: Yet another free custom cartridge (32kB only)

Nice job, Alan!

Do you program the EEPROMs externally or when they're on the cartridge?

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#4 2020-07-08 10:11:42

alanFJ
New member
From: Tokyo
Registered: 2020-05-23
Posts: 5

Re: Yet another free custom cartridge (32kB only)

Hi Tauwasser,

Thank you for your kind words.
I program the EEPROM before putting it in the socket (or soldering directly) with a programmer I wrote based on an ATmel microcontroller, or more recently with a TL866II programmer from eBay (way better and way faster).

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