I’d been toying for a while with the idea of making a Megadrive / Genesis Flash Cart to enable new homebrew games to be released on real hardware (similar to De-Bee Card for TG-16). There already exists similar products but they unfortunately are using 3.3V Flash in a 5V system which can lead to all sorts of problems with latch up and clamping diode failure. To keep it short and simple, using 3.3V Flash in a 5V system requires the use of level translators!
Anyway, back to the topic at hand. I decided to use purely 5V parts to avoid any kind of out-of-spec condition in my product. The result: a 16Mbit max (2Mbit, 4Mbit and 8Mbit available as well) with 32KB of save RAM (FRAM or battery-backed SRAM). The Flash parts used are MX29F800 (or MX29F400 – MX29F200) and save RAM is FM1808 (FRAM) or AS6C62256 (SRAM).
MD Flash is NOT an Everdrive nor is it trying to be an Everdrive. MD Flash is modern cart hardware which can be used to release new games in a 5V safe way which gives developers peace of mind about not running the Megadrive / Genesis bus out of spec into clamping diode hell!
I’ve been using a TL866CS EEPROM burner for some time now and have no real complaints about it. This burner has native support for MX29Fx00 parts so I decided I was not going to re-invent the wheel and would not make custom burning hardware. Instead, I simply designed a cartridge adapter which plugs into the TL866CS and converts the 64-pin Genesis cartridge into the 44-SOP pinout for MX29Fx00. There is a jumper on my cartridge adapter to select between upper 8Mbit and lower 8Mbit when my cart is configured for 16Mbit ROMs.
The Motorola 68K CPU is a Big-Endian CPU which means that ROM files you have (but legally shouldn’t ;)) on your PC are not compatible to be directly burned onto MD Flash. The high and low bytes of each word must be swapped. For this, I wrote a quick C# Endian Converter which swaps all bytes in each word and also separates the ROM into two 8Mbit files (upper and lower) if the ROM is larger than 8Mbit. The output files from my Endian Converter can be directly burned onto MD Flash.
If you’re interested in releasing a game on Genesis / Megadrive using the MD Flash hardware, stay tuned to updates on my Products page where I will put up a product page for MD Flash shortly. Exact details on burning arrangements will be worked out on a customer per customer basis. I will absolutely NOT burn repros for you, it must be an original game.