Why make another cart?

There are a bunch of carts on the market, but for making music, I’m not really happy with any of them - needing something that is reliable, and simple.

Some require an external programmer/reader. These are vulnerable to bad connections; since there are no checksums on save memory, there’s no way to tell if your data has been silently corrupted.

Many carts have instead a programmer built in, using USB. One thing these all have in common is that they require custom software and drivers to be installed, which is a lot of fiddling, and gets very complicated if you’re not on Windows.

Why isn’t it bigger, faster, cheaper…?

This cart was designed with a particular use case in mind - making music.

The design aesthetic I have employed is to make the hardware as simple and reliable as possible. It does one job only; I have resisted the tendencies to pack in features. Simplicity is the aim of every design choice; even the PCB is laid out on two layers, where for this density a modern engineer would usually go straight for 4.

Couldn’t you have made it take an SD card?

A sensible SD cart would have to have:

  • a bootloader that runs on every boot, to load
  • a DRAM chip and controller to hold the ROM, and
  • a mechanism to write changed save data back to SD in real time

Without going into detail, this method is complicated. I considered this path, and did design studies of what would have to happen (and how fast) for this to work.

I decided that this was not the cart I wanted to build.

Does it support LittleFM?

Yes (as of 2013).