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).