Which ARM Microcontrollers are embedded in current SD Cards? The Motorola 8051 tends to get mentioned in this connection, with occasional, vague references to ARM. So, which specific ARM technologies are used for this purpose, and what kind of embedded OS do they use? Linux has been mentioned in this connection; do ARM SD implementations use it? If so, which disto(s)?
From the paragraph, it looks like Dave Hughes recommended an ARM Cortex-M4 for enhanced ECC made on the MCU.
The ARM Cortex-M4 has additional DSP instructions (not a "secondary DSP core"). Some ECC algorithm might benefit from these additional instructions. These additional instructions take die area, so production cost is higher. I don't think this matters for a single home-made one, but I think any cent/penny has a major impact to the bottom line when you churn millions of them.
Also, at the time of the article, I don't believe the ARM Cortex-M0+ existed.
Here is attached an old table showing which instructions are supported by which core.
That's quite some little sketch, Alban! It does show the capabilities of the -M4 in this context, and it's tempting to think of it as a bit of a steamroller. The thing is, though, that the SD wallnuts are getting bigger and tougher all the time. The latest, high-quality 128GB versions retail at up to £90-plus hereabouts; that's SSD territoty, and the cost of an -M4 chip can easily be absorbed in those numbers. And, if Dave Hughes and his people are using them, then there's obviously a market out there. Here's a terrifying thought; the theoretical maximum capacity for an SD Card is 2TB......