[userbinator]

Pretty much every microSD card has had an ARM cpu core in it since forever

A lot of them use 8051, presumably because it's cheaper and smaller: https://www.bunniestudios.com/blog/?p=3554

[consp]

I've worked with TI BLE chips which were 8051 variants. Took me back to original CS classes as it is a very simple core with limited registers but can still be used to perform all the bluetooth functions.

[trevyn]

IIRC, the BLE stack on those was a separate (undocumented?) core; the 8051 was for user software that gave high-level commands to the BLE block through magic registers. Still fun to program, for sure.

[ChuckNorris89]

The older ones for sure, but all the modern ones have moved to ARM7-TDMI then to Cortex-Mx cores.

[makomk]

Some of the more, ah, cost-reduced Bluetooth chips have 8051s or all kinds of weird, proprietary processors, presumably because the per-chip licensing fee for ARM is too much at that end of the market or something.