Many of the sub-gigabyte Conner drives had some version of a 68HC11A or -E on them: this is from personal experience. I have _heard_ that some had 68HC16s and 68HC11Fs.
The HC11A-types had an internal ROM, but it was not used. Many of those I looked at (20 or so) had a version of the BUFFALO monitor on board and a very few had (presumably non-functional) Chrysler Corporation engine-control code. Those with the BUFFALO-monitor can be brought up with the super-special monitor connection (Vague, I know:It's been a long time) and reprogrammed to boot the monitor. Those without the monitor can be used to execute a 256-byte program from EEPROM.
Most of them ran at 2MHz bus-clock and a few later ones at 3MHz.
It would be quite a bit of work to exploit these. The amount of fun is up to you
Wade Hassler