Motorola MPC850

On a lighter, and more interesting note, I’ve been discovering the inner workings of BDM ports on Motorola processors. It all started when this useless DirectvDSL modem showed up on my desk at work. It’s useless because the firmware is hardcoded to work only with DirectvDSL and since they’re no longer operational, it’s basically a brick. Opening it up, I discovered a MPC850 processor, 4 MBytes Flash, and 16 MBytes of RAM. It would make a nice embedded systems project. I traced out the debug port which turned out to be BDM instead of JTAG, although they are very similar. I built a BDM interface and it works. After figuring out how to use the BDM support in GDB (GNU Debugger), I’m finding myself getting into the inner workings of the processor and what makes it tick. I’ve only ever dealt with 8-bit micros before, but this 32-bit thing is something else. Maybe it’s just overwhelming because this processor is capable of so many other things. If you’re knowledgable on the MPC8xx/5xx processors, I’d like to hear from you. I have some questions.

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