The question arises because all Cortex-M series ARM chips have the 'Debug Peripheral' built in, it should be possible to build a front panel that connects to that and you could program/operate the machine from the front panel. 2/2
#arm #computing #design
I've been delighted with what Black Magic Probe can do with that Cortex-M debug port. Via GDB, you can do all the stuff I used to do with front panel switches: Single instruction, register dumps, view and edit memory, etc...
Now, BMP actually implements the GDB Server API over USB serial... Seems like it would be easy to build a physical front panel that issued those commands behind the scenes...
@zero I've been a huge fan of the BMP since it came out, even have a couple of contributions to the repo (got the Atmel SAMD code working), it was kind of my inspiration here. I thought, what if you used something with more ram/io for control, and then a bunch of lights/switches/displays for the panel. What would that look like? And yes, you can completely operate and look at any part "inside" the CPU with SWD and trace.
@ChuckMcManis Here's my JTAG debugger.
@larsbrinkhoff Its so pretty. And I could probably still use it to bring up TOPS-20 (or TENEX) if I had it. The PDP-10 Replica is fun too.
@ChuckMcManis Joking aside, the JTAG debugger I'm using right now does allow displaying registers and memory contents in real-ish time. So of course it would be entirely possible to do this much more stylishly with a blinkenlights panel.
@larsbrinkhoff Yeah, the trace unit in the Cortex-M architecture is pretty powerful. You can have it sampling a register in "real time" which would work well for this.
@ChuckMcManis The PiDP-10 does run TOPS-20 which is kind of disconcerting to see on a KA10 panel.
TENEX keeps resisting revival efforts, but should be possible.
@larsbrinkhoff Agreed. USC ran it on their KL's, and TOPS 10 on the KA. When I was there they had like 7 different machines, I believe two of them were at the USC-ISI campus in Marina Del Rey. They had KA, KI, and KL variants to be sure.
@ChuckMcManis As far as I know, USC-ECL was the only KL10 on ARPANET running TENEX. And possibly anywhere. Most sites seem to have moved to TOPS-20, and USC did too after a while.