> the same process works to modify the edid stored on a typical monitor
That would be a strange oversight by the hardware developers.
Typically they would buy pre-programmed EPPROMs and then place it on to a board where the write enable pin is never pulled high.
It would be strange to put an EEPROM into a product like a monitor and leave it writable, but I’ve seen stranger things on shipping hardware.
Modern monitors don't even use an EEPROM chip for EDID anymore. The I2C bus is hooked up to a microcontroller inside the monitor, which allows it to implement Display Data Channel. This way you can tune things like display brightness and color profile from an application running on the computer, instead of messing around with the monitor's OSD.
Tools like ddcutil aren't very well-known, but they can be quite useful if you want to do something like DIYing a KVM switch by just having the PC tell the monitor to switch to a different input!
> DIYing a KVM switch by just having the PC tell the monitor to switch to a different input!
I made a tiny contribution to the ddcutil-db database when I did exactly that. My monitor wasn't supported initially, but it wasn't hard to use the utils and templates to poke around and find the correct addresses for basic settings and input switching.
It was a nice afternoon's work to get it all working.
Do any monitors use the I2C multi-peripheral feature to allow both DDC communication and an I2C EEPROM to exist at different addresses on the same bus? Or is it cheaper to integrate functionality into a controller chip? (Though DP tunnels EDID over the aux bus, and (I assume) doesn't use an EEPROM to begin with.)
Yeah,it shouldn't happen - but I've seen it happen. What's worse, the first batch we got from that place weren't flashed with an EDID at all - and were shipped directly to customers (who mostly didn't notice, because the main product it connected to had default that worked, but it wasn't optimal. Meant none of those screens could be used with a normal laptop though). Ironically the combination of the two issues meant we could have fixed the EDID in the field, but we didn't dare in case we bricked someone's $x000 TV.