Probably have to use old school assembly and/or simple C, I remember ZX Spectrum ROM...
Regarding UART boot, it might be possible to do only UART speed init in OTP Boot, then jump in Boot ROM (skipping it's init).
Another (crazy) way would be to drive a slower external clock as BootROM expects 12MHz, still easier than to program the bloody OTP.
@Tharre: OTP Image needs to start with a vector table as usual?
Regarding UART boot, it might be possible to do only UART speed init in OTP Boot, then jump in Boot ROM (skipping it's init).
Another (crazy) way would be to drive a slower external clock as BootROM expects 12MHz, still easier than to program the bloody OTP.
@Tharre: OTP Image needs to start with a vector table as usual?
Statistics: Posted by gmx — Sun Jul 06, 2025 12:40 pm