Stefan Rueger

> It seems to me Arduino's implemenation of Optiboot does not support EEPROM. OK, optiboot has supported EEPROM from at least 2016, I think. The current version 8.3 certainly does....

@mcuee Thanks for unearthing AVR8X self-programming implementations (vvv useful) and for digging out other EEPROM related issues. None of these relate to _this particular_ issue (though Issue no 421 is...

> they probably should not use `-c arduino` Correct. Actually, no one should :) As you have seen #940 argues `-c arduino` is not a great match for bootloader needs....

OK, turns out that various bootloaders for which it is important to deal with EEPROM have solved this issue, particularly for those UPDI parts. Closing this issue

> Just wondering why you say that the bootloaders like optiboot_x and optiboot_dx have already solved the issue for the UPDI parts. Thanks. @mcuee I (perhaps mistakenly) thought that optiboot_x...

My proposal is to provide in `avr.c` generic `avr_read_byte_cache()` and `avr_write_byte_cache()` routines that, for programmers that have paged read/write functions, - Maintain a page-sized *flash* read/write cache for all *parts...

> by reading a flash page, modifying the content and writing it back again Exactly! With a r/w cache (for speed and lest wearing out memory unnecessarily) and using the...

> support other data than bytes Yes, I noted the addition of strings, etc. Vvv useful!

@mcuee Many thanks for testing! And for developing a good test bench. I am convinced that this will improve the quality of AVRDUDE over time (actually, it already has!), and...

Before starting on the flash write problem I checked a few edge cases of integer inputs for terminal write. I know from experience that parsing number strings in C is...