Цитата Сообщение от cyb2600 Посмотреть сообщение
it doesn't respond to the resets.
That could be a clue, actually.
Does the CPU gets a proper RST signal? What happens on the address bus right after that? Do the address lines of the bootloader ROM chip get the same signals that are on the address bus?

Another place to look is whether video memory refresh works properly (as far as I recall it uses its own EEPROM to form all the right signals)

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Цитата Сообщение от cyb2600 Посмотреть сообщение
Should they go high again after the boot ROM is copied to RAM?
The ROM is not copied to RAM (apologies for probably misleading you with an inappropriate use of the word "shadowing").
It's rather like chip select (inverted, I assume) goes low for ROM and high for RAM when the CPU is reading data and vice versa when CPU is writing data.