I have been going through my Atari collection to see what still works. This 800XLF was known to be faulty, but not known to be a 800XLF, and was sitting in my garage until recently. I was therefore not surprised when it still refused to boot at all. I tried Shoestring's ROM/RAM tester blown into a 27C128 EPROM after socketing the Atari OS ROM and at least that gave me a frozen screen proving some main chips were working, but I was still doubting it could be the DRAM as it was Samsung manufacture