I have done this MANY times. I still have all the equipment although the brain is a little foggy. That was a LONG time ago. Try a byte swap as the image you are soft-kicking will not work as is when burned to a blank EPROM. A 27C400 should be fine for a 512k 3.1 image on a Rev 5 A500. A jumper might be required for the ROM to boot in that machine. Try looking up pins 1, and 31 if I recall correctly. Lastly when using a 256k image with a 512k EPROM you must repeat the image of the file to fill the last 256k of the EPROM chip. Any EPROM will not boot with an un-used empty section as I recall. Most likely you are fighting the "Big Endian <---> Little Endian" swap. Also burn it as Binary only, nothing else should be necessary. Look at the first few bytes in your buffer editor and you will see really quickly what's up. Also -DO NOT try this without a few blanks and an eraser on hand and be patient. Much trial and error may be required.'
Here is a tip. First simply copy your existing working ROM and see if your process works. Once you have this down, send me a PM for ideas about burning the coolest feature rich ROMs for all of my dusty Amiga's. I have PAID for just about EVERY LEGIT and legal Amiga OS ever released and I still posses them. This is why I don't find any trouble with burning my own.
