I managed to erase an EPROM (NM27C512Q) using sunlight. I left it outside for about a week, after that the chip was empty.

{{::nm27c512q.jpg?400|}}

Then I put XT-IDE BIOS onto it.

First, as the EPROM is 512 kbits (64 kBytes) and the [[3COM Etherlink III|3COM 3C509 network card]] has up to 32 kBytes support, I made a file that contains the BIOS 2 times.

{{::etherlink_with_eprom.jpg?400|}}

I wanted to write AT320INT.BIN (for Toshiba T3200SXC) to the EPROM.

In Linux, I made the file like this:
  # Create 64k file with 0xFFs (all 1s):
  dd if=/dev/zero ibs=1 count=65536 | LC_ALL=C tr "\000" "\377" > hexff.bin
  # Write BIOS to first half
  dd if=AT320INT.BIN of=hexff.bin conv=notrunc
  # Write BIOS to second half
  dd if=AT320INT.BIN of=hexff.bin bs=1 seek=32768 conv=notrunc
  # Rename file now that it contains the BIOS
  mv hexff.bin AT320NW.BIN

Then I wrote the BIOS (AT320NW.BIN) using XGEcu Pro programmer.

===== To do =====
  * https://www.imania.dk/samlesaet-hobbyelektronik-og-ic-er-relatively-universal-rom-programmer.htm