This is especially good if you've replaced the drive kernal ROM with something else and want to verify that the upgrade worked. You will receive back the drive DOS revision. From Star Commander, select F2 (User Menu), and choose user command and send a U9. A handy drive command for obtaining the drive DOS revision is U9.
The one I use supports the Motorola S19 format, a text-only format with checksums. I will not attempt to document how to burn an EPROM as each programmer is unique and the instructions vary greatly. To burn an EPROM requires an EPROM programmer. You can check them on the burner to see if they are indeed erased and if not, re-erase them for 1 minute increments, checking after each erasure session until they show erased. Typically EPROMs need about 3 minutes to erase. To erase an EPROM you will need a UV eraser.
I generally go with 200-250ns as they were very common. The Commodore chip specs for the 23 PROM's show them as slow as 450ns so almost any EPROM faster than 450ns will so. The speed of the EPROM is not so critical. See here for detailed instructions on how to build one. In order to upgrade to a newer ROM revision or change the ROM to something else and use either a 2732 (for the character set) or 2764 (for kernal/DOS) EPROM, a socket adapter must be built. The ROM's in the C64 and the original 1541 models are 24 pin and are not directly pin compatible with burnable 2732 or 2764 EPROMS.
