This is the KERNAL ROM for the Commodore VIC-20. When this chip fails, most of the time you’ll see a black screen on power up. These chips were pulls from scrap VIC-20 boards, but they have been tested in a working VIC-20 board.
Note about stock: I have limited stock ready to ship, but I have more that can be tested. So if you see that it is out-of-stock, just wait a few days and check back as I will likely have more.