Apple IIc ROM0, ROM3, ROM4x
8.00USD

In ROM4x, Enable Smart Port and add self-diagnosis function and more.
Ideal for upgrading from ROM255.
To replace the ROM, in addition to replacing it, you will also need to change the solder jumpers in two places (W1 and W2). This is to enable the A14 address.*Requires a soldering iron and a utility knife.
Detailed instructions on how to replace the ROM can be found here.