This adapter allows the use modern EPROMS as a replacement for the old Commodore Kernal. The original 2364 chips are ROM chips and there are no suitable programmable replacements. This adapter will allow the use of a 27C64, 27C128, 27C256 or 27C512 EPROM to replace the Kernal.

There are other options available but this one is easy to use and allows for more than one Kernal on the chip (27C128 and above) and easily select the desired Kernal via three jumpers.

When using a 27C256 chip for example, four different Kernals, such as the original or JiffyDOS or any other suitable Kernal image, provided it is not larger than 8KB, can be programmed into the chip. Using a 27C512, eight Kernals can be programmed.

The chips provided with the adapter are 27C512 and can be reprogrammed to your needs. I have added the original Kernal, a slightly modified version (different colour scheme and drive 8, rather than the tape drive, set as default), DolphinDOS 3 and EXOS V3 onto the chip. Because this is a 512kbit chip, all four Kernals are on the chip twice to ensure it is filled up. You can select the Kernal you want to use through a series of jumpers. If no jumpers are set, the original Kernal is selected.

Jumpers select the Kernals in reverse order of being programmed.

Here is a little table explaining the jumper settings:

When using a 27C256 chip, there is no need to use Jumper A15, when using a 27C128 chip, A14 is not needed and when using a 27C64, no jumper is required.

NOTE: This adapter is for C64 longboards (ASSY 250407, 250425 and 250466). It should also work with the original board but it has not been tested, so I cannot guarantee that it will work. The adapter is not suitable for the ASSY 250469 short boards! These use different chips, containing BASIC and the Kernal on one chip.

This is designed as a drop-in solution and if the Kernal chip of the motherboard is socketed, no soldering is required. Simply remove the old chip and insert the new one. If the original ROM is not socketed, you will have to de-solder it from the motherboard, install a socket and insert the replacement chip. I suggest you refrain from directly soldering the adapter into the motherboard as it will make later de-installation a lot more difficult.