This is a drop in Kernal ROM replacement for the Commodore 64 Longboard variants (ASSY 326298*, KU-14194HB, 250407, 250425 and 250466). It can hold 4 Kernels that are selectable using the RESTORE key on the C64. Design is created by the RetroChannel.

Kernel:

1: 901227-03 standard commodore Kernel

2: JiffyDos, includes a valid license we buy  for the device.

3: JaffyDos, a slightlyb modified JiffyDos

4: EXOS V3.

Install

Remove the Kernal ROM at U4 on the C64 and insert this replacement, you may need to desolder the Kernal ROM and install a socket if it is not in one already. Connect a wire from the RSET pin on the Kernal ROM to the RESET line on the C64 mainboard. Likewise connect RSTR to the RESTORE line.

Finally connect the orignal power LED to the pins labelled LED+ LED- LED+, the orientation does not matter as they are the same when flipped. Note some C64s have a shorter LED cable that may not reach over to the Kernal ROM, in this case you will need to extend the wires, an easy way to do this is by using some male to female dupont connectors.

Usage

When you first power on the system you should notice the power LED flash rapidly for a second, if this does not happen double check your RESET and RESTORE wires are connected to the correct places on the C64 and that you have plugged the power LED into the Kernal ROM and not the original C64 LED connector.

On first boot you should be greeted with the 1st Kernal and everthing should look as normal. Holding the RESTORE key should cause the power LED to flash once every second or so, this is how we control the switcher and releasing the RESTORE key will "confirm" our selection.

1 flash: Resets the machine

2 flashes: Move to next Kernal

3 flashes: Jump to 1st Kernal

4 flashes: Jump to 2nd Kernal

5 flashes: Jump to 3rd Kernal

6 flashes: Jump to 4th Kernal

Here you find the data on how to install it (images).