Replacement of KERNAL ROMs

This page describes how to install a new EPROM as a replacement for your 24pin kernal ROM. The steps are similar for non-24pin components, except an adaptor is not required. You can use this guide to identify where the chip is in your C64/128.

Kernal replacements are needed when upgrading to JiffyDOS or Pwr-Load Kernals. Sometimes the 24pin chip is soldered into place. The safest way to get these out is by snipping the pins and soldering a socket into place. This is less risky than damaging the circuit board with too much heat.

Remember to work in a static free environment as electronic components can be damaged by static electricity.

Kernal EPROM Replacement:
Identification of 24pin Kernal ROM: - the ROM to be replaced normally has a part number such as 901227-xx where xx will be 01, 02 or 03
Removing the old ROM: - Using an IC extractor, or small flat bladed screwdriver, lever the chip from each end until it is removed. Be careful to not bend pins in the process.
Empty Socket: - Not much to say other than to check that the socket has not been damaged by your removal work.
Line-up the Adaptor Pins: - You will need to be careful that all pins of the adaptor are socketted and that none accidently fail to line-up. This is easiest done by aligning one row and then rocking the adaptor into place. Ensure that the adaptor and socket are orientated the same direction, pin for pin. The overhang should be to the end of the socket with a small notch in between the rows, usually to the rear of the circuit board.
Finishing it off: - Pushing the adaptor home should seat all pins. The lead with the toggle switch can be connected to the case by drilling a mounting hole and gluing into place.
The C64c doesn't need and adaptor: - this version of the C64 has a 28pin ROM with both the BASIC and KERNAL code. A ROM adaptor is not required, though one or more pins will need to be cut short or removed in a multi-ROM system.
The C128 and C128D: - this version has a separate 28pin ROM for the C64 and C128 kernals. A ROM adaptor is not required, though one or more pins will need to be cut short or removed in a multi-ROM system..
The C128DCR: - this version of the C128 has both Kernals in the same ROM chip.