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
|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.