Replacing the CPU


The standard CPU for the Sun3-Series is the MC68020. This chip can be replaced by the MC68030 CPU. You'll have to solder a socket into the empty space lefto to the MC68020. After this just remove the 68020 and the system will work as before.


The Socket ID is U111. The empty solder-field to the left is an empty 68030 socket. In the middle you can see the CPU (MC68020-20) and to the right is the FPU (MC68881-20).


There's no speed improvement because the 68030 isn't faster than the 68020. The MMU is disabled because the CPU-Board implements the standard Sun3 MMU with 8 Contexts. The Data-Cache of the 68030 isn't used. The only adventage of usen the 68030 is it beeing available at higher clock speeds. I use a 50MHz version in my system and at the moment I'm testing a clock-doubling hardware.
The clock-doubler has past it's first board-revision and my machine is still alive. I found some bug's and when I find some time again I'll make a new Version. The Board is evolving but very slow ;)