What you are calling the memory block is actually the Microprocessor.
I do not have the schematics but they should source the actual part
number used.
You will need an exact match to that part.
If you have a source of the schematics you should be able to locate the
processor number.
If you can find the part Roland should be able to install for you.
Also is your version the 12 bit or 14 bit DAC.
The 14 bit DAC have the DCB connection on the back and are known as
Jupiter 8a.
I'm not sure if they use the same processor again the schematics will
tell you that.
Dana
Hello,this is a little attachment to my previous email,I think I found
the
memory-block on the net...Is this the right one? follow the link
http://en.wikipedia.org/wiki/Zilog_Z80-Visit Dana's Synth Site
http://members.cox.net/synths