Ok I tried your suggestions. I removed the user memory card from the slot and just checked what that would do..

but still got as far as the point descibed above …then I rebooted and held down the “8” key

and it worked ..this brought up the “welcome to the DSP 4500” menu page and then access to all menus from there.

I wonder could the bad battery in the memory card cause this “back checksum” error message in the interanl RAM?

by clearing all” what does that do for the “bad checksum” or “Internal RAM” problem given in the error message?

Are you saying there is a battery for the Internal RAM also that lasts 8 /10 years?

if they are hard to find…where might I find one as a back up ?

I’ll let you know if something else happens in th next few days..

Thanks very much for your help!

J Bell