Frank,

Given Craigs findings re the external RAM, it might be worth using some assembler to perform a decent check on the RAM.

My understanding of the BASIC-52 routine which sizes/clears the RAM on startup is that it simply does a write/readback of a 0 to each byte. It stops when a non-zero is readback.

If all else fails, try buying V1.3 from Elektor. This fixes many of the bugs in V1.1 & adds support for higher clock rates.

Derek.