2. We must not overwrite bit 0-31 in 24/31 bit mode:
(PoP page 3-6)
Unless specifically stated to the contrary, the follow-
ing definition applies in this publication: whenever the
machine generates and provides to the program a
24-bit or 31-bit address, the address is made avail-
able (placed in storage or loaded into a general regis-
ter) by being imbedded in a 32-bit field, with the
leftmost eight bits or one bit in the field, respectively,
set to zeros. When the address is loaded into a gen-
eral register, bits 0-31 of the register remain
unchanged.