Addressing mode

Bit 31 in PSW is called extended addressing mode bit. Bit 32 is called basic addressing mode bit. 

When both bits are zero, it uses 24 bit addressing. When bit 32 is a one, it uses 31 bit addressing. When both bits are ones, it uses 64 bit addressing. 

Address related to cross memory operation is always 31 bits. 

Address in CCW is either 24 or 31 bits