RAM16K

[Zorro]

Why the Hack has 16K RAM instead of 32K? To make sure, we are not falling asleep, during copy&paste...

[WBahn]

No, it's because of the memory mapped I/O.

The SCREEN output memory conveniently occupies exactly 8K.

But the KEYBOARD occupies just a single word. Carving out a single word for mapped input isn't terribly clean, so they effectively allocated the entire remaining 8K of address space to mapped input with there only being a single word that is actually populated.