Provides a buffered bus that decodes the address lines and inhibits the internal 1K RAM (and external 16K RAM) when I/O is selected. Up to 8 byte-wide ports. Connects to the ZX-81 via a custom cable.
I/O Expansion Port

Provides a buffered bus that decodes the address lines and inhibits the internal 1K RAM (and external 16K RAM) when I/O is selected. Up to 8 byte-wide ports. Connects to the ZX-81 via a custom cable.
