Four dubits (one byte) of d flip-flops (basil-flop design).

Magenta: decoder
Orange: data in
White: write
Light Blue: d flip-flops
Dark Green: output bussing

The address is a constant input.
The data in is a constant input.
The write is not a constant input.

The address controls which dubit to write the data to (writes once the write input is switched), and also what dubit to read (always visible).

The output holds the data as it was inputted, it does not swap the bits.