A part answering at one address that has been given no replies yet; a command takes
width bytes, two unless given.
Optionalwidth: number | nullThe address the part answers to.
Every write the part has received, oldest first: a command and any arguments after it.
How many transfers the part has served.
A part that is not there, answering commands with the replies it was given.
A write sends a command and any arguments after it; a read then takes the reply that command left, once, padded with
0xFFthe way an idle bus reads. A command given no reply leaves none, and a read then is not acknowledged, which is what a real part does when asked for data it does not have.