Reads a value from a hardware port.
in a,(n) ;8-bit constant in a,(c) in b,(c) in c,(c) in d,(c) in e,(c) in h,(c) in l,(c) in (c) ;undocumented command
This command alters no flags.
N flag reset, P/V represents parity, C flag preserved, all other flags affected by definition.
This command, along with OUT, is used for hardware interfacing.
The undocumented command IN (C) reads from the port and affects flags, but does not store the value to a register.
r denotes 8-bit register.