BIT - Z80 instruction reference

bitTest bit 
Tests one bit of a register or memory byte and sets Z when that bit is zero.
Used in 8-bit and 16-bit arithmetic, logic and bitsZ80 assembly
The screen, keyboard and mouse through portsZ80 assembly
Even or odd, count the set bits, multiply by shiftingZ80 assembly
Flappy birdZ80 assembly
 
SZHP/VNC ?●1?0–
● set from the result
0 always 0
1 always 1
? undefined afterwards
– not changed
Forms  bit ,    2 bytes · 8 cycles 
Tests bit b of r.
 bit ,    2 bytes · 12 cycles 
Tests bit b of (HL).
 bit ,    4 bytes · 20 cycles 
Tests bit b of the memory location pointed to by IX plus dd.
Operands b A bit number from 0 to 7, where bit 0 is the least significant bit. 
r An 8-bit register: a, b, c, d, e, h or l. 
(hl) The byte in memory at the address stored in hl. More
(ix+dd) The byte in memory at ix + dd, where dd is a signed displacement from -128 to 127, for example (ix+5) or (ix-3). (iy+dd) works the same way. More
         .org 0x8000
        ld b, 3
        bit 0, b
        halt