Z80
(Continued).
(C) WLODEK BLACK
00Bh. GROUP commands for the individual bits.
The group includes two types of commands for changing the
status of individual bits, and one subgroup of commands for the
analysis status bits.
SET - set the bit to 1;
RES - reset the bit to 0;
BIT - find out the status bits.
Addressing modes - A, B, C, D, E, H, L, (HL), (IX + nn), (IY +
nn). Full record team is made up of mnemonics, numbers of bits
and addresses of operands: SET 0, E
RES 7, (HL)
BIT 1, (IX +1).
SET command sets the appropriate bit to 1, the team RES -
resets to 0. The SET and RES do not affect the flagi.Primenenie
installation commands and reset bit is practiced in the
programming of external devices that are included as memory
cells, a procedure to correct the data, such as transcoding
lowercase capitalization, in the algorithms of calculations and
so on.
BIT Team enters inversion specified in the command bit in the
sign of zero-Z, after which he can be monitored by conditional
jump commands. Why is stored inversion bit, but not direct
value? Recall that set the zero flag Z = 1 indicates that the
true condition of p and e n a t c a zero. If the bit is 0, then
the flag will be put to 1, ie to create the conditions of
vanishing. Invert bit is introduced for programming convenience.
When we write "JR Z ,..." after "BIT ...", we mean the
vanishing of the scanned bit. Of course, it's convenient. BIT
Team also supports all of these addressing modes. In addition
to the flag Z, BIT command affects the flags of P / V and S,
but it impact is uncertain and can not be used.
BIT 2, L
BIT 0, (HL)
BIT 7, (IX +0).
[End of 7 th Text].
