Is this for a Raspberry Pi? My RPi::WiringPi handles this shift register if on a Pi. See that linked documentation and associated FAQ for full details:

use RPi::WiringPi;
use RPi::Const qw(:all);
 
my $pi = RPi::WiringPi->new;

my ($base, $num_pins, $data, $clk, $latch)
  = (100, 8, 5, 6, 13);
 
$pi->shift_register(
    $base, $num_pins, $data, $clk, $latch
);
 
# now we can access the new 8 pins of the
# register commencing at new pin 100-107
 
for (100..107){
    my $pin = $pi->pin($_);
    $pin->write(HIGH);
}
[download]

Update: Whoops, I misread the IC device number. My code is for a 74HC595 (output) not a 74HC165 (input). Sorry for the noise.

Thanks, will check module tomorrow and let you know how things are. Now I know where to start. I ordered PCB and 74HC165, expect to get it on few days. Will try real example at that time. Thanks Robert

How is this IC connected to the system? If you're working on a Raspberry Pi, you might want to look at stevieb's RPi:: series of modules, which includes RPi::SPI, RPi::Serial, and RPi::WiringPi.

Update: Fixed missing links.

Thanks haukex, unfortunately after I posted I realized that the IC in question here is parallel input, where I have only got code for the parallel output register.

I'll put this chip on my list now though.