Hi,

I am experimanting with a HEF4021 IC to read some keys. According to the
data sheet, the 4021 is a 8-bit Parallel-in-serial-out register.
I know it is possible to read out the 8 bits with only 3 IOpins (2 outputs,
1 input).
Example: RB1: LOAD              Output
          RB2:  CLOCK           Output
          RB3: Data             Input

How do I do this? What do I do with the Ds pin (pin 11)?
This is what I already tried:
Make PL (parallel load) low--> high
wait
PL from H-->L.
generate CLOCK pulse.
Read input (from WHAT pin?? I tried them all...)
generate next clock pulse.
etc.

What did I do wrong?