The SDD syllabus is the bible, its what the HSC examiners must use. According to this bible you need to know about:
Specialty circuits, including:
-half adder
-full adder
-flip-flops as memory store
So its not really very detailed, so I can only give my opinions. Some teachers feel I went mental with this stuff in my text, obviously I disagree.
Here's what I'd learn/know about adders:
-Be able to draw a half-adder without even thinking.
-Be able to turn your half-adder design into a full adder without even thinking.
-Be able to explain how and what both the half and full adder do.
-Be able to explain how full adders can be linked to add multiple bit numbers.
And for flip-flops:
-Know about one flip-flop design in detail
-Be able to draw the thing
-Explain how it works
-Create a truth table for it
-Explain how it stores a bit
-Know about other flip-flop designs in terms of what they can and can't do
HTH
Sam