My advice is to spend LOTS of hours on assembly language. The theoretical works seems to follow a pattern every year.....
RISC\CISC
Hex calculus (mostly add\sub)
Boolean algebra
Addressing modes
Bus architecture
Memory
Interrupts
Infix\postfix
etc.
Know exactly what the basic assembler instructions do:
MOV, AND, XOR, ADD, shift and rotate instructions, branching.....
If you struggle with boolean algebra like I do and you have multiple choice questions where you don't need to show each step, use a truth table to test each possible choice. this takes a lot longer, but if you have some spare time left in the exam it could mean 4 points without even knowing the boolean rules.