# Logic

Whilst its only recapped on in some of the lectures, it assumes knowledge from the engineering module, which the computer science Computer Organisation and Architecture (CS132) also covers.

A fair bit of this information is already in CS132 Logic Page. There are some engineering specific things, and stuff that's just handy to have on one page.

## Boolean Algebra Laws

There are several laws of boolean algebra which can be used to simplify logic expressions:

NameAND formOR form
Identity Law
Null Law
Idempotent Law
Inverse Law
Commutative Law
Associative Law
Distributive Law
Absorption Law
De Morgan's Law
• Can go from AND to OR form (and vice versa) by swapping AND for OR, and 0 for 1

Most are fairly intuitive, but some less so. The important ones to remember are:

## Latches

### SR Latch

• When is asserted, goes high.
• When is asserted, goes low.
• When both are de-asserted (low and low), holds its value
• When both are asserted (high and high), and goes low (not intended!)

### D latch

Passes through the input whenever is high, and hold when is low.

### D Flip Flop

Will copy the input to the output at rising edges of . Bit storage.