CS251 - Computer Organization and Design - Spring 2008

Lecture 38 - Review for Final Exam

Practical Details

1. Assignment 9
2. Optional Assignment
3. addresses.pdf, virtual.pdf, microcode.pdf

Topics

Combinational Logic

Big Ideas

1. Digital versus analogue
   • error control
2. AND, OR, NOT, etc.
3. More complex components

Skills

1. Manipulate truth tables
2. Simplify Boolean expressions
3. Manipulate disjunctive normal forms
4. Create circuits from truth tables or Boolean expressions

Sequential Logic

Big Ideas

1. Latch, flip-flop
   • component that retains state
2. Three-state outputs
3. Clock
4. Finite state machines

Skills

1. Create simple sequential circuits
   • counters
   • memories
2. Build simple state machines

Data Representation & Manipulation

Big Ideas

1. Numbers
   • two's complement
   • floating point
2. ALUs
   • addition
   • multiplication

Skills

1. Manipulate numbers in different representations
2. Construct one-bit ALU
   • compound it into wider ALU

Single-cycle Processors

Big Ideas

1. Categories of instructions
   • keep it simple
2. Datapaths
   • multiplexed, using multiplexers
3. Control

Skills

1. Map instructions onto data paths
2. Map instructions onto control logic
3. Calculate things like the fastest possible clock

Multi-cycle Processors

Big Ideas

1. Phases of instruction execution
   • multiple phases per instruction
   • variable number of phases per instruction
   • multiple datapath configurations per instruction
   • one clock per phase
2. Reuse of hardware
3. Sequence of control states
   • for each instruction
   • microcode

Skills

1. Separate a single cycle design into phases
   • datapaths
2. Design sequential control logic
   • finite state machine

Pipelining

Big Ideas

1. Overlap phases of instruction execution
2. Preserving state/control using registers
3. Hazards
   • structural
   • control
   • data

Skills

1. Introducing registers to preserve state
2. Identifying and resolving hazards, using
   • hardware replication
   • stall
   • branch prediction
   • forwarding
3. High-level view of adding hardware to enable branch prediction and forwarding

Memory Hierarchies

Big Ideas

1. Levels of access
   • bigger & slower as they get further from the processor
   • hits, misses
2. Dividing the address
   • address space
   • blocks of memory
3. Cache
   • line = block
   • direct-mapped, associative, set associative
   • line replacement
4. Virtual memory
   • swapping, protection
   • page = block
   • translation-lookaside buffer (TLB)
   • page replacement
   • role of software

Skills

1. Map an address onto a cache line or a physical address
2. Iteratively access slower and bigger memories
3. Create a cache with given parameters

Input/Output

Big Ideas

1. How a bus works
   • bus arbitration
   • master/slave
   • bus transaction
   • handshake
2. Characteristics of disk drives
3. Multi-level buses

Skills

1. Calculate the speed and bandwidth of buses and peripherals

Return to:

• Bill Cowan's lecture notes for CS251 in W08
• Bill Cowan's Winter 2008 CS251 page
• Bill Cowan's CS251 page
• Bill Cowan's teaching page
• Bill Cowan's home page