EEE 435 Principles of Operating Systems

1. EEE 435Principles of Operating Systems Computer Hardware Pt I (Modern Operating Systems 1.4)

2. Quick Review • What are the two main “views” of an operating system? • Name some of the types of operating systems Dr Alain Beaulieu

3. Outline • Computer Components Overview • Processors • Part of a processor • Processor types • Modes of Operation • Types of Memory Dr Alain Beaulieu

4. Components Overview • An operating system is intimately tied to the hardware on which it operates Monitor Bus Dr Alain Beaulieu

5. Processors • Brain of the computer • CPU Functions: • Fetch an instruction from memory • Decode the instruction an operands • Execute the instruction • Repeat • More complicated in practice... Dr Alain Beaulieu

6. Processors (parts) • The “core” of a CPU is the ALU • Other resources inside the CPU: • Generic registers • Used to hold variables during work • Program counter • Points to the next instruction Dr Alain Beaulieu

7. Processors (parts) • Other resources inside the CPU: • Stack pointer • Points to the top of the stack of the current process • Program Status Word (PSW) • Contains condition code information Dr Alain Beaulieu

8. Processors (types) • Once an instruction is in the pipe it comes out, even if it has to be ignored! A Pipeline CPU MOVEQ #5, R1 MOVEQ #0, R2 LOOP ADDI #1,R2 CMP R1, R2 BNE LOOP . . . Dr Alain Beaulieu

9. Processors (types) • Multiple execution units • Multiple instructions fetched • Hardware largely puts them back in order • Both models expose OS designers to the underlying architecture/complexity!!! A Superscalar CPU Dr Alain Beaulieu

10. Processors (modes) • Two modes: • Kernel • Every instruction available • OS runs in this mode • Program can enter this mode to have an instruction processed by using a trap • User • Programs only usually “see” a restricted area of memory • Only a subset allowed for access • Usually I/O and memory functions forbidden Dr Alain Beaulieu

11. Memory • Ideal memory: • Extremely fast (faster than CPU execution time) • Large • Cheap • Can we do that with today’s technology? • NO! Dr Alain Beaulieu

12. Memory Types (and Hierarchy) • Multiple memory types give balance of speed, size and cost but... • ...add to complexity A Memory Hierarchy Dr Alain Beaulieu

13. Memory Types • Registers • Are embedded into the CPU and are typically just as fast • Registers are managed by the program (even if the compiler made the final decisions) Dr Alain Beaulieu

14. Memory Types • Cache • Very fast but expensive memory • Potentially many “levels” of cache • Lives “near” CPU • Usually hardware controlled Dr Alain Beaulieu

15. Memory Types • Main Memory (RAM) • The “workhorse” • Still growing rapidly Dr Alain Beaulieu

16. Memory Types • Magnetic Disk • Two orders of magnitude cheaper • Three orders of magnitude slower Dr Alain Beaulieu

17. Memory Types • Magnetic Tape • Used for backup storage/large data sets • Since usually in storage, it must be loaded into a reader before access (human or robot performed) • Very slow but exceedingly cheap! Fred, the tape guy. He hates his job. Dr Alain Beaulieu

18. Other kinds of computers to radar and other ADATS TEU TAU LEU SEU ECU MV PS CMP Interface Elec Unit Mount Servo Elect Unit Discrete I/O 24/24 Bits CEU Serial Interface & Auto Scanner Clock and interrupts 16 channel DPU R/D Converter 16 Channels A/D Converter 16 Channels D/A Converter 24 Channels Main Memory Resolvers GBA, LOSSA Analog I/P GBA, LOSSA Analog O/P SEU Dr Alain Beaulieu

19. Other kinds of computers Dr Alain Beaulieu

20. Quiz Time! Questions? Dr Alain Beaulieu