1. 1 College of Charleston, School of Science & Mathematics Dr. Anderson, Computer Science Department CS 250 Comp. Org. & Assembly CS 250 – Computer Organization & Assembly Instructor:Paul Anderson 212 JC Long andersonp@cs.cofc.edu Lecture slides, labs, and other materials courtesy of Dr. Michael Raymer, Wright State University, and Dr. Travis Doom, Wright State University, and Dr. Sridhar Ramachandran, Indiana University Southeast

2. 2 College of Charleston, School of Science & Mathematics Dr. Anderson, Computer Science Department CS 250 Comp. Org. & Assembly Why study computer organization? 1. You need to understand hardware to program well. –Cache thrashing –Concurrency –Representations 2. You need to understand hardware to program correctly. 3. You need to understand assembly language (at least every once in a while)

3. 3 College of Charleston, School of Science & Mathematics Dr. Anderson, Computer Science Department CS 250 Comp. Org. & Assembly Black Boxes l Every level of this hierarchy that you don’t understand is a black box –It might as well be magic –“Debugging by superstition” l The objective of this course is to move the black-box boundary down to the Microarchitecture level! Algorithm & Language The Problem ISA & Microarchitecture Circuits & Devices

4. 4 College of Charleston, School of Science & Mathematics Dr. Anderson, Computer Science Department CS 250 Comp. Org. & Assembly The instruction set architecture (ISA) l The next step is to translate the program into the instruction set of the particular computer that will be used to carry out the work of the program. l The Instruction Set Architecture (ISA) is the complete specification of the interface between programs that have been written and the underlying hardware that must carry out the work of those programs. –Examples: IA-32 (Intel, AMD, and others), PowerPC (Motorola) l Programs are translated from high languages in to the ISA of the computer on which they will be run by a program called a compiler (specific to the ISA). l Programs are translated from assembly to the ISA by an assembler Algorithm & Language The Problem ISA & Microarchitecture Circuits & Devices

5. 5 College of Charleston, School of Science & Mathematics Dr. Anderson, Computer Science Department CS 250 Comp. Org. & Assembly The microarchitecture l The next step is to transform the ISA into an implementation. The detailed organization of an implementation is called its microarchitecture. –The IA-32 has been implemented by several different processors over the past twenty years 8086 (Intel, 1979), 8286, 8386, 8486, Pentium, Pentium II, Athlon, Pentium III. –Each implementation is an opportunity for computer designers to make different trade-offs between cost and performance. [Computer design is always an exercise in trade-offs.] Algorithm & Language The Problem ISA & Microarchitecture Circuits & Devices

6. 6 College of Charleston, School of Science & Mathematics Dr. Anderson, Computer Science Department CS 250 Comp. Org. & Assembly The logic circuit l The next step is to implement each element of the microprocessor out of simple logic circuits. l Here there are also choices, as the logic designer decides how to best make the trade- offs between cost and performance. l Even in the case of addition, there are several choices of logic circuits to perform this operation and differing speeds and corresponding costs. Algorithm & Language The Problem ISA & Microarchitecture Circuits & Devices

7. 7 College of Charleston, School of Science & Mathematics Dr. Anderson, Computer Science Department CS 250 Comp. Org. & Assembly The devices l Finally, each basic logic circuit is implemented in accordance with the requirements of the particular device technology used. l So, CMOS circuits are different from NMOS circuits, which are different, in turn, from gallium arsenide circuits. Algorithm & Language The Problem ISA & Microarchitecture Circuits & Devices V in V out GND V cc RcRc RbRb

8. 8 College of Charleston, School of Science & Mathematics Dr. Anderson, Computer Science Department CS 250 Comp. Org. & Assembly CS Realities l You’ve got to understand binary encodings –Integers –Floats –Characters –Instructions l You’ve got to understand how a machine processes instructions –The stack l You have to understand memory –Memory references (pointers) l Computers do more than execute your program –I/O –Interrupts –Network behavior l In short: –You must understand the system in order to optimize performance!

9. 9 College of Charleston, School of Science & Mathematics Dr. Anderson, Computer Science Department CS 250 Comp. Org. & Assembly Understanding your hardware Intel® Core™ i7-3930K Processor (12M Cache, 3.20 GHz) # of Cores6 # of Threads12 Clock Speed3.2 GHz Max Turbo Frequency3.8 GHz Intel® Smart Cache12 MB Bus/Core Ratio57 Instruction Set64-bit Lithography32nm Recommended Customer Price$583 - $594 Idle StatesYes Enhanced Intel SpeedStep® TechnologyYes Execute Disable BitYes

10. 10 College of Charleston, School of Science & Mathematics Dr. Anderson, Computer Science Department CS 250 Comp. Org. & Assembly Where we are heading