Κεφάλαιο 1 Αφαιρετικότητα και Τεχνολογία Υπολογιστών (Computer Abstractions and Technology) 1
Υπολογιστές Computers are basically used in three different classes of applications: Desktop computers: designed for use by an individual, usually incorporating a graphics display, keyboard, and mouse Servers (Εξυπηρετητές): used for running larger programs for multiple users often simultaneously and typically accessed only remotely (via a network) Embedded computers (Ενσωματωμένοι υπολογιστές): placed inside another device used for running one predetermined application or collection of software 2
Υπολογιστές: Desktops Known as Personal Computers Deliver good performance to a single user at low cost Desktop computing is one of the largest computer markets nowadays, even though they ve only been around for the last 30 years! 3
Υπολογιστές: Servers Carry large workloads Single complex applications (e.g. scientific computing or engineering application) or many small jobs (e.g. web server) Span the widest range of cost and capability Supercomputers 4
Υπολογιστές: Embedded Computers Span the widest range of applications and performance Most users never really know there s a computer in their devices YOU own at LEAST one of these 5
Υπολογιστές (συν.) # of processors in embedded devices is growing 40% annually # processors in desktops and servers growth is similar, around 9% annually Number of distinct processors sold between 1998 and 2002 6
Από τι αποτελείται ένας Υπολογιστής? Typical Components (not all apply to embedded computers): input (mouse, keyboard) output (display, printer) memory (disk drives, DRAM, SRAM, CD) network processor (datapath and control) ** Our focus ** Implemented using millions of transistors Impossible to understand by looking at each transistor We need... 7
Αφαιρετικότητα (Abstraction) An abstraction omits unneeded detail, helps us cope with large complexity Hardware and Software consist of hierarchical levels, lower level has more details Thus, higher level model is simpler details are abstracted Hardware in a computer can only execute very simple low-level instructions (machine language) High-level language program (in C) Assembly language program (for MIPS) Γλώσσα Υψηλού Επιπέδου Μεταγλωττιστής Συμβολική Γλώσσα Συμβολομεταφραστής swap(int v[], int k) {int temp; temp = v[k]; v[k] = v[k+1]; v[k+1] = temp; } swap: Compiler muli $2, $5,4 add $2, $4,$2 lw $15, 0($2) lw $16, 4($2) sw $16, 0($2) sw $15, 4($2) jr $31 Assembler Which of the terms on the right are abstractions? Which one is the higher level and which the lower? Binary machine language program (for MIPS) Γλώσσα Μηχανής 00000000101000010000000000011000 00000000000110000001100000100001 10001100011000100000000000000000 10001100111100100000000000000100 10101100111100100000000000000000 10101100011000100000000000000100 00000011111000000000000000001000 8
Πως λειτουργούν οι Η/Υ? Τι υπάρχει κάτω από το πρόγραμμα / λογισμικό σου? Need to understand all of the following abstractions: Applications software Systems software (O/S, Compilers) Assembly Language Machine Language Architectural Issues: i.e., Caches, Virtual Memory, Pipelining Sequential logic, finite state machines Combinational logic, arithmetic circuits Boolean logic, 1s and 0s Transistors used to build logic gates (CMOS) Semiconductors/Silicon used to build transistors Properties of atoms, electrons, and quantum dynamics Higher level abstraction Lower level abstraction 9
Ορισμένοι Απαραίτητοι Ορισμοί Application Software: provides interaction between the user and the System software, ex.: High-level programming language: a portable language (C, Fortran, etc) composed of words and algebraic notation. Web browser, word-processing software, etc System Software: provides services that are commonly useful, such as: Operating System (Λειτουργικό Σύστημα): supervising program that manages the resources of a computer for the benefit of the programs that run on the machine Compiler: translates high-level language statements (ex. C, Java) into assembly language statements Assembler: translates symbolic statements/instructions (ex. Assembly) into machine language (binary) 10
Ιεραρχία Λογισμικού/Υλικού (άλλο διάγραμμα) Each level can have its own internal hierarchy. For example: System Software Compiler Assembler 11
Instruction Set Architecture (ISA) (Αρχιτεκτονική Συνόλου Εντολών) A very important abstraction also referred as simply architecture of the computer interface between hardware and low-level software (machine language) the abstract structure of a computer that a machine language programmer must know to write programs standardizes instructions, machine language bit patterns, etc. advantage: different implementations of the same architecture (family of processors=same architecture, different processors). For example, 80386, 80486, Alpha 21064, 21164, 21264, 12
Instruction Set Architecture (ISA) (συν.) ISA is NOT compatible between processors from different families Some modern ΙSAs: IA-32, PowerPC, MIPS, SPARC, ARM High-level programming language Compiler Assembly language Assembler Machine language Hardware ISA: interface of machine language with hardware 13
Βασική δομή Υλικού του Η/Υ The 5 classic components: Processor/CPU (Επεξεργαστής) Control (Μονάδα Ελέγχου): Part of CPU managing the operation/interaction between datapath, memory, and I/O Datapath (Διάδρομος Δεδομένων): Component of CPU that performs arithmetic operations Memory (Κυρίως Μνήμη): Storage area in which programs are kept when running, contains instructions and data Peripherals (Περιφερειακές Μονάδες) Input (Εισόδου): device used to supply the computer with input information Output (Εξόδου) : device used to convey the results of computation to the user or another computer 14
Βασική δομή Υλικού του Η/Υ Observe that this organization is independent of hardware technology. Also, fits all common computer architectures 15
Τι έχει μέσα το κουτί? power supply (τροφοδοσία) Processor (under the heat sink) DVD drive fan with cover zip drive hard drive motherboard (κυρίως πλακέτα) processor memory I/O interface 16
Μια πιο κοντινή ματιά στον επεξεργαστή Miscellaneous Interface Logic Microphotograph of Pentium 4 processor chip Major functional blocks of the Pentium 4 processor chip 17
Μικροφωτογραφίες άλλων επεξεργαστών Pentium UltraSparc 18
Μνήμη του Υπολογιστή Registers (Καταχωρητές) On-chip storage, part of architecture Cache (Κρυφή Μνήμη) Small, fast memory that acts as a buffer for a slower, larger memory Hierarchical: 1 st level, 2 nd level, Main Memory (Κυρίως Μνήμη ή απλά Μνήμη) Holds programs while they are running. Usually DRAM chips Secondary Memory (Δευτερεύουσα Μνήμη) Hard disk, Floppy, CD, Zip, FLASH 19
Ταξινομήσεις Μνήμης Duration (Βάση διάρκειας) Volatile (Πρόσκαιρη) Retains data only if it receives power, i.e. once off power data is lost, running program storage Non-Volatile (Μόνιμη) Retains data even in the absence of power, long-term storage Technology (Βάση τεχνολογίας) CMOS (ROM, RAM, SRAM, DRAM, FLASH) Static RAM expensive, fast, used for registers Dynamic RAM used for main memory Magnetic Disk (hard disk, floppy, zip) Laser/Optical (CD, DVD) Volatile Non-volatile 20
Τεχνολογίες Επεξεργαστών και Μνήμης Year Technology Used 1951 Vacuum Tube (Ηλεκτρονική Λυχνία) Relative Performance Unit Cost 1965 Transistor 35 1975 Integrated Circuit (IC) (Ολοκληρωμένο Κύκλωμα) 1 900 1995 Very Large Scale Integration (VLSI) 2,400,000 2005 Ultra Large Scale Integration (ULSI) 6,200,000,000 21
O «νόμος» του Gordon Moore Νόμος του Moore (1965): «Ο αριθμός των τρανζίστορ ανά τετραγωνική ίντσα διπλασιάζεται κάθε 18 μήνες» 22
O «νόμος» του Gordon Moore (συν.) Νόμος του Moore (1965): «Ο αριθμός των τρανζίστορ ανά τετραγωνική ίντσα διπλασιάζεται κάθε 18 μήνες» Growth of capacity per DRAM chip 23
Πρόοδος της Τεχνολογίας Η/Υ Performance (Απόδοση) 1971: 1 million instructions/sec 2001: 1 billion instructions/sec Storage (Χωρητικότητα) 1971: 10MB 2001: 80,000MB Cost (Κόστος) 1971: $4,000,000 2001: $2,000 Performance/Size/Cost improvement factor is ~8 billion (in 30 years!) 24
Πρόοδος της Τεχνολογίας Η/Υ Another way to look at it 25
Η κατασκευή ολοκληρωμένων σήμερα It all starts from Silicon (Πυρίτιο): natural element which is a semiconductor Semiconductor (Ημιαγωγός): a substance that does not conduct electricity well. Can be transformed, via special chemical process, into any of the below: Excellent electricity conductor Excellent electricity insulator Alternate the above under special conditions == switch Transistor: silicon-based semiconductor that acts as a switch VLSI chip: composed of millions of combinations of transistors, conductors and insulators 26
Η διαδικασία κατασκευής Typical thickness: 0.1 inch 27
Yield The percentage of good dies (=chips) from the total number of dies on the wafer Yield = 1 / ( 1 + ( Defects per area x Die area/2 ) ) 2 28
Ιστορική Αναδρομή 1946 -- ENIAC (=Electronic Numerical Integrator and Calculator) built in World War II was the first general purpose computer Used for computing artillery firing tables 80 feet long by 8.5 feet high and several feet wide Each of the twenty 10 digit registers was 2 feet long Used 18,000 vacuum tubes Performed 1900 additions per second 29
Ιστορική Αναδρομή (συν.) 1951 -- UNIVAC I (Universal Automatic Computer): First popular commercial development Cost: around $1 million, 48 were sold! 30
Ιστορική Αναδρομή (συν.) 1964 IBM System/360: First move into the idea of architecture abstraction first computer family Six implementations, varied in price and performance by a factor of 25 IBM/360-40: 1.6 MHz, 32-256 KB, $225,000 IBM/360-65: 5.0 MHz, 256 KB 1 MB, $1,200,000 IBM/360-50: 2.0 MHz, 128-256 KB, $550,000 IBM/360-75: 5.1 MHz, 256 KB 1 MB, $1,900,000 31
Ιστορική Αναδρομή (συν.) 1965 PDP-8 by Digital Equipment Corporation (DEC): The first minicomputer! Cost: under $20,000 1971 Intel invents the first microprocessor, the Intel 4004 1977 Steve Jobs and Steve Wozniak introduce the Apple II personal computer 1981 IBM announces their first personal computer IBM-PC (Intel processor) The best-selling computer of all kinds! IBM-compatible from here on Xerox Alto: primary inspiration for modern desktop computer 32
Ιστορική Αναδρομή (συν.) The Apple II Plus The Xerox Alto 33
Ιστορική Αναδρομή (συν.) 1976 Gray -1 : the first supercomputer (successor of Gray, 1963) At that point, the fastest in the world, the most expensive, and the computer with the best cost/performance for scientific computing 34
Ιστορική Αναδρομή (συν.) Χρόνος Όνομα Μέγεθος (ft 2 ) Ισχύς (watts) Απόδοση (adds/sec) Μνήμη (KB) Κόστος $ Απόδοση/ Κόστος Vs Univac Κόστος (2003$, με πληθωρισμό) Απόδοση/ Κόστος Έναντι Univac 1951 Univac1 1000 124,500 1,900 48 1,000,000 1 6,107,600 1 1964 IBM S360/ Mode50 60 10,000 500,000 64 1,000,000 263 4,792,300 318 1965 PDP 8 8 500 330,000 4 16,000 10,855 75,390 13,135 1976 Cray -1 58 60,000 166,000,000 32,768 4,000,000 21,842 10,756,800 51,604 1981 IBM PC 1 150 240,000 256 3,000 42,105 5,461 154,673 1991 HP900/ model 750 1996 ΙIntel PPro PC (200 MHz) 2003 Intel Pentium 4 PC (3.0 GHz) 2 500 50,000,000 16,384 7,4000 3,556,188 9,401 16,122,356 2 500 400,000,000 16,384 4,400 47,846,890 4,945 239,078,908 2 500 6,000,000,000 262,144 1,600 1,875,000,000 1,600 11,452,000,000 Χαρακτηριστικά βασικών εμπορικών υπολογιστών από το 1950 35