Von Newman Architecture (1/3) COMP9032: Microprocessors and Interfacing Memory (Program and Data) Introduction to Microprocessors Control Unit Arithmetic and Logic Unit http://www.cse.unsw.edu.au/~cs9032 Lecturer: Hui Wu Session 2, 2008 Input Output John von Neumann in the 1940s 1 2 Von Newman Architecture (3/3) Von Newman Architecture (2/3) EDVAC, one • Memory of the first • Input electronic § Stores both program and data stored program computers § Gets the input ( data and program) from users • Control unit • Output § Directs the operations of the other units by § Sends the output to users providing timing and control signals. • ALU and control unit are collectively called CPU • ALU (Central Processing Unit) § Performs arithmetic and logical operations such as addition, subtraction, multiplication and division. 3 4
Harvard Architecture (1/2) Harvard Architecture (2/2) • Program and data are stored in separate memories, Memory (Program) Memory (Data) allowing accessing program and data at the same time. • AVR microcontrollers use Harvard architecture. Control Unit Arithmetic and Logic Unit Input Output 5 6 Computer Bus Bus-Oriented Computer Architecture • A bus is a set of parallel conductors that transfer data between different components of a computer. … CPU Memory I/O Device 1 I/O Device n • A bus has three main parts: Data Bus § Data bus Address Bus v Carries data § Address bus Control Bus v Carries the address of data § Control bus v Carries control signals 7 8
Microprocessors Intel’s Microprocessors (1/3) Name Date Transistors Microns Clock Data width MIPS speed • A microprocessor is a CPU on a single 8080 1974 6,000 6 2 MHz 8 bits 0.64 Integrated Circuit (IC). 8088 1979 29,000 3 5 MHz 16 bits, 8 bit bus 0.33 80286 1982 134,000 1.5 6 MHz 16 bits 1 • A microprocessor can manipulate 80386 1985 275,000 1.5 26 MHz 32 bits 5 numbers of a fixed width only. The first microprocessor 80486 1989 1,200,000 1 25 MHz 32 bits 20 Intel’s 4004 was introduced in 1971 § For example, a 8-bit microprocessor can do Pentium 1993 3,100,000 0.8 60 MHz 32 bits, 64 bit bus 100 addition and subtraction of two 8-bit numbers at a Pentium I 1997 7,500,000 0.35 233 MHz 32 bits, 64 bit bus 300 time. Pentium II 1999 9,500,000 0.25 450 MHz 32 bits, 64 bit bus ~510 Pentium 4 2000 42,000,000 0.18 1.5 GHz 32 bits, 64 bit bus ~1,700 Pentium 4 2004 125,000,000 0.09 3.6 GHz 32 bits, 64 bit bus ~7,000 “Prescott” 9 10 Intel’s Microprocessors (3/3) Intel’s Microprocessors (2/3) • Clock speed is the maximum rate that the chip • The date is the year that the processor was can be clocked at. first introduced. • Data Width is the width of the ALU. For • Transistors is the number of transistors on the example, an 8-bit ALU can do the addition, chip. subtraction and multiplication of two 8-bit The Intel 8080 was the numbers, while a 32-bit ALU can manipulate • Microns is the width, in microns, of the first microprocessor in 32-bit numbers. smallest wire on the chip. For comparison, a Intel Pentium 4 a home computer processor human hair is 100 microns thick. As the feature • MIPS stands for "millions of instructions per size on the chip goes down, the number of second" and is a rough measure of the transistors rises. performance of a CPU. 11 12
Microcontrollers Embedded Systems • A microcontroller (also MCU or µC) is a • An embedded system is a special-purpose computer-on-a-chip. computer system designed to perform one or a few dedicated functions. It is usually • In addition to the usual arithmetic and logic embedded as part of a complete device elements of a general purpose microprocessor, including hardware and mechanical parts. the microcontroller typically integrates additional elements such as read-write memory • Examples: Microprocessors and for data storage, read-only memory, such as Network router, an microcontrollers are • Consumer electronics: Personal digital example of an everywhere in our flash for code storage, EEPROM for permanent assistants (PDAs), mp3 players, mobile phones, embedded system . daily life data storage, peripheral devices, and videogame consoles, digital cameras and DVD Labelled parts include a microprocessor (4), players. input/output interfaces. RAM (6), and flash • Transportation systems: Inertial guidance memory (7). • Microcontrollers are frequently used in systems, GPS receivers, anti-lock braking embedded systems such as automobile engine system (ABS), Electronic Stability Control Atmel AVR ATmega8 control systems, remote controls and office (ESC/ESP) and automatic four-wheel drive. 13 14 machines. Computer Memory Hierarchy Registers Decreasing • A small amount of storage on the CPU whose contents can speed and Increasing be accessed more quickly than other storages available cost Processor size elsewhere. Auxiliary • Most, but not all, microprocessors operate on the principle storage of moving data from main memory into registers, operating Off-chip (hard disk, memory on them, then moving the result back into main memory—a floppy (RAM, so-called load-store architecture. disk, ROM) CDROM) • On a microprocessor of n-bits, each register can store n-bit data. For example, on an 8-bit microprocessor each register Cache or can can store 8 bit data. Registers Main Slowest On-chip memory and Fastest but memory • The number of registers on a microprocessor is small. most (SRAM) cheapest 15 16 expensive
Cache Memory RAM • A type of computer memory that can be accessed • A high speed memory located on CPU or next to CPU that randomly; that is, any byte of memory can be accessed is managed by hardware. without touching the preceding bytes. • CPU uses cache memory as a high speed buffer to temporarily store data and instructions. • Two types: DRAM (Dynamic Random Access Memory) and SRAM (Static Random Access Memory). • Data and instructions are loaded into cache memory by its associated hardware without software’s help. § The two types differ in the technology they use to hold data. • When accessing data and instructions, CPU first tries to get § SRAM is faster and much more expensive. them from cache. If they are not there, CPU will load them § DRAM needs to be refreshed thousands of times per second from the main memory. while SRAM does not need to be refreshed. • Modern microprocessors have separate cache memories for § Both types of RAM are volatile, meaning that they lose data and instructions. their contents when the power is turned off. 17 18 Static RAM Cells Dynamic RAM Cells • A static memory cell is a flip-flop. • A dynamic cell is a capacitor where absence or presence of • The transistors could be bipolar or MOS devices. charge denotes a stored one or zero. • The following figure shows a typical static memory cell. • The following figure shows a typical dynamic memory cell. The MOS capacitor can be written to by activating the row, or q C 3.5 V C´ word, line to turn the MOS transistor on and charge the capacitor through the column, or bit, line. The cell can be read by turning the transistor on and sensing a R1 R1´ q D1 D1´ voltage on the column. A A´ Row or R2 R2´ Word Line 2.5 V 0 V MOS Q1 Q1´ Transistor ROW_SELECT MOS Column or COLUMN LINES Capacitor Bit Line 19 20
ROM ROM Memory Cells (1/2) • ROM (Read Only Memory) is a type of non-volatile memory, meaning that the contents will not be lost when the power is Bit Line Bit Line Bit Line turned off. • There are various types of ROM memory chips. Word § Mask programmable ROM are programmed during the manufacturing Line Gate No Gate Gate stage and cannot be programmed by user. § Other ROM devices are field programmable and may be programmed by the user. These are called programmable read only memories., and include UV-erasable PROMs (EPROMs), one-time programmable (OTP) EPROMs, and fusible-link PROMs. § EPROMs are electrically programmable are erased by irradiating the chip through a quartz window with ultraviolet (UV) light. § An OTP EPROM is an EPROM without the window so that once programmed, it cannot be erased. § Another type of programmable read only memory is the electrically erasable PROM (EEPROM), which can be programmed and erased while in 21 22 use. ROM Memory Cells (2/2) EPROM Memory Cells (1/2) • The ROM memory cell is simply a wire or connection made UV Light to Erase Quartz Window or not made in the programming process. • The binary information is represented by the presence or Drain Source absence of the gate on the MOS transistor. • Activating the word line puts a one or zero on the bit line. SiO 2 Filed Oxide Field Oxide n+ n+ Electrons injected Si Floating Gate to program p-Substrate 23 24
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