Chapter 2 Lecture 5 Computer Systems Organization

Transcription

1 Chapter 2 Lecture 5 Computer Systems Organization This chapter provides an introduction to the components Processors: Primary Memory: Secondary Memory: Input/Output: Buses, Data Transfer, Input/Output, and more The Old Version Simple one-bus system Figure Omni-bus, Unibus, etc. single bus system Important aspects of buses: One operation at a time wide buses include address, data, and control narrow bus multiplexes address on one cycle with data on the next DMA Cycle stealing Direct Memory Access allows CPU or peripheral device to move data independently of the CPU When peripheral seizes the bus when normal CPU requests would be performed. 1 of 8 ECE 357

2 Multiple Buses and formats are currently used in computers ISA Industry Standard Architecture (original PC bus) EISA Extended ISA (PATA) VL-Bus Video Electronics Standards Association (VESA) Local Bus (graphics speed) PCI Peripheral Computer Interconnection Figure Typical Pentium Class PC Another version: 2 of 8 ECE 357

3 Bit-map terminals (more things for data rate computations) Three color guns or LCD elements that combine to provide color. (one for gray scale only) Writing pixels to the screen (4:3 aspect ratios) VGA 640 x 480 (480i) SVGA 800 x 600 XVGA 1024 x x 960 HD 1440 x 1080 (Anamorphic widescreen: compressed 1920 x 1080) 1600 x 1200 Writing pixels to a high definition screen (16:9 aspect ratios) 640 x x x 576 HD 1280 x 720 (720p) 1600 x 900 HD 1920 x 1080 (1080i, 1080p) Nomenclature in parenthesis refer to video formats for signal transmission Color Video/Graphics Color is a combination of Red, Green and Blue for an additive model. (RGB system) - for printing and graphics there is an alternate subtractive model - CMYK 3 of 8 ECE 357

4 True Color vs. Indexed Color For flexible true color, we like to assign 8-bits per color 3 Bytes one byte for each color - 2^8 levels or 256 each 24-bit RGB representation millions of colors This approach takes 3 Bytes per pixel of color, a quantity deemed too high. color palette interpretation of 1 Byte into or 256 separate indexed color choices of 3 Byte RGB colors 1 Byte 2^8 levels or 256 colors (predefined i9ndexed set of levels for RGB) Cross section of a raster scanned CRT. Color monitors also perform interlacing. Full motion video requires updated frame rates of 25 frames per second or higher (30 preferred). 4 of 8 ECE 357

5 LCD Displays are becoming standards 5 of 8 ECE 357

6 Other Peripheral Devices and Codes (RS-232, Modem, ASCII) Chapter 10, Computer System Design and Architecture, V. Heuring and H. Jordan, Addison Wessley, 1997, ISBN X RS-232 serial data transfers Nine wire cable structure Three wire minimum serial connections RX TX GND UART Universal Asynchronous Receiver/Transmitter Rates: 1200, 2400, 9600, 19200, 28800, 33600, 56k Buad (Bits per second) Fig. 10.5, Computer System Design and Architecture, V. Heuring and H. Jordan, Addison Wessley, 1997, ISBN X Fig. 10.6, Computer System Design and Architecture, V. Heuring and H. Jordan, Addison Wessley, 1997, ISBN X 6 of 8 ECE 357

7 MODEM Modulator/Demodulator ( ) Use frequency modulation techniques to transmit serial digital data Convert digital data 0 s and 1 s to audio tones. Allow data transmission on an analog phone line (audio). Telephone lines allow tones from 50Hz to 3500 Hz A nominal maximum symbol rate for audio phone lines is 2400 symbols per second. The FSK symbol for 0/1 would be two frequencies, one frequency for each value for the upstream and downstream paths (a 300 baud modems use two at 1,070 and 1,270 Hz and another two at 2,025 and 2,225 Hz). The Shannon capacity limit for a 4 khz analog channel is approximately 35 kbps. Alternate symbol encodings include: Quadrature Amplitude Modulation (QAM), Trellis Code Modulation (TCM) 7 of 8 ECE 357

8 ETHERNET ( ) Chapter 10, Computer System Design and Architecture, V. Heuring and H. Jordan, Addison Wessley, 1997, ISBN X Developed at Xerox in 1970s, now the most popular LAN Physical layer can be coaxial cable or twisted pair (telephone cable) Broadcast medium: every controller receives and examines every packet. Collisions possible Data link layer: packets from 64 to 1518 bytes long (plus a preamble of 8 bytes) Connectionless protocol, packets are going to the destination with no response required. MAC Addresses are 48 bits long, organized as 6 8-bit octets (i.e. XX-XX-XX-XX-XX-XX) Addresses guaranteed to be globally unique Cables and Data Rates Nominal media data rates: 10Base-T 10 Mbps, 100Base-T 100 Mbps, Gigabit 1 Gbps For more information on the older aspects of Ethernet connections and networking, see the web pages slides from H&J Chap 10 Slides (10-21 to 10-31). 8 of 8 ECE 357