Lec13-IO - io.1 EEL-4713 Computer Architecture I/O Systems...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: io.1 EEL-4713 Computer Architecture I/O Systems io.2 Outline ° I/O Performance Measures ° Types and Characteristics of I/O Devices ° Magnetic Disks ° Summary io.3 The Big Picture: Where are We Now? Control Datapath Memory Processor Input Output ° Today ` s Topic: I/O Systems Control Datapath Memory Processor Input Output Network io.4 I/O System Design Issues Processor Cache Memory - I/O Bus Main Memory I/O Controller Disk Disk I/O Controller I/O Controller Graphics Network interrupts • Performance • Expandability • Resilience in the face of failure io.5 Types and Characteristics of I/O Devices ° Behavior: how does an I/O device behave? • Input: read only • Output: write only, cannot read • Storage: can be reread and usually rewritten ° Partner: • Either a human or a machine is at the other end of the I/O device • Either feeding data on input or reading data on output ° Data rate: • The peak rate at which data can be transferred: - Between the I/O device and the main memory - Or between the I/O device and the CPU io.6 I/O Device Examples Device Behavior Partner Data Rate (MBit/sec) Keyboard Input Human 0.0001 Mouse Input Human 0.004 Graphics Display Output Human 800-8000 Network-LAN Input or Output Machine 100-1000 Wireless LAN Input or Output Machine 11-54 Optical Disk Storage Machine 80 Magnetic Disk Storage Machine 340-2560 io.7 Magnetic Disk ° Purpose: • Long term, nonvolatile storage • Large, inexpensive, and slow • Lowest level in the memory hierarchy ° Hard disks: • Rely on a rotating platter coated with a magnetic surface • Use a moveable read/write head to access the disk • Platters are rigid ( metal or glass) • High density • High data access rate: disks spin fast, plus can incorporate more than one platter and r/w head Registers Cache Memory Disk io.8 Organization of a Hard Magnetic Disk ° Typically, 10,000-50,000 tracks per surface • 100-500 sectors per track ° A sector is the smallest unit that can be read/written • 512Bytes – 4096Bytes ° Early days: all tracks had the same number of sectors • Zone bit recording: record more sectors on the outer tracks Platters Track Sector io.9 Magnetic Disk Characteristic ° Cylinder: all the tracks under the head at a given point on all surface ° Read/write data is a three-stage process: • Seek time: position the arm over the proper track • Rotational latency: wait for the desired sector to rotate under the read/write head • Transfer time: transfer a block of bits (sector) under the read-write head ° Average seek time as reported by the industry: • Typically in the range of 3 ms to 14 ms • (Sum of the time for all possible seek) / (total # of possible seeks) ° Due to locality of disk reference, actual average seek time may: • Only be 25% to 33% of the advertised number Sector Track Cylinder Head Platter io.10 Typical Numbers of a Magnetic Disk ° Rotational Latency: • Most disks rotate at 5K-15K RPM • Approximately 4-12ms per revolution...
View Full Document

This note was uploaded on 01/09/2012 for the course EEL 4713 taught by Professor Staff during the Spring '11 term at University of Florida.

Page1 / 18

Lec13-IO - io.1 EEL-4713 Computer Architecture I/O Systems...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online