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Datorteknik IODevices bild 1 I/O Devices Connected to the Backplane bus –Hard disk controllers –Graphics adapters –Serial I/O –Sound Cards –Virtual Reality.

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Presentation on theme: "Datorteknik IODevices bild 1 I/O Devices Connected to the Backplane bus –Hard disk controllers –Graphics adapters –Serial I/O –Sound Cards –Virtual Reality."— Presentation transcript:

1 Datorteknik IODevices bild 1 I/O Devices Connected to the Backplane bus –Hard disk controllers –Graphics adapters –Serial I/O –Sound Cards –Virtual Reality Helmet Gloves Quake controller

2 Datorteknik IODevices bild 2 I/O Performance I/O Bandwidth –How much data can we move from A to B/time unit –How many I/O operations can we perform/time unit Latency per access –Low long do we have to wait to get access Response time –The total time to perform a task

3 Datorteknik IODevices bild 3 Disk I/O Performance Supercomputer Benchmarks –Batch jobs Large files Throughput of data Transaction Processing –I/O Rate Many small accesses File System –MakeDir, Copy, ScanDir, ReadAll, Make

4 Datorteknik IODevices bild 4 Types of I/O Devices Behavior –Input, Output, Storage Partner –Human/Machine Data Rate –Human Keyboard, 10b/sec Voice, 100kb/sec –Hard Disk 10Mb/sec

5 Datorteknik IODevices bild 5 Hard disk 2-20 Platters RPM 1-10 Inch Diameter tracks/surface sectors/track Cylinder –All tracks at one position Sectors Track 1-10 inches 2-20

6 Datorteknik IODevices bild 6 Hard Disk Average Seek Time (average time to move a track) –8-12 ms –Does not consider locality Rotational Latency –4-8 ms –Often dominates over Seek Time –Start reading to ring-buffer when track reached Transfer Rate –2-10 Mb/sec 123…303132

7 Datorteknik IODevices bild 7 Other Properties Storage Size 500Mb-10Gb Cylinder 0, Boot Block Partition Information –Usually a Physical Disk is devided into Smaller Partitions –File System Information File System –The “data structure” for storing files and folders –Usually Hierarchical Folders, sub folders and files File types, (program/data-format) and protection bits

8 Datorteknik IODevices bild 8 SCSI/EIDE I/O Bus SCSI –General purpose interface for HDs, Scanners, Streamers, etc –Both synchronous/asynchronous operation –5Mb/sec (standard SCSI higher for wide and ultra-wide) –7 Devices/Bus Mastering/Self Selection Arbitration EIDE –HDs and HD like devices (CR-ROMs etc) –Synchronous –5Mb/sec –2 Devices on each controller –HD controller on Interface

9 Datorteknik IODevices bild 9 Networks RS-232, copper wire 19.2kbit/sec –Serial Point to Point Protocol (ppp) LAN (Local Area Network), coaxial 100Mbit/sec –Ethernet 10Mbit/sec –Package bytes –Actually a bus with collision detection Long Haul Network, fiber 1Gbit/sec –ARPANET (US government) became INTERNET –Packet Switched Networks

10 Datorteknik IODevices bild 10 Network File System Mounting Devices over the Network (usually LAN) Local and Network devices transparent to User Network Server - Local Client (a protocol) Needs support by the OS –Local TCP stack, handles streams of I/O –Network Server forwards these streams –“Samba Server” makes Unix devices available to PCs

11 Datorteknik IODevices bild 11 Graphics Adapters Each pixel uses a bit array (1-24bits) 1280*1024*24bits/pixel needs approximately 4Mb RedGreenBlue =24bits/pixel YellowWhite

12 Datorteknik IODevices bild 12 Graphics Adapter Design Needs to update the Screen times/sec (frames) At 80Hz*4Mb=320Mb/sec Huge Throughput We use special VRAM (Video RAM) –Shifts out bits to DAC at this high rate Usually contain a Graphics Accelerator, which –Move and Copy Blocks of data in local VRAM –Perform operations, like AND/EXOR (bit mask) –Functions Line, Polygon Fill –“3D” functions like: Polygon Shading, Texture Mapping etc.

13 Datorteknik IODevices bild 13 Video Application Example A system for real-time video recording/playback –A Frame Grabber, records video to HD –A Graphics Adapter displays video from HD 640*480*8bits/pixel (256 colors) –300kb/frame recording or playback We do NOT want CPU in data path

14 Datorteknik IODevices bild 14 Approach 1 The Frame Grabber records one Frame (300kb) to local buffer –Frame Grabber gives interrupt The OS sets up a DMA transfer from FG to RAM –The DMA gives interrupt The OS sets up a DMA transfer to HD –The DMA gives interrupt –The HD gives interrupt, data written to disk At 25 frames/sec (TV quality) this gives –2 (first to RAM then to HD) * 300 * 25 = 15Mb/sec Hmm, no Good! A lot bus activity, too high HD throughput (and this is for just recording)

15 Datorteknik IODevices bild 15 Approach 2 Put MPEG-2 hardware compression on the Frame Grabber, now only 30kb/frame –Frame Grabber gives interrupt The OS sets up a DMA transfer from FG to HD –The DMA gives interrupt –The HD gives interrupt, data written to disk At 25 frames/sec (still TV quality) this gives – 30 * 25 = 750kb/sec Simultaneous record/playback gives –1.5 Mb HD throughput, which is possible but still quite high –A lot of activity on the SCSI bus

16 Datorteknik IODevices bild 16 Approach 3 Frame Grabber –MPEG-2 hardware compression, now only 30kb/frame –Graphics Adapter, that can display MPEG-2 frames –SCSI bus to local HD for video storage –Interrupt each frame recorded, or finished playback sequence Best solution! Almost no bus PC bus activity You get what you pay for, this one will cost you $$$$

17 Datorteknik IODevices bild 17 High Fidelity Audio PCM 44.1 kHz 16bits Stereo (WAV/AIFF) 96 db signal/noice ratio Left Right 16 bit signed integer 16 bit signed integer

18 Datorteknik IODevices bild 18 Sound Cards Wave-Table playback –16 bit (Stereo at 44.1 kHz) –32 voices –5.6 Mb/sec (quite high bandwidth) WaveTable ROM/RAM Signal Processor MIX... DA/Filter Audio

19 Datorteknik IODevices bild 19 Audio I/O In/Out –Data Buffers –DMA Channel –IRQ (Interrupt number) 2 IRQ for full duplex operation 350kb/sec throughput on bus, OK In Buffer DSP DA/FilterAudio OutOut Buffer Filter/AdAudio In


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