CS 2200

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CS 2200

• Presentation 14
• Input/Output
• Part I

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Our Road Map
Processor
Memory Hierarchy
I/O Subsystem
Parallel Systems
Networking
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First there was I/O...

• then computers?

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Roots of I/O Devices

• Telecommunications
• Smoke signals
• Drums
• Optical telegraphy
• Electrical telegraphy
• Wireless telegraphy
• Teletype
• Television
• etc.

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Roots of I/O Devices

• Control/Tabulation
• Jacquards Punched Cards
• Holleriths tabulating machines
• IBM
• Other technologies
• Magnetic recording
• Wire
• Tape

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Characterization

• Behavior
• Input
• Output
• Storage

Computer
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Characterization

• Partner
• Human
• Machine

Computer
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Characterization

• Data Rate
• Peak rate

Computer
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Types

• Device Behavior Partner DataRate
  kb/s
• Keyboard I Human 0.01
• Mouse I Human 0.02
• Voice Input I Human 0.02
• Scanner I Human 400
• Voice Output O Human 0.6
• Line Printer O Human 1
• Laser Printer O Human 200
• Graphics Display O Human 60,000
• Modem IO Machine 8
• Network IO Machine 6,000
• Floppy Disk S Machine 100
• Optical Disk S Machine 1,000
• Magnetic Tape S Machine 2,000
• Magnetic Disk S Machine 10,000

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Mouse
I got the idea for the mouse while attending a
talk at a computer conference. The speaker was so
boring that I started daydreaming and hit upon
the idea. Doug Englebart

• Uses mechanical counters or optical devices to
  generate pulses which increment or decrement
  counters
• Counter values determined by polling.

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Magnetic Disks

• Fixed head drums
• Disks
• Removable disk packs
• Floppy disk
• Invented for IBM Field Engineers
• Contact
• Slow speed

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Magnetic Disks

• Hard disk
• Higher speed
• Larger
• Higher Density
• Multiplatter
• Flying heads!

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Magnetic Disks
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Magnetic Disks

• Hard disk
• Higher speed (3600 - 7200)
• Larger
• Higher Density
• Multiplatter
• Flying heads!
• Performance
• Seek time (8-20 ms or faster)
• Rotational latency (4-8 ms)
• Transfer rate 2-40 MB/sec

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Magnetic Disks

• Surfaces (2 per platter), tracks, sectors, head
  assembly
• all tracks have same number of sectors
• all sectors record same number of bits
• logical cylinder
• a set of corresponding tracks on all surfaces
• characteristics
• seek time, rotational latency, data transfer rate
• Typical numbers
• 20 surfaces, 1000 tracks, 128 sectors

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Disk Terminology
Cylinder Track 'x' on all platters/surfaces
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Questions?
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Hooking everything up.
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Five Classic Components
Processor
Memory
Control
Datapath
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How do we connect to the CPU?
One way
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Another...
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(No Transcript)
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Buses

• Recall that we said...
• Buses consist of address, data and control lines.
• As noted numerous bus configurations have been
  developed
• Processor and device speeds have changed
• Economics have changed
• New device types
• etc.

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But how do we do I/O???

• Memory mapped I/O
• To the programmer the device just looks like
  memory addresses.
• Read or Write or Both
• Load/store with these addresses to make I/O
  happen.
• Usually mapped to OS address space
• Programmer requests I/O via system call

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Typical Simple Output Device
Command Ready
Write
0
0
0
0
0
0
0
0
Control
W/O
Error
Busy
0
0
0
0
0
0
0
0
Status
R/O
0
0
0
0
0
0
0
0
Data
W/O
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But how do we do I/O???

• Special Instructions
• May have separate I/O Address space
• Typical instructions (Intel Pentium)
• IN Move data from I/O Port to register
• OUT Move data from register to I/O Port
• INS Move data from I/O Port to memory
• OUTS Move data from I/O Port to memory

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But how do we do I/O???

• I/O Device communicates to processor via
  interrupts
• Data Transfer
• Program Control
• Read data from I/O device into register
• Store from registers into memory
• DMA
• CPU Initiates request
• Provide address and count
• Transfer occurs via bus from device to memory

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Questions?
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(No Transcript)