Transcript Šiuolaikinių kompiuterių architektūra

COMPUTER
ARCHITECTURE
(for Erasmus students)
Assoc.Prof. Stasys Maciulevičius
Computer Dept.
[email protected]
[email protected]
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Periphery equipment
 Periphery equipment is electronic
equipment that can be plugged into a
computer using one of its input/output
interfaces (serial port, parallel port, USB
bus, FireWire bus, SCSI interface, etc.),
most often by using a connector
 Periphery equipment is therefore external
computer components
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Periphery equipment
 Periphery equipment is generally grouped into the
following categories:
 storage periphery equipment: input/output periphery
equipment that can permanently store data (hard disk, CDROM, DVD-ROM, etc.);
 display periphery equipment: output periphery equipment
that provides a visual representation to the user, such as a
monitor;
 capture periphery equipment: allows the computer to receive
specific data such as video data or scanner;
 input periphery equipment: periphery equipment only capable
of sending information to a computer, for example pointing
devices (mouse) or the keyoard.
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External memory
As long-term storage in computers are
used:
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hard drives
CD-ROM, CDs (optical compact discs)
DVDs
flash memory
floppy disks (outdated)
strimmers.
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External memory
Access modes:
 direct access
 sequential access
Parameters:
 capacity
 access time
 data transfer spped
 relative price
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First HD
 IBM announced the IBM 350 storage unit
as a component of the RAMAC 305
computer system on September 13, 1956
 Assembled with covers, the 350 was 60
inches long, 68 inches high and 29 inches
deep
 It was configured with 50 magnetic disks
containing 50,000 sectors, each of which
held 100 alphanumeric characters, for a
capacity of 5 million characters
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First HD
• 50 platters
• 1 head
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First HD
 Disks rotated at 1,200 rpm, tracks (20 to the
inch) were recorded at up to 100 bits per
inch, and typical head-to-disk spacing was
800 microinches
 The execution of a "seek" instruction
positioned a read-write head to the track
that contained the desired sector and
selected the sector for a later read or write
operation
 Seek time averaged about 600 milliseconds
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Hard disk drive
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Hard disk drive
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Platters vary in size and hard disk drives come in
two form factors, 5.25in or 3.5in
Typically two or three or more platters are stacked
on top of each other with a common spindle
Tthe head flies a fraction of a millimetre above the
disk. On early hard disk drives this distance was
around 0.2mm. In modern-day drives this has been
reduced to 0.07mm or less
There's a read/write head for each side of each
platter, mounted on arms
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Hard disk drive
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The disk controller controls the drive's servomotors and translates the fluctuating voltages from
the head into digital data for the CPU
More often than not, the next set of data to be read
is sequentially located on the disk. For this reason,
hard drives contain between 256KB and 8MB of
cache buffer in which to store all the information in
a sector or cylinder in case it's needed. This is very
effective in speeding up both throughput and
access times
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Technical specifications
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Capacity: Amount of data which can be stored on a hard
drive
Transfer rate: Quantity of data which can be read or
written from the disk per unit of time. It is expressed in bits
per second (Mb/s)
Rotational speed: The speed at which the platters turn,
expressed in rotations per minute (rpm for short). Hard
drive speeds are on the order of 7200 to 15000 rpm. The
faster a drive rotates, the higher its transfer rate. On the
other hand, a hard drive which rotates quickly tends to be
louder and heats up more easily
Latency (also called rotational delay): The length of time
that passes between the moment when the disk finds the
track and the moment it finds the data
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Technical specifications
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Average access time: Average amount of time it takes the
read head to find the right track and access the data. In
other words, it represents the average length of time it takes
the disk to provide data after having received the order to
do so. It must be as short as possible
Radial density: number of tracks per inch (tpi).
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Linear density: number of bits per inch (bpi) on a given track.
Surface density: ratio between the linear density and radial density
(expressed in bits per square inch).
Cache memory: Amound of memory located on the hard
drive. Cache memory is used to store the drive's most
frequently-accessed data, in order to improve overall
performance
Interface: the connections used by the hard drive. The main
hard drive interfaces are IDE/ATA, SATA, SCSI
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Information on disk
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Information on disk
 The data is organised in concentric circles called
"tracks"
 The tracks are separated into areas called
sectors, containing data (generally at least 512
octets per sector)
 The term cylinder refers to all data found on the
same track of different platters
 The term clusters (also called allocation units)
refers to minimum area that a file can take up on
the hard drive
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Hard disk
Formatted and unformatted disk
capacity
Capacity = Number_of_cylinders 
Number_of_surfaces 
Number_of_sectors/cilinder 
sector_size
Modern (2009) disk capacity is 100-500 GB,
advanced disks even reached 1-2 TB
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Hard disk
Access time depends on the following
parameters:
 cylinder seek time
 delay on the rotation
 transfer time
Information transmission time depends on:
 recording density and
 disk rotational speed
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Old disk - MD Maxtor 33073H3
Capacity
30 GB
ATA-5 / Ultra ATA/100
Integrated interface
Buffer size/ type
Surfaces / Heads
Platters
Arreal density
2 MB SDRAM
3
2
14.7 Gb / sq. in. max
Track density
Linear density
Bytes per sector/ Block
34 000 tpi
354 - 431 kb/colyje
512
Sectors in track
373 - 746
60 032 448
Sectors in disk
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Old disk - MD Maxtor 33073H3
Seek time (read op.)
Track-track
Average
1.0 ms
9.5 ms
Rotational speed(+ 0.1%)
Data transfer rate
To/from interface (Ultra ATA/100, DMA M5)
To/from interface (PIO 4 / Multi-word DMA
M5)
To/from medium
Start time
5400 RPM
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to 100 MB/s.
to 16.7 MB/s
to 46.7 MB/s
8.5 s
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Recording methods
Traditional recording method –horizontal recording:
N
S N
S S
N S
N N
S S
N N
S
Now a new recording method is in use – vertical
(perpendicular) recording. The bits are in a
vertical arrangement instead of horizontal in order to
take up less space. By 2010, perpendicular
densities are expected to exceed 500 Gb/sq. in.
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S
N
N
S
S
N
S
S
S
N
N
S
S
N
N
S
N
N
N
S
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Disk density
Disk Density is measured and is also
called areal density
 Now how is this density calculated? For
the most part the density we measure in
Bit per Inch (BPI) and track per inch (TPI)
 When we multiply the TPI and BPI we get
areal density
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Disk density
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Disk density - 2008
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Current recording density is about 250 GB per
square inch
To achieve vertical recording density of over 610
Gbit per square inch the Hitachi engineers had to
improve on existing technology
In the laboratory demonstration the linear
recording density is 1.6 million bits per inch and
the track density is 381,000 tracks per inch
The read head has a width of 40 nm (a feature size
smaller than Intel’s CPU process technology )
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Disk capacity
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Terrabyte drives - 2009
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Flash memory
 Flash memory refers to a particular type of EEPROM
(Electronically Erasable Programmable Read Only
Memory). It is a memory chip that maintains stored
information without requiring a power source
 Flash memory differs from EEPROM in that
EEPROM erases its content one byte at a time. This
makes it slow to update. Flash memory can erase its
data in entire blocks, making it a preferable
technology for applications that require frequent
updating of large amounts of data
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Flash memory
Flash memory combines several useful
features:
 high packing density (the cell is 30% smaller than
the DRAM)
 maintaining stored information without requiring a
power supply
 erasing and recording information using electrical
signals
 low energy consumption
 high reliability and
 low price
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Flash memory
 Flash memory is used primarily as:
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rarely rewritten (eg, BIOS) memory
compact exchangeable memory in computers (USB
keys)
compact exchangeable memory in PDAs, digital
cameras, digital audio players etc.
 E.g., Kingston
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DataTraveler 200 is 32GB-128GB capacity
(DataTraveler 300 – 256GB), has 20MB/sec read,
10MB/sec write speed
DataTraveler Vault has 256-AES hardware-based
encryption, 2GB-32GB capacity
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Solid state memory
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Solid state memory or a solid state drive (SSD) is a
device that uses no moving parts to store data
The first ferrite memory SSD devices, or auxiliary memory
units as they were called at the time, emerged during the
era of vacuum tube computers
In the 1970s and 1980s, SSDs were implemented in
semiconductor memory for early supercomputers of IBM,
Amdahl and Cray; however, the high price of the SSDs
made them quite seldom used
RAM "disks" were popular as boot media in the 1980s
when hard drives were expensive, floppy drives were slow
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Solid state memory
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2004: Texas Memory Systems' RamSan-325 can carry
out 250,000 I/O operations a second.
Available in capacities of 128, 96, 64, and 32 gigabytes,
RamSan-325 accelerates I/O intensive applications by
delivering random data at sustained rates exceeding 1.5
Gbps
Non-volatile product has high availability architecture with
redundant and hot swappable power supplies, redundant
batteries
However, build using 512Mb of DDR RAMs, device was
quite expensiv – 16 GB device costs $36.000
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Solid state memory
 Now fash memory is media for building solid state
memory devices
 These devices can range from 8MB all the way
up to 32GB (or even more)
 Flash memory used as a hard drive has many
advantages over a traditional hard drive
 It is silent, much smaller than a traditional hard
drive, and highly portable with a much faster
access time
 However, the advantages of a traditional hard
drive are price and capacity
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SSD
 Most SSD manufacturers use non-volatile flash memory to
create more compact devices for the consumer market
 These flash memory-based SSDs, also known as flash
drives, do not require batteries. They are often packaged
in standard disk drive form factors (1.8-, 2.5-, and 3.5-inch)
 In addition, non-volatility allows flash SSDs to retain
memory even during sudden power outages, ensuring data
persistence
 Flash memory SSDs are slower than DRAM SSDs and
some designs are slower than even traditional HDDs on
large files, but flash SSDs have no moving parts and thus
seek times and other delays inherent in conventional
electro-mechanical disks are negligible
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SSD prices – some facts
 In March 2007 SanDisk announced it was offering its 32GB 2.5"
SATA SSD to oems for $350. In July 2008 OCZ said its fast Core
series 2.5" SSDs were available with an price of $169 for 32GB
 Also in July 2008 Advanced Media said its fast-ish Ultra-S Plus
family of SATA 2.5" MLC flash SSDs would be available with low
volume prices as follows:- 32GB - $168, 64GB - $294, 128GB $537
 October 2009: Active Media Products launched its Aviator 312
line of bus powered fast USB 3.0 external SSDs with R/W
speeds upto 240MB/s and 160MB/s respectively. Measuring less
than 3" long and only 0.2" thin, the A312 is smaller than a credit
card and is designed to fit in a pocket. Capacity options include:16GB ($89), 32GB ($119) and 64GB ($209)
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SSD and HD
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OCZ SSD in 2009
 Available in 30GB, 60GB, 120GB, and 250GB
capacities
 Read: up to 155 MB/sec, Write: up to 90 MB/sec,
Seek: <.2-.3ms
 Slim 2.5" Design, 100 x 70 x 9.3mm, Lightweight
77g
 Operating Temp: -10C ~ +70C
 RAID Support
 Mini USB 2.0 Port
 MTBF 1.5 million hours
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250GB SSD price at amazon.com - $596.08
(2009.10.20)
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OCZ SSDs in 2009
 At Cebit 2009, OCZ demonstrated a 1 TB flash
SSD using a PCI Express x8 interface. It achieves
a minimum read speed of 654 MB/s and
maximum read speed of 712 MB/s
 According to Revioo.com, $1500 is the expected
price
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Hybrid hard drive
 Certain technology meets half-way between hard
drive and solid-state drive, such as the hybrid drive,
and ReadyBoost
 A hybrid drive, sometimes called hybrid hard drive,
uses a small SSD as a cache. The SSD is often
flash memory
 ReadyBoost is a part of the Microsoft Windows
Vista operating system that uses compatible flash
memory as a drive for a disk cache
 A random disk read from the cache is generally 80
to 100 times faster than random disk read from a
traditional hard drive
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Hybrid hard drive
 Certain technology meets half-way between hard
drive and solid-state drive, such as the hybrid drive,
and ReadyBoost
 A hybrid drive, sometimes called hybrid hard drive,
uses a small SSD as a cache. The SSD is often
flash memory
 ReadyBoost is a part of the Microsoft Windows
Vista operating system that uses compatible flash
memory as a drive for a disk cache
 A random disk read from the cache is generally 80
to 100 times faster than random disk read from a
traditional hard drive
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