1. Memory Allocation BIOS Operating System Program Data Program 1
Free Memory
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2. Memory System http://www.semiconductorscentral.com/memory_page.html
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3. Storage Speeds
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4. Making It Go Faster
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5. Storage Evolution
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6. HDD Evolution Track density≈30,000/inch Linear density≈33Mbits/inch
Areal density≈1Tbits/in²
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7. HDDs: Fragmentation Files begin life as contiguous locations on HDD
Files grow, shrink, are deleted, or are greatly expanded over time
As this happens, pointers are put in original locations, telling the HDD where the other portions of these files are.
Eventually, reading an entire file can require access to dozens of different locations on the HDD, which greatly increases read time.
Deframenting an HDD restores their contiguous locations, reducing read time.
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8. HDDs: Fragmentation Track 1 Track 2 Track 3 Track 4 Track 5 Track 6
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9. HDDs: Fragmentation Track 1 Track 2 Track 3 Track 4 Track 5 Track 6
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10. HDDs: Fragmentation Track 1 Track 2 Track 3 Track 4 Track 5 Track 6
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11. HDDs: Fragmentation Track 1 Track 2 Track 3 Track 4 Track 5 Track 6
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12. HDDs: Fragmentation Track 1 Track 2 Track 3 Track 4 Track 5 Track 6
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13. HDDs: Fragmentation Track 1 Track 2 Track 3 Track 4 Track 5 Track 6
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14. Interrupts Most common way for computers to handle I/O
Each core can handle separate interrupts
Handling interrupts quickly gives the appearance of multi-tasking
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15. Internal I/O Industry Standard Architecture (ISA) Extended ISA (EISA)
32 Mbps; 1982 (IBM PC)
Extended ISA (EISA)
64 Mbps; 1988
Peripheral Component Interconnect
(PCI)
132 Mbps; 1992
PCI-eXtended (PCI-X)
266 Mbps; 1998
PCI-e or PCI-E
v 1.0: (2003) 250 MBps/lane, 16 lanes = 4 GBps
v. 2.0: (2007) 500 MBps/lane, 32 lanes = 16 GBps (5 GT/s)
v. 3.0: (2012) – released Nov 2010; 8 GT/s, reduced overhead
V. 4.0: (2015) – 16 GT/s, still over copper
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16. External I/O Small Computers System Interface (SCSI)
50 Mbps, 1984; iSCSI, 2005, 1 Gbps.
Universal Serial Bus (USB)
v. 1.0: 12 Mpbs; 1994; v. 2.0: 480 Mbps (2000); v. 3.0: 4.8 Gbps (2010)
Firewire (AppleTalk; IEEE 1394)
400 Mbps (1996); 800 Mbps (2002); 1.6 Gbps (2007); 3.2 Gbps (2010)
Ethernet
10 Mbps (1984); 100 Mbps (1995); 1 Gbps (2000); 10 Gbps (2007); 40 Gbps (2010)
FibreChannel (FC)
2 Gbps (2005); 10 Gbps (2010)

17. External I/O Thunderbolt
10 Gbps
4 lanes, differential, 5.4 Gbps/lane
15 ft (5m) with copper; 100 m with mmf
Both PCI-e and DisplayPort
NOTE: preceding examples are NOT exhaustive in any way – just examples of what has been done.
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18. Cooperative Quiz 1 Which types of storage are volatile? SRAM DRAM
HDDs (hard-disk drives)
Flash memory
SSDs (solid-state drives)
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19. Cooperative Quiz 1 Which types of storage are volatile? SRAM DRAM
HDDs (hard-disk drives)
Flash memory
SSDs (solid-state drives)
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20. Cooperative Quiz 2
Which types of storage have fast read times (<100 ns)?
SRAM
DRAM
HDDs (hard-disk drives)
Flash memory
SSDs (solid-state drives)
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21. Cooperative Quiz 2
Which types of storage have fast read times (<100 ns)?
SRAM
DRAM
HDDs (hard-disk drives)
Flash memory
SSDs (solid-state drives)
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22. Cooperative Quiz 3
What is HDD defragmentation? (hint, hint)
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23. Cooperative Quiz 3 What is HDD defragmentation? (hint, hint)
Rewriting all the files on the HDD so that each file is contiguous. It reduces access time.
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