Units



   KB: kilo byte (Kilo=Thousand=10^3) 
   MB: mega byte (Mega=Million=10^6) 
   GB: giga byte (Giga=Billion=10^9)
   TB: tera byte


FYI: International System of Units


When do you use bits and Bytes?
[any material that should appear in print but not on the slide] [any material that should appear in print but not on the slide] [any material that should appear in print but not on the slide] [any material that should appear in print but not on the slide]

Bits and bytes. Why it's important

You would treat a one ton object differently than a one pound object. Right?

Similarly, I want you to get a sense of how 1 KB files are different than a 1 GB file

Notes

Memory Hierarchy

- Can you make your computer go faster?







- Where Does Flash Memory Go?
Notes

Storage

Hard Disk Drive (HDD) being replaced by Solid State Drives (SSD)

Non-volatile. Data saved even when power off. This is where you store your files (semi)permanently.

  • Local: The drives inside your computer are called local (or internal) drives.



  • External: You can connect storage devices through a cable (Thunderbolt, Firewire, or USB) to your computer. They are called external drives.




  • Remote: Your storage device can be somewhere else accessed through the network (we call this remote). The lab has something called a RAID server connected to the network. It is basically a large hard disk. All your files in the lab are stored here.



RAM -- aka "memory":

Volatile storage. This is where the computer operates on your files.



  • Basic idea: files in hard disks are copied into RAM and then operated on. Why? Access to RAM is almost a million times (10^6) faster than to the hard disk.

  • Image files are LARGE. They get larger than it actually is when Photoshop operates on it. You think you opened a 200MB file but Photoshop may easily consume 800MB of memory when operating on it.

  • What happens if you run out of RAM to operate on?? The computer uses a trick called virtual memory to fool Photoshop and uses the hard disk as part of RAM.

    The effect, you actually can operate on data larger than the available RAM... but becomes really slooooooooow. (Hence, the suggestion to add more memory if your computer is running slow. This makes sense only if you are running slow because you don't have enough memory. Other programs use memory too. So if you quit programs and close files you are not using, you make more memory available.)


Notes

DML

Notes

Backup Media

CD-R: Really cheap
  • 670MB
  • Only for backup. Cannot edit files on CD-R.


DVD-R: Cheap
  • Single Layer (SL): 4.7GB
  • Double Layer (DL): 8.5GB
  • Only for backup. Cannot edit files on DVD-R.


External hard drives (or even iPhones/iPods)

2005 -- 500GB for $500
2007 -- 500GB for $300
2008 -- 500GB for $200
2010 -- 500GB for $100
2013 -- 1TB for $100+
2015 -- 2TB for $100+
2016 -- 2TB for < $100
2017 -- 4TB for $100+

[Does this follow ******'s Law?]


Comes with different interfaces (Firewire, USB, Thunderbolt, eSATA -- do not buy eSATA yet as we have no interface).
Can edit files on disk.


USB flash drives

  • GB for tens of dollers
  • Useful for transferring files between machines


Notes

Interface

USB:

2 Mbit/sec (1.5 MBytes/sec), with USB 2.0 up to 480 Mbit/sec (60 MBytes/sec), USB 3.0 up to 5GBps (640 MBytes/sec)



Thunderbolt

10 Gbps (approx 1.2 GBytes/sec)



We recommend a USB 3.0 external hard drive. Then you will be able to connect to Mac and PC.

Network

Ethernet: a wired network connection. Pretty fast. Tens to hundred(s) Mbits/sec. You are often sharing bandwitdh with others though...

Wireless (Wi-Fi): not so fast. Tens of Mbits/sec.



Notes