Chapter 6 - Memory and Data Storage Flashcards
What is a Musical Instrument digital interface?
MIDI for short
the storage of music files - consists of lists of commands which instruct a device on how to produce a musical note/sound
What is MPEG-3 (MP3)?
uses audio compression to store music in MP3 file format
What is MPEG-4 (MP4)?
can store multimedia rather than just music
What is Joint Photographic Experts Group (JPEG)?
JPEG uses a lossy format file compression method to store photographs at a reduced file size
What is lossless file compression?
all the data from the original files are reconstructed when the file is uncompressed
What is lossy file compression?
unnecessary data is removed forming a file that cannot be reconstructed to its original file
What are examples of primary memory?
RAM, SRAM, DRAM, ROM
What are examples of secondary storage?
hard disk drives
solid-state drives
offline storage (CDs, DVDs, DVD-RAM, DVD-ROM and blu-ray disks)
Why are MIDI files so small?
don’t contain actual audio tracks
suitable for storing sounds/music on devices with limited memory
What is perceptual music shaping?
removing sounds that the human ear can not clearly distinguish
How is text usually stored?
ASCII file format
lossless: accuracy of data is important
Which primary memory is volatile?
RAM
Can RAM be written to and read from?
yes
How does DRAM work?
needs to be constantly refreshed to retain the data
uses millions of transistors and capacitators
How does SRAM work?
does not need to be constantly refreshed to retain its data
uses flip-flops
Which primary memory is non-volatile?
ROM
What does ROM store?
used to store start-up procedures or BIOS
What do hard disk drives use?
circular platters coated in magnetic material
What is used so that all surfaces can be accessed?
read-write heads
How is data stored in hard disk drives?
sectors and tracks in block
What is latency?
the time taken for a specific block of data on a track to rotate around to the read-write head
Why is latency not an issue in SSD?
they have no moving parts
all data retrieved at the same rate
therefore no latency
What do the most common types of SSD use to control the movement of electrons (and therefore data)?
NAND chips
What do EEPROMS (electronically erasable programable read-only memory) use?
NOR chips
What are the advantages of SSDs over HDD?
more reliable and robust (no moving parts) much lighter and thinner consumer less power and run cooler does not need to get up to speed faster data access rate
What do CDs and DVDs use to write and read data?
red laser light
What does the suffix -R on CDs/DVDs mean?
write once and then only be read
What does the suffix -RW on CDs/DVDs mean?
can be written to and read from several times
Why do DVDs hold more data than CDs?
dual layering technology (they have two individual recording layers)
What type of technology is nearly obsolescent?
DVD-RAM
How does DVD-RAM work?
uses a number of concentric tracks enabling simultaneous read-write operations to take place
Why are DVD-RAM ideal for archiving data?
they have great longevity
What do blu-ray disks use to read and write data?
blue laser light
Why can blu-ray disks hold more data than CDs and DVDs?
wavelength of blue light is 405nm
wavelength of red light is 650nm
can store more data
Why do blu-rays not suffer from birefringence (light reflection into two separate beams causing reading errors)?
they use single polycarbonate disks rather than DVDs which use a sandwich of two polycarbonate disks
What technology do flash memory/memory sticks use?
solid-state technology
How do flash memory/memory sticks usually connect to the computer?
USB port
Why are flash memory/memory sticks ideal for transferring files and photos between different computers?
small and lightweight
What needs to happen for flash memory/memory sticks to retain their data integrity?
read every now and again
