AboutBits
andBytes
and
FileTransfer
for
iPadUsers
PCs,iPadsandiPhones
have:
• memorychipstostore
data;
• processingchipsthat
manipulatedata—i.e.
allowittobeedited,
movedandcopied,
displayedandplayed.
Anunderstanding
thebinarynatureofthe
datafilesthatstore
digitalaudio,booksandphotos
andtheamountofmemoryspace
thatsuchfilesoccupy
preparesusformanaging
thecontentofouriPads.
Hereisasimplified
diagramofaniPad’s
memoryand
processingcircuitry.
Steppingthroughafew
processorcycleswill
helpusunderstand
whatdatais
andhowitisstored
andprocessed.
ThereisaMasterClock.
Eachtimeitticks,aprocessoccurs.
Avaluefrommemoryhasbeenputin
InputRegisterA.
Asecondvaluehasbeenputin
InputRegisterB.
Theadditionoperationhasbeenputinthe
InstructionRegister.
Theinstructionhasbeenprocessedandthe
resultputintheResultRegister.
Theresultmaynowbeputinmemory,or
outputtotheScreenortotheWiFi,etc…
Inputs
Outputs
Shownabove
aresomeofthewaysdata
isgotintoandoutofaniPad.
Digitial devicesstoredataasbinarydigits— ones andzeros
Voltagelevels:ON andOFF,representthedigits.
Agroupof8bitsiscalledaByte—
enoughbitstoencodeasingleletterorsymbol.
Thebinarycodesfortheletters“O”and“K”
in8-bitASCIIcharactercodeareshownabove.
HerearetheASCIIcodesfor:
• TheDigits
• TheUpperCaseLetters
• TheLowerCaseLetters
• SomePunctuationCharacters
8-bitASCIIcanrepresentonly256
differentcharactersymbols.Newer
codingsystemsarenowusedto
representthefullrangeof
charactersrequiredtorepresentthe
world’slanguages.
A
Kilobyte
1KB
AThousandBytes
Enoughspace
tostoreabout
halfapageof
single-typed
Text.
A
Megabyte
1MB
AMillionBytes
Enoughspace
tostorethetext
ofanovel.
A
Megabyte
1MB
AMillionBytes
Enoughspace
tostore
around3minutesofAudio
HalfasecondofDigitalAudio—Twotracksofastereorecording.
WhenCDqualityaudioisrecorded,
amplitudevaluesaresampled44,100timespersecond.
A
Megabyte
1MB
AMillionBytes
enoughspace
tostore
a mediumresolution
photo
Ifwezoominonthetoweronthepeak
Theimagepixels
becomevisible.
Eachpixelinthe
imageis
recordedby
threenumbers:
thered,green
andblue
brightness
values.
A
Gigagabyte
1GB
AThousandMB
ABillionBytes
Enoughspace
tostorethetextof
around1000books
A
Gigagabyte
1GB
AThousandMB
ABillionBytes
Enoughspace
tostore
10to40AudioCDs1
Theamountofspacerequireddependsupontheselectedbit-rate.Higherquality
sounduseshigherbit-ratesandoccupiesalargeramountofspace.
1
A
Gigagabyte
1GB
AThousandMB
ABillionBytes
Enoughspace
tostore
hundredsof
highresolutionphotos
iPadstoragecapacities
rangefrom
16GBto 256GB
USBMemorystick
storagecapacities
rangefrom
8GBto 256GB
Whenpurchasing,lookoutfor
U3B3.0devices.
U3B3.0 transferspeedsare10timesfaster.
Thatbecomesimportant
whenyoustarttomove
Gigabytesofdata.
Portableharddisk
storagecapacities
rangefrom
500GBto4TB
ATerabyteis1000Gigabytes
Enoughspacetoholdanenormous
collectionofmusic,books,andphotos.
Again,whenpurchasing,lookoutforUSB3.0devices.
ThefirstiPad
wasreleasedin2010.
GraphofCPUTransistorCountAgainstTime
Transistorcountswillcontinueto
doubleattwo-yearintervals
forthenexttwentytofortyyears...
Thefirstmodels
arenowobsolete,
fortheirchipsetslackthe
input/outputfeatures,the
RAMandtheprocessorspeed
requiredtohandlethelatest
operatingsystems.
?
…and
perhaps
for
thenext
600years.
TheiPadPro,releasedinNov2015,hasupto256GBofstoragememory,
a2.24GHz64-bitDualCoreA9Xprocessorand4GBofRAM.
Ittookrailwaytechnologyover200yearstodevelopbullettrains.
Digitaltechnologydevelopmentbeganinourlife-times
andisproceedingfarmorerapidly.
Newerdigitaldevicesaremuchmorecapablethanolderdevices.In
thecaseofiPads,forexample:
• ThemorememoryaniPadhas,themoreaudiotracks,booksand
photositcanstore.
MemorycapacityisspecifiedinMegabytes,Gigabytesand
Terabytes(Millions,BillionsandTrillionsofBytes).
• ThefasteraniPad’sclockcantickandthemoreprocessorcoresit
has,themoreresponsiveitbecomes—thequickeritcanrespond
toscreengestures,startapplications,displaydata andmovedata
toandfrommemoryandtoandfromtheinput/output(I/O)
ports,etc…
Clockspeeds arespecifiedinMegaHertz andGigaHertz (Millions
andBillionsofcyclespersecond).
That’senoughabout
thebinarynatureof
digitalaudio,booksandphotos,
thememoryspacetheyoccupy
andprocessorspeeds.
Itstimetomovesomedata
intoaniPad.
Let’sstartwithMusic.