External components of a Mac or a PC
The different external components are:
Input peripherals
Keyboard
Mouse
Trackpad
Trackball
Graphic tablet
Touch screen
Scanner
Audio/Video input card
...
Output peripherals
Video display
Printer
Fax modem
Network interface
External storage
Hard disks
Removable storage devices
Floppies and similar storage devices
Flash drives
CD/DVD burners
...
External connectors
Input peripherals: 
They are used to input information: keyboard (text
input), scanner or camera (image input), microphone (sound
input).
Keyboards 
Due to the lack of direct vocal encoding, the keyboard is
THE input device for text.

The best of the keyboards: 10 years of hard working
before death ;-)
This an Apple pro keyboard: more than 300 euros ten years
ago.
Two ADB connectors: one on the left, one on the right ->
we can put the mouse where we want!

The worst ADB Apple has never produced: awfull key
rendering, noisy, ADB connector on the rear... :-(

USB keyboard of the early iMacs: connectors on left and
right... back to user friendly design :-)

The transparent PRO one: big function keys... but very
quickly dirty.

A Macally keyboard. Very good.
And now, one can find wireless keyboards or one can use
USB PC keyboards.
Mouses 

From left to right: a MacPlus mouse, one of the last
Aplle ADB mouse, the first Apple USB mouse and the Apple
basic optical mouse.
If you have to change your mouse, I would suggest the
optical choice... but not the Apple one.
Optical because no wheel, no dust...
Not Apple because the Apple one is expensive, delicate, has
a very short cable..and only one button.
For instance Logitech brand mouses are very good...

... here it is.
The "plus": light, optical, long cable, 3 buttons (avoid to
use CTRL-click to bring up the contextual menu), a wheel
(for text scrolling)... and around 20 euros.
One can alos find wireless mouses. Either optical one
(infrared) or Bluetooth based (radio frequency).
In both cases, the mouse must analyze signal it receives
-> the mouse must be powered: batteries (rechargeable or
not).

A USB trackball.

A USB graphic tablet. Many people who has one does not
use the pen... and are happy: (1) not have a wire to the
mouse and (2) not be forced to use batteries!
Scanner
This peripheral is used to scan a image lied down on a
glass and memorises it in the computer.
The image can therefore be manipulated by special tools: for
instance a photo manipulation software or a software being
able to extract text from an image (OCR).
In the past, they had a SCSI connector. Now they use USB
or Firewire.
Several points can help to select a scanner to buy:
[1] Its resolution.
The higher it is, the easier the scanner will have to zoom
parts of the image you want to import. It is important to
pay attention to the scanner's real resolution: sometimes,
salesmen speak about an (computed) interpolated resolution.
The scanner computes new points to artificially increase its
resolution (for zomming for instance) but the more it does
that, the lower is the quality of the result.
[2] Next point is the scanner's abilty to take the
high and low lights into account.
Audio/Video input devices 
Such devices help you to enter images/fims or sound form
several sources (TV, camera, ..) into the computer.
Either they are "pro" (and therefore expensive), either they
have a limited use (home use) and they cannot handle a huge
amount of data.
Output peripherals: 
They allow to extract information from the computer and
send it on the screen, on a printer, on a fax, on a modem or
a network.
Video displays
At the very beginning, Apple use a proprietray DB 15
connector system which forces mac lovers to pay expensive
prices for display monitors. For instance, in '91, a 13''
display monitor cost 800 euros. i.e. the actual price of a
low end eMac !
Then next, Steve starts to think... -> the VGA
connector, the same as the Empire has, is used on Mac. More,
the DVI one is also used: this Digital Video Interface
transmits numerical signal and not analogic one!
Then, Apple comes back to its bad "proprietray" pratices:
the ADC strikes back -> so to connect a modern display
monitor to a (?modern?) Mac, we have to insert a DVI ->
ADC adapter (150 euros).
ADC = DVI + power wire in the same cable...the big
disavantage is to require special graphic cards... which, on
Macs, cost twice the price of the equivalent graphic card on
PC... just for a different ROM !
-> So, before using a new monitor, check the
connectors!
Fortunately, on modern Apple monitors, standard DVI
connectors come
back !
Printers 
Printers were first connected through a serial cable
(mini-din 8) or through a LocalTalk network. With iMacs,
arrives the USB standard...while the ethernet was still
wisdzly used;-). Once upon a time, on Mac machines, one cwas
able to use infrared connection to print, but now this type
of connection has disappeared: Bluetooth connection is the
"up-to-date" fashion.
We have inkjet or laser printers:
1. Inkjet printers are cheaper..but cartridges are
expensive.
2. Laser printers are more expensive to buy (especially
color laser) but are less expensive to use. Unfortunately,
colors laser printers commonly over saturate the colors.
Modem/fax 
In the past, they were external devices, connected on the
serial port and expensives (let's say, 8 years ago, 250
euros for a 14.400 bauds modem... 4 times slower than the
standard RTC modem you can fine in iMacs). Now, all of the
modems are connected to the USB: either they are really USB
ones, either they need a USB to serial adapter.
To send a fax, you need a modem but also a standard phone
line: fax cannot be sent through a DSL or cable modem!
Network interfaces 
Always, the Mac was a communicating machine. First we
have AppleTalk protocol in a localtalk network: easy but not
quick, one can share files or printers.
Then come network cards, first in BNV with coaxial
cables.
This system is based on a token ring. Main disavantage, if
transmissions in cable are interrupted, the network is down
:-(
Then the base-10 RJ-45 , followed by the base-100 and
base-1000 network.
A star based network with a hub/concentrator in the center:
if one machine has a problem, other ones are not affected.
Now, we have wireless networks: with airport 802.11b (11
Mbps in theory..6 in pratice !) and airport extreme 802.11g
(54 Mbps in theory... 30 in reality !). They are based on
radio frequencies in the range of the 2.4 GHz. Machines in a
radius of 300 meters can be connected to the same station.
There is also the Bluetooth system (1 Mbps in theory) but
not so far network minded: more for cellular phones,
peripherals (printers,..), ...
And now Apple is focusing its attention onto FW-based
networks.
External storage 
To store data for backup, exchange data from one machine
to another or simply to have an extra capacity.
Hard disks
Short
description. There are 3 types of external hard disks:
SCSI: very expensive.
FW: 400 and 800 (around 30 Mo/s).
USB: USB2 (60 Mo/s in theory; 15 Mo/s in reality) and USB 1
(1 Mo/s; too slow; forget it as far as external disks are
concerned).
Note that, in general, USB & FW external drives are
not totally USB & FW but contain a EIDE-> USB/FW
internal bridge !

4 types of external disks: from top to bottom: an 2.5''
in a FW box, a 3.5 '' EIDE in a FW/USB1 box, an SSCI one in
a powered box and finally anothe SCSI disk.

Face view. About capacity:
- 10 gigas
- 60 gigas
- 1 giga
- 500 megas

- FW (firewire)
- USB 1
- SCSI 50 pins
- power conector
- ON/OFF switch
- SCSI terminator
- SCSI Id selector
Removable storage devices 

The most commonly used removable storage devices (tapes
drives, less used for domestical purposes, are not shown):
- Floppy: here an HD (1.4 Mb); before floppies were 5''
flexible supports; no longer used since iMacs!
- ZIP(Tm) (100 Mb, 250 Mb): "supper" floppies; delicate
and flexible.
- Magneto-optical cartridge: sure, big capacity but
slow; for backup purposes; same as actual CD-RW.
- SYQUEST(Tm) (44, 88 and 200 M); a hard disk plateau
within
an cartridge!
- JAZZ(Tm) (1 or 2 G).
The only removable storage devices which has survived is
the ZIP... despite all its weaknesses.

Compact Flash USB reader (with a 64 Mb card). That's the
tendency of the moment: FLASH memories within keys,
cards,... 32/64/428/256/512 M are common; 1 G are still
expensive.
I would prefer the card+reader choice: less expensive,
reader is faster, you can use the card directly in modern
PCs or laptops... not in Macs!
No mechanics inside -> more resistant, less
cumbersome... but more expensive.
CD and DVD 
The most widely used storage support is the CD-R. 700 Mb
on it, quick to burn (modern burners run at 52 X) and all
the actual machines have one.
-> the solution for transfering data (files, music,
games,... ).
Bigger is the DVD (4,7 gigas). Unfortunately, the big
problem of the DVDs is the disparity of their formats.
Most of the Macs must use/burn DVD-R, PCs use/burn
DVD+R.
Some Macs can read DVD+R, but cannot burn them (except when
the burner is "flashed").
Now, double layers DVDs are on the market but with no
standard at all.
Newest G5 superdrive cannot handle such DVD, recent PCs
built-in burners are compatible !
Double layers DVD are dedicated to store a huge amount of
data (more than 8 Gb) and are sepcially dedicated for video
films. But unfortunately, such burned DVD cannot be read in
most of the living-room DVD players !
Modern burners are now of the USB2 and FW types.
In the past, they were SCSI: 500 euros for a 4X CD-R
burner. Yes. Really ;-).
Then next, they were USB1 for the early iMacs... but run
away of these so slow (1X in the better cases) machines :-(.
External connectors 

Rear face of G4:
- 2 firewire ports
- one RJ-45 (ethernet)
- 2 usb ones
- sound input
- sound output
- RJ-11 modem port
- VGA port
- DVI port
- an PCI card's SCSI port

Rear face of a G3:
- Display monitor's power plug
- The machine's power plug
- SCSI 1 original port
- The ADB port to connect a keyboard/mouse/graphic
tablet... and some modems which, beside being very slow,
also were powered through this port!
- RJ-45 network standard connector
- Min-din 9 ports (also called "geoport"): to connect
mdeom/printer or a localtalk network
- DB-15 Apple proprietary connector welded on the
motherboard
- Standard input sound device
- Cinch input/output and video composite
connectors
- In and Out S-video ports
- A USB PCI card
- A FW/USB PCI Card

Titanium rear side:
- Power plug
- FW port
- RJ-45 ethernet port
- Two USB ports
- A DVI port
- one S-Video port
- ?
- The modem port

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