2.0 Laptop and Portable Devices
2.1 Identify the fundamental principles of using laptops and
Expansion slots (e.g. PCMCIA I, II and III, card and
All PC cards use same connecting interface with 68 pins. All are 85.6 mm long
and 54.0 mm wide.
The original standard was defined for both 5 volt and 3.3 volt cards. The 3.3
V cards have a key on the side to protect them from being damaged by being put
into a 5 V-only slot. Some cards and some slots operate at both voltages as
Type I: These cards are 3.3 mm thick. They are primarily used for
adding RAM ROM to a notebook PC. They accommodate 16-bit interface.
Type II: These cards are 5.0 mm thick. These cards are often used for modem,
fax, SCSI, and LAN cards.
The Type III: Type III cards are 10.5mm thick, sufficiently large for
portable disk drives.They can also accommodate interface cards with full-size
connectors that do not require dongles (as is commonly required with type II
Differences between PC card slots
As with the physical PC cards, PC slots also come in three sizes:
A type I slot can hold one type I card
A type II slot can hold one type II card, or two type I cards
A type III slot can hold one type III card, or a type I and type II card.
Most notebook computer systems come with two PC card slots that allow for the
use of two type I or type II PC cards and one type III PC card. The PC card
slots are stacked with one above the other. Usually, type III PC cards fit only
in the bottom slot.
The older PC card standard was 16 bits at 8MHz. Cardbus is an extension of
the PCMCIA standard, which expands the bus bandwidth and throughput to 32 bits
at 33MHz.. PCMCIA card version 5 and above comply with Cardbus standard. Cardbus
is analogous to the PCI slots in desktops, while the older PC card standard is
analogous to ISA. The newer cardbus slot can accommodate an older 16-bit PC
card, but it doesn't work other way round.
ExpressCard is being built on the USB 2.0 and PCI Express buses. It increases
speed and reduces the cost and complexity of the PCM bus. The complexity is
eliminated by doing away with the PCMCIA Host Controller. ExpressCard has a
direct connection to the system bus over a PCI Express x1 lane or USB 2.0. ,
whereas CardBus utilizes an interface controller to interface with PCI. The
ExpressCard has a maximum throughput of 2.5 Gbit/s through PCI Express or 480
Mbit/s through USB 2.0 dedicated for each slot, versus CardBus's shared 1066