Specifications

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PCMCIA
Expanding Portable Systems
Founded in 1990, the Personal Computer Memory Card
International Association (PCMCIA), of which Quatech is a
member, developed a set of standards by which additional memory
could be added to portable systems. It soon became apparent
that this same interface could be used to add I/O devices and
hard disk drives as well, thereby dramatically increasing
functionality of laptop computers. Today, just about any device
available for desktop computers using an ISA or PCI bus is also
available with a "PC-Card" interface for use with laptop computers,
and in some cases, hand-held machines.
Physical Characteristics
The PCMCIA specification 2.0 release in 1991 added protocols
for I/O devices and hard disks. The 2.1 release in 1993 refined
these specifications and is the standard around which most
PCMCIA cards are built today.
PCMCIA cards are credit card size adapters which fit into PCMCIA
slots found in most hand-held and laptop computers. In order
to fit into these small size drives, PCMCIA cards must meet very
strict physical requirements as shown in the chart below. There
are three types of PCMCIA cards, Type I generally used for memory
cards such as FLASH and STATIC RAM; Type II used for I/O
peripherals such as serial adapters, parallel adapters, and fax-
modems (this is the type of card Quatech manufactures); and
Type III which are typically used for rotating media such as hard
disks. The only difference in the physical specification for these
cards is thickness.
Card & Socket Services
Functionally, a PCMCIA card can perform any memory or I/O
operation as long as it adheres to the PCMCIA interface structure.
As shown in the above diagram, PCMCIA is a tiered system that
uses a set of device independent drivers to integrate any type of
PCMCIA card into the host system. Socket Services, the lowest
tier in the architecture, provides a universal software interface for
the PCMCIA sockets themselves. Socket Services manages all the
sockets installed in a system so that resources can be properly
allocated. It is also the means by which individual cards access
registers on the host system. Socket Services can be added to a
computer as a device driver, or it can be built into the PC BIOS.
Directly above Socket Services in the hierarchy sits Card Services.
Card Services is an application programming interface (API) that
permits multiple software programs to work with multiple PCMCIA
cards. For instance, Card Services will allow both internet
applications and fax applications to use an installed PCMCIA card
modem. Like Socket Services, Card Services can be implemented
as a device driver, and can be built into a computer's operating
system, as it is in Windows 95/98/Me/NT/2000 and OS/2.
16-Bit PCMCIA
PCMCIA specification 2.1 provides for a 16-bit bus interface, has
a maximum clock speed of 10MHz and is capable of speeds to
Interface: 68 pins
I/O Connection: manufacturer determined
Length: 85.6 mm
Width: 54.0 mm
Thickness: Type I 3.3mm
Type II 5.0 mm
Type III 10.5 mm
Substrate Area
Type I--3.3mm thick
Type II--5.0mm thick
Type III--10.5 mm thick
Interconnect Area
68-Pin Connector
85.6 mm
54.0 mm
Operating Temp: 0 to 55
o
C
Storage Temp: -20 to 65
o
C
(PCMCIA Card Physical Characteristics)
Operating
System
BIOS
Flash File System
PCMCIA
Drive
connector to host
68 Pin Socket
68 Pin Connector
PCMCIA
Card
Memory
Technology
Driver
Application Software
(Block Diagram of a Basic PCMCIA Expansion System)
host
Card
Services
Socket
Services
Memory
Card
Device
Driver
PCMCIA