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Vadem/Amphus White Paper: A Superior PC Card Socket Controller for
Desktop Systems
Document No. WP-000038-01
Information furnished by Vadem/Amphus is believed to be accurate
and reliable. However, no responsibility is assumed by Vadem/Amphus
for its use; nor for any infringements of patents or other
rights of third parties which may result from its use. No
license is granted by implication or otherwise under any patent
or patent rights of Vadem/Amphus. Vadem/Amphus reserves the right to change
specifications at any time without notice.
Trademarks mentioned herein belong to their respective companies.
Medical Disclaimer
Vadem/Amphuss products are not authorized for use in life
support devices or systems or in any medical applications
and cannot be used in such applications without the written
consent of the President of Vadem/Amphus.
Introduction
Personal computers have revolutionized the way people
work. Today, PCs are used in a wide range of settings and
have become a primary business tool. With these innovations,
however, have come new industry challenges. Configuring PC
hardware and operating systems to work with different peripheral
devices can be a significant problem. Changing the hardware
configuration of a machine is a task few end-users attempt,
and even trained technicians can find configuration to be
difficult, time-consuming, and frustrating.
A broad base of companies within the computer industry, however,
is addressing these problems with a technology known as plug-and-play
(PnP), which gives consumers the ability to add or remove
hardware in PC systems without worrying about switch settings
or hardware conflicts. This technology was originally designed
for the PC Card industry but has since effectively migrated
to the desktop platform. Most of the PC add-on cards now come
with the PnP feature, and naturally, the ISA host adapters
for the PC Card socket controller have to support this technology
as well.
This paper reviews some key issues of integrating the PC Card
socket controller into the desktop computer. It also discusses
solutions Vadem/Amphus provides for PC Card support in a desktop
system.
Executive Summary
As a larger number of PC Card-based products have become
available, more desktop systems are now equipped with PC Card
slots. As a result, demand for PC Card Socket Controllers
is also growing.
Vadem/Amphus has designed a full line of PC Card Socket controllers
to fill the increasing need for interfacing PC Cards to the
host. Vadem/Amphuss product line ranges from the fully featured
VG-469 controller to those for use in space-limited and cost-sensitive
applications.
Vadem/Amphuss VG-469 PC Socket controller has the following
features:
- 82365SL
compatibility
- Mixed
voltage support (for both 5 V and 3.3 V card and host systems)
- PC
Card DMA
- ISA
bus Plug-and-Play
- Driver
for activity LED indicator
- Low-voltage
card protection
- Control
signals for buffered cable
The VG-469 is a plug-and-play solution, which eliminates the
need to configure jumpers or change switch settings to the
host adapters. Other features, such as hot insertion and very
low power consumption make Vadem/Amphuss PC Card Socket controllers
an excellent choice for todays platforms with PC Card
access.
PC Card and Desktop PC
PC Card (formerly PCMCIA) was designed to provide resources
that users could add to and remove from a system without rebooting
or turning off the host. PC Card technology not only offers
the users a simple way to add more memory or additional peripherals
to a machine, but also provides a convenient means for resource
sharing among systems. Another benefit of the technology is
that it gives users a quick way of safeguarding data, which
improves system security.
The market for PC Cards has been expanding rapidly, and the
PC Card industry forecast continues to be healthy. According
to Andrew Prophet Research and Consulting, over 4.5 million
PCs shipped in 1995 contained at least one PC Card slot. In
1999, just three years from now, the total number of platforms
shipped will be in exceed of 29 million. On the card side,
by the end of this year, over 20 million PC cards will be
shipped, and in 1997 that number will be well over 33 million.
Furthermore, the Department of Defenses recent decision
to make PC Card slot a necessity for all their PC procurements
will further promote the growth of this market.
Although the driving force behind the PC Card has been the
portable industry, the trend is changing. More desktop systems
now are equipped with PC Card slots. The reason is that there
is a large number of PC Card-based products now available.
Some of the peripheral devices currently available are: Hard
Drives, CD-ROM Interface, Docking Station, Data Acquisition
Devices, Memory Cards and Video Capture Cards. And the fact
that desktop users dont need to open up their systems
to install and configure a new piece of hardware is very appealing.
The hardware that establishes the interface between the PCMCIA
bus and the host bus is called PC Card Socket Controller
and is usually implemented in a stand-alone IC or with other
functions in a system. Different silicon vendors provide different
solutions for this component.
Vadem/Amphuss PC Card Socket Controller Solution
Vadem/Amphuss VG-469 is a fully-featured, Intel 82365SL-compatible,
socket controller. The VG-469 directly supports two sockets
with hot-insertion. For systems requiring more than two sockets,
VG-469s can be cascaded to support up to four sockets with
no glue logic. For larger systems, any number of these controllers
can be cascaded with minimal external logic. Besides supporting
mixed voltage cards, the controller can operate in both 5V
and 3.3V host systems. Other features include PC Card DMA,
ISA bus Plug-and-Play, a driver for an activity LED indicator,
low-voltage card protection, and control signals for different
buffered cable schemes. The VG-469 controller is perfectly
suited for desktop systems.
Plug-and-Play (PnP) Support:
Most desktop PCs dont come with a built-in PC Card
interface on the mother board. To add this capability to the
system, end-users usually go with the add-on board solution.
The notorious inconveniences during system configuration (such
as I/O port allocation, interrupt request assignment, DMA
channels, and address ranges) are sometimes troublesome. The
reason for this problem is that the added hardware usually
has jumpers or switches for setting up the parameters mentioned.
Once configured, the jumpers not easily changed on-the-fly.
In a typical situation, an incorrect jumper setting makes
the add-on card non-functional. In a more severe case, the
set-up conflicts among different hardware may hang the system.
Unlike most of the ISA socket controllers on the market that
possess the annoying problem of resource allocation conflict,
the VG-469 has solved this problem with its integrated plug-and-play
capability.
To alleviate the irritating resource conflict issue, the Plug-and-Play
ISA Specification provides a mechanism to automatically configure
any ISA card on the bus. In general, the PnP system executes
the following steps in the process of auto-configuration:
- Isolate
the card
- Read
the cards resource data
- Identify
the card and configure its resource
- Locate
a driver for the card.
From the hardware standpoint, the plug-and-play specification
defines a set of configuration registers located at pre-defined
I/O addresses that all PnP devices must implement. The PnP
software accesses these registers in the resource allocation
process. When a card is identified, either by the BIOS (in
a PnP compatible BIOS system) or by the operating system (in
a non-PnP BIOS system), the card sends the device ID to the
operating system. The operating system then uses the device
ID to access the correct driver for the card.
The plug-and-play function integrated into Windows 95 supports
a wide variety of devices. Vadem/Amphuss VG-469 PC Card socket
controller is one of the supported devices. Configuration
information stored in a serial EEPROM allows the host to find
the appropriate software driver for the VG-469.
This information is then used to find the PnP driver for the
VG-469. Once the driver has loaded, the VG-469 system is configured
and the socket is ready to communicate with the PC Card. The
configuration process described above is fully automatic.
There is no user-required input. This simplicity cannot be
achieved on a system without a plug-and-play PC Card socket
controller. In a non-PnP socket controller system, there are
usually multiple jumpers or switches that must be verified
or changed. On a highly populated desktop PC, this manual
configuration is even more of a problem.
In conclusion, the plug-and-play feature allows flexibility
of resource allocation in any type of system. With plug-and-play
ISA support, desktop PCs with either one or multiple controllers
can automatically relocate the socket controllers to any available
address. PnP also benefits notebook systems with docking stations.
PC Card and PCI bus
Currently, PC Card software drivers do not support PCIs
interrupt structure. Existing PC Card socket controllers interfacing
with the PCI bus generally carry sideband ISA interrupt signals
that must plug into an ISA slot. This solution is clearly
not desirable. To remain compatible with the vast number of
existing PC Card socket controllers on the ISA bus, client
drivers are not likely to change. As a result, a PC Card socket
controller on the ISA bus is still the best solution.
Compatibility
The PCMCIA group has produced a well-defined specification
for the PC Card adapter, but has not defined a standard architecture
for the socket controller. Because of that, various design
approaches have been employed by various silicon vendors,
which may cause support problems for software developers.
Intel Corporation introduced the first socket controller (82365SL),
which was designed for the ISA bus. The 82365SL has been very
well-supported by software driver vendors. Recognizing the
wide support of the 82365SL, Vadem/Amphus has made the VG-469 upward-compatible
with the 82365SL register set, which helps minimize software
driver development time, reducing product time to market.
The Exchangeable Card Architecture Specification (ExCA) has
further helped the socket controller industry to somewhat
standardize controller architecture. For instance, the ExCA
specification requires that the PC Cards memory and
I/O address space map directly into the CPUs memory
and I/O space, respectively. Register-based socket controllers
cannot comply with this requirement. Also, according to ExCA,
a minimum of five memory windows addressable in 4K blocks
on 4K boundaries or a minimum of two I/O windows located on
1-, 8-, 16-, or 32-byte boundaries must be allowed. Furthermore,
the ExCA specification recommends that the interrupt from
the PC Card be steered to any one of the 10 IRQs on the ISA
bus.
Note that not all socket controllers available on the market
meet all these requirements. Again, the VG-469 and all other
socket controllers designed by Vadem/Amphus are fully compliant
with this specification, preserving your
investment.
Card Protection
The PC Card standard (version 2.1) requires
mixed-voltage operationthe socket must provide 5 volts,
3.3 volts, or even lower voltages to the card. This versatility
obviously requires some mechanism to prevent a 3.3-volt card
from being damaged by a 5-volt supply. To avoid this problem,
the PC Card specification recommends the use of a keyed connector
for the socket. However, a keyed connector alone cannot always
guarantee protection of a low-voltage card, since an incorrect
driver or even a software glitch may inadvertently command
the socket controller to send 5-volt power to a 3.3-volt card.
The VG-469 has a voltage-limit feature that protects a 3.3-volt
card from being powered by a 5-volt supply from the socket.
This feature is very important for a desktop system because
most desktop PCs operate at 5 volts, while many PC cards are
designed for a lower voltage environment.
Cable Buffering
Most of the PC Card hard drives for desktop PCs consist
of two physical cardsone plugged into the ISA bus on
the mother board, and the other mounted in the drive bay.
These cards are generally connected together by ribbon cables.
Different designs may have different schemes for the ribbon
cable connection. For the design that places the socket controller
IC on the ISA interface board, all the PC Card signals have
to route to the appropriate socket. In a single-socket drive
system, 68 signals need to be sent over the cable, usually
requiring two 40-pin ribbon cables. In the dual-socket drive
bay design, the number of signals is, of course, doubled.
Because of signal quality concerns, these signals are usually
buffered before transmitting to the ribbon cable.
The Vadem/Amphus VG-469 chip provides control signals for different
buffered cable methods. The control signals can be programmed
for controlling the buffers located on the ISA bus or, alternatively,
they can be programmed to control the buffers that are positioned
on the drive bay. With this feature, the system designers
save glue logic for controlling the signal buffers.
Other features
If power consumption is a concern, the Vadem/Amphus socket controllers
are certainly the best choice. In addition to a low internal
operating clock, all Vadem/Amphus chips include an activity timer
that can be programmed to further reduce the power consumption
of the part. In power down mode, with all inputs static, the
VG-469 controller consumes only 10 microamperes.
Another critical requirement for the PC Card interface is
hot insertion (the ability to insert and remove
the card without powering-down the system). Hot insertion
is usually implemented with several buffers and transceivers.
The VG-469 contains these components on-board, which further
reduces the design cost.
Besides their superior design, Vadem/Amphuss PC Card socket
controllers are also supported by many major driver vendors.
Vadem/Amphus can also provide several proven reference designs to
customers for fast time-to-market designs.
Competitor offering
Very few 82365SL-compatible PC Card socket controller
vendors have the plug-and-play feature built into their products.
The DB86184 chip (made by Databook) has plug-and-play feature,
but this chip is not 82365SL and ExCA compatible. And the
power consumption of the DB86184 is about 40 MA in standby
mode compared to 10 microamperes for the VG-469.
All Vadem/Amphuss socket controllers are compliant with PCMCIA
2.1/ExCA and JEIDA 4.1, and fully register-compatible with
Intel 82365SL.
Summary
With continuing cooperation among the numerous members
of the PCMCIA group, the future of the PC Card industry will
certainly look better. As demand for PC Card grows, the system
designer has little choice but to supply more platforms with
PC Card access. To ensure smooth operation between the card
vendors and the platform producers, designers must be very
careful in selecting socket controllers. The most important
factor in choosing the right controllers is, of course, adhering
to industry standards. While this is true, the designers using
PC Card socket controllers should also look beyond the basic
characteristics of the PC Card standard, because features
such as plug-and-play, protection for low-voltage cards, and
advanced power management are no doubt very desirable to end
users.
While many socket controller vendors have done a good job
in meeting industry standards, only Vadem/Amphus has managed to
produce a PC Card socket controller that satisfies all the
above requirements.
Vadem/Amphus Corporation, 1960 Zanker Rd., San Jose, CA. 95112
Phone
408.467.2100 FAX 408.467.2198
Copyright © 1998-2003 Vadem/Amphus
All Rights Reserved
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