PCMCIA: The New Peripheral Standard
by Wayne Yacco

as appears in Issue #14, Sept/Oct 1993 PEN Magazine
copyright (c) 1993 PenWorld, Inc.
Call (800) 383-PENS, fax (310) 377-8218 or email 71333,124 for 
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	The original desktop computers distributed control of 
computing intelligence to the local user.  So, they were dubbed 
personal computers.  When compared to the centralized mainframes 
and minicomputers that preceded them, they were.  Personal digital 
assistants, personal mobile communicators, and hand-held computers 
take the idea of personal computing to another plateau.
	It's too bad "PC" has been co-opted by that earlier usage.  The 
terms that have been proposed as alternatives to "PC" just don't 
work.  Personal digital assistant, for example, smacks of redundancy-
-unless you expect analog versions to appear.  It's too long and 
awkward too.  We need a term with immediacy--something like 
intimate computer.  It's a good choice for several reasons.  It's short.  
It conveys the ever-so-close relationship of a machine you write and 
draw into, message with, and then stick in a pocket.  And it's 
abbreviation, IC, already designates the large complex chip into 
which all of this functionality is quickly converging.  Watch out, Dick 
Tracy, you'll be talking, and computing, into your lapel pin soon.  
Eventually, there will be the ultimate IC, the integral computer that's 
surgically implanted into your grandchildren just before they're old 
enough to verbally command it.
	This column is about the very next step on the way to that final 
down-sizing: the PCMCIA (Personal Computer Memory Card 
International Association) card.  PC Cards bring the functionality of 
their full-size ISA, EISA, and MCA counterparts down to so few chips 
that they can easily move between your wallet and your intimate 
computer.  They're called PC Cards, but they are IC cards in every 
sense.
 	PCMCIA began only a few months ago as a way to interface 
storage cards, but has quickly evolved into a new bus specification 
for credit-card-sized peripherals.  With it's support for I/O, the new 
PCMCIA, version 2, specification can open the smallest machine to 
add-ons of all kinds.  Cards provide communications, connectivity, 
interfaces, both solid-state and rotating storage, a host of memory 
devices (flash, one-time-programmable, and static), and a rich 
variety of other options.  It's the stuff that enables a general-purpose 
computer to support all manner of vertical niches.  PCMCIA examples 
already include products like Proxim's RangeLAN, a spread-spectrum 
wireless network adapter.  Toshiba is shipping a card that encrypts 
data, and makes access to it impossible without a password.  Toshiba, 
and a few other vendors, are also shipping a SCSI adapter on a 
PCMCIA card.  Competition among the many vendors shipping 
memory, modem, and network-adapter cards is brisk.  Modem-
maker Megahertz is already making one that's completely self-
contained.  Consider that most pen-based machines are presently 
employed in vertical applications, and it's easy to see that PCMCIA is 
the spark that's going to fire up those markets.
	The time is definitely right.  Cards designed for the current 
spec are increasingly compatible with new machines.  This has come 
about, in part, from new hardware glue: the Intel 80365, the 
Databook DB86082, and similar ExCA interface controllers from 
several others.  ExCA is a functional spec--not a register-level 
interface--for which Intel, Databook, and others have successfully 
completed the Socket Compatibility Test..  Whichever glue chips a 
host manufacturer chooses, all provide conformance to the PCMCIA 
spec in a module the vendor can easily plug into computer designs.
	Software for the chips may be supplied by the silicon foundry:  
Databook supplies all the necessary code.  Or it may be supplied by 
third parties as is Intel's Card Services software.  This is important, 
because in some early implementations, host vendors haven't always 
written their code according to the PCMCIA spec.  In the name of 
expediency, they have sometimes employed hardware-dependent 
code.
	Megahertz vice president Steve Aldous recalls when the first 
Intel modem cards landed on shelves.  Since it was then the only 
card on the market, he says, some machines were built around its 
silicon.  "Gross violations of PCMCIA rules resulted," maintains 
Aldous.  Some systems actually looked for the Intel name in a chip, 
and wouldn't enable the card if they didn't find it.  The Toshiba 
T3300 gave Megahertz difficulties, because it expected a card to 
decode all the address lines, as Intel does, and wouldn't allow the 
PCMCIA-approved alternative of using a select line.
	PC Card LAN adapters, which typically require the end user to 
configure the card and socket with an "enabler" program, are another 
example.  A few enablers still talk directly to the controller's 
registers instead of to PCMCIA interfaces.  Fortunately, the industry 
is rapidly moving away from such dependence by following new 
specs called Card Services (CS) and Socket Services (SS).  "The 
chances of plug-and-play today are much higher than they were a 
year ago, even six months ago," Aldous says.
	Card and Socket Services provide specifications to which 
drivers can be written.  Tom Mitchell, National Sales Manager for 
Proxim says, "We take advantage of Card and Socket Services to 
expand our compatibility with different products."  Not all card 
vendors do though.  Some fail to provide complete information in the 
on-card Card Information Structure (CIS) header which is supposed 
to identify the card's requirements.  When information is incomplete, 
hosts may still be able to support many PCMCIA compliant cards 
with a common driver by detecting the card and filling in the missing 
information.  For example, hosts are able to support fax-data modem 
PC Cards which employ the Hayes modem interface or other popular 
models with well-known requirements. 
	Unknown cards can also be handled another way, under the 
new specification, by allowing drivers stored on the cards themselves 
to be downloaded by the host.  If card makers adopt the practice of 
storing drivers on their products, it can altogether eliminate the need 
for hosts to recognize them, or to supply users with loadable driver 
software.  However, this solution requires a complete PCMCIA 
software package, and complete implementations are only now 
coming to market.
	Not all card vendors have yet adopted fully successful 
strategies.  Mitchell admits that Proxim occasionally has run into 
minor glitches that have had to be worked out with its host-side 
partners.  However, Mitchell credits the specification for keeping the 
process simple enough to work out the details over the phone.  "The 
problems that we've seen have been easy to conquer," he says.
	Daniel Sternglass, Databook chairman, a member of the PCMCIA 
board, and chairman of its Host Compatibility subcommittee, 
cautions: "Machines that claim PCMCIA compatibility may not have 
Socket Services or Card Services, because there are not yet PCMCIA-
sanctioned compliance criteria."  Yet, by using recognition techniques 
and generic-card handling, he says that many of these systems still 
handle a wide range of cards.  Sternglass recommends shopping for 
host systems based on PCMCIA software that includes Card and 
Socket Services, and that come from a reputable supplier.  
Regrettably, compliance is not easily detectable by end users.  On the 
positive side, CS is upgradeable.  SS may be, too, if the machine's 
BIOS is.  SS code can even be stored on a hard disk, and run from 
RAM, when it's not required to boot the machine.
	While vendors work these issues out for themselves, PCMCIA 
continues its shake-down cruise.  Luckily, PCMCIA compatibility is 
accelerating faster than the evolutions that produced standard 
emulations of the IBM PC BIOS for systems, the Hayes AT-command 
language for modems, and the H-P Printer Command Language (PCL) 
for printers.  In fact, PCMCIA already seems more compatible than 
SCSI, which still requires installable drivers for every machine, and 
sometimes even requires different removable media--even on 
identical hardware when its sold under different brands.  PCMCIA 
should soon reach the relatively trouble-free state of such successful 
standards as PostScript and Ethernet.  When the final bugs are 
worked out, survivors among the early participants will reap large 
rewards.  Survivors?  You know what they say about pioneers.  
They're the ones with the pointy ISO flowchart symbols for off-page 
connections in their backs.
	PCMCIA still has a nagging complication in the difference 
between compliance to the specification and implementation of it.  
For example, not all machines supply both five and twelve volts.  
And there's a limit to the current that smaller machines can supply.  
Some machines will always be designed for applications that don't 
call for a full implementation, and not every system will be able to 
program flash memory or run a hard disk.  Thus, not all cards are 
going to work with all machines--even when the card conforms to all 
parts of the specification.
	Nevertheless, it does seem that most compatibility issues have 
been resolved, or are resolvable.  I'll monitor PCMCIA's progress by 
conducting practical compatibility trials and reporting the results in 
this column.  Next issue, I'll continue this column with thumbnail 
reviews of several cards that, if not exactly unique, are at least 
representative of less-common offerings.  It will include those I've 
already mentioned, plus one or two others.  And I'll have a 
comparison table of many additional PCMCIA products.

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