Because of the widespread use of digital cameras, PDAs, laptops, and other portable electronic devices, most companies, and even consumers, have reached the point of wanting to standardize on a single type of expansion port. Since the majority of add-ons purchased are memory expansions, in this Daily Drill Down I’ll focus on the four most available formats currently on the market: CompactFlash, MultiMedia Cards, Smart Media, and the Sony Memory Stick. Each is used in a variety of products and is readily connectable to PC and Mac desktops and laptops. These memory expansion cards have developed in a surprising direction. By including special circuitry, they’ve also become device interfaces.

What is flash memory?
Flash memory is solid-state data storage using semiconductor chip technology. It is nonvolatile, meaning that data is stored indefinitely without a power source. It requires very little power to operate and has no moving parts to wear out. While older flash devices could be rewritten only a few thousand times, current devices can be rewritten millions of times, ensuring a long life.

CompactFlash (CF) was originated by SanDisk, a flash memory manufacturer, as an easily implemented, license-free, flash memory format. It can operate at either 3.3 or 5.0 volts without risk and, with the basic IDE/ATA circuits needed to function as a hard drive, is easy to implement with existing off-the-shelf components. In fact, a simple pin-out adapter converts the 50-pin CompactFlash to the 68-pin PC card format (PCMCIA) used in almost every laptop. The extra control circuits did increase the cost at the lower capacities relative to other formats, but they also fostered rapid and widespread adoption, lowering prices at higher volumes.

The original Type 1 CompactFlash was limited to 192 MB. The Type 2 is 50 percent thicker (5 mm) and has 20 percent more power, allowing 300 MB of flash memory. Any Type 2-capable device is also Type 1-compatible to prevent conflicts.

Ironically, the future of CompactFlash is not as flash memory technology but as storage. Newer manufacturing technologies, driven by various PDAs and other handheld devices, have forced peripherals to be smaller and smaller. The power available to both Type 1 and Type 2 CF cards has been increased to 500ma. This, as well as CompactFlash’s well-known IDE/ATA interface, has made the format suitable for new storage technology, such as IBM’s Microdrive.

IBM supplied one of the first Extended Type 2 devices by implementing their laptop hard drive manufacturing techniques to produce CompactFlash hard drives. The fairly widespread 340-MB Microdrive quickly replaced the short-lived 170-MB model, and 1-GB models are already being advertised for sale. Other non-flash devices include modems, Ethernet adapters, interfaces to mobile phones, Bluetooth wireless links, pagers, GPS, and even Smart Media readers.
Size: 36.4mm long x 42.8mm wide x 3.3mm (Type 1) or 5.0mm (Type 2) thickPower: Operates at both 3.3 and 5.0 voltsStandard Type 1: 75maStandard Type 2: 90maExtended Type 1 & 2: 500ma
MultiMedia Cards
The MultiMedia Card (MMC) is the result of Infineon and SanDisk cooperating to create the smallest-format-possible storage card. To compensate for the relatively low capacity of the MMC, the serial interface of the MMC allows up to 30 cards to be treated as a single memory cell. The small form factor allows smaller devices to take advantage of MMCs and still allows for greater amounts of memory in devices large enough to use multiple MMCs.

Plans exist to increase this format from its current 32-MB maximum to 128 MB in 2002 and possibly include additional features. An agreement between Infineon and Hitachi provides the ability to redefine the MMC standard to account for the inclusion of a Hitachi SuperH processor or other features. Various features, including encryption, secure data, or even onboard processing, will be possible on the MMC platform in the future. MMCs are 32mm long x 24mm wide x 1.4mm thick.

Smart Media
Initially introduced in 1995 by Toshiba as the Solid State Floppy Disk Card (SSFDC), Smart Media was the earliest widely accepted small-format flash card. Toshiba emphasized portability by making a 3.5-inch floppy disk adapter that allowed Smart Media cards to be used in almost any device.

Smart Media has not, however, been without problems. The early models ran at 5.0 volts and were available only in 2-MB formats. The capacity was quickly improved, but the licensing fees deterred many companies from manufacturing or using them. Toshiba was able to encourage consumer adoption of Smart Media by dubbing the cards “digital film” and including Smart Media cards with their relatively successful line of digital cameras. Confusion erupted when the newer 3.3-volt cards were introduced. Things got worse when it was determined that the new cards weren’t 100 percent compatible with older 5-volt devices and could even be destroyed if the device had strayed too far from the specifications.

Slight changes were made to the casings to prevent the cards from being accidentally used in noncompatible devices. Unfortunately, use of the different voltages continues and the competition has grown. Smart Media is no longer the only flash card on the market, and other formats are available that either have more than the Smart Media’s 64-MB maximum capacity or are significantly smaller, allowing for inclusion in ultra-slimline devices.

To combat the rapid growth of the other flash card formats, Toshiba has made the Smart Media specifications freely available. They hope to encourage new companies to take advantage of Smart Media’s digital film reputation and prevent current Smart Media manufacturers from switching to another format.
Size: 45mm long x 37mm wide x .076mm thickPower: 3.3 volts at 75ma
Sony Memory Stick
Unlike other open formats, for which multiple suppliers are available, Sony requires licenses for groups wishing to manufacture or utilize the Memory Stick format and is currently the only manufacturer of these devices. After the lessons learned in the past few years, it would seem unlikely that anyone would pin their star to a single proprietary format, but the wide range of Sony devices that are Stick-compatible ensure the Stick’s longevity in the consumer electronics market, if nothing else.

Only Sony-manufactured devices are currently Stick-enabled, but Sony’s Web site lists 69 manufacturers in a variety of fields that have signed licenses. There’s already a plethora of Stick-able toys, ranging from Sony’s just-released Palm-OS CLIE PDA to digital cameras, camcorders, VAIO personal computers, Walkmans, printers, and even AIBO robot dogs.

Currently, only 64-MB Sticks can be found, but 128-MB units should be out in early 2001 and 256-MB Sticks toward the end of 2001. The exact date isn’t clear, as the focus on pure flash memory units has been diluted, thanks to the new emphasis on non-Memory Stick devices. With the addition of the CLIE Palm-OS device to Sony’s lineup to complement the VAIO laptops, a number of Stick-format devices are being developed. Expect to hear about GPS, Bluetooth wireless units, digital cameras, and voice recorders in the near future, and possibly a name change to Application Stick or just Sony Stick. Sony Memory Sticks are 50mm long x 21mm wide x 2.8mm thick.

But what about…
I’m sure that some of you are wondering why I neglected to mention PC cards or the multipurpose Springboard modules for the Handspring Visor, while including the Sony Memory Stick. The majority of portable electronic devices are becoming very small, excluding PC cards from most of them. In the case of MP3 players and voice recorders, a PC card is as large as the entire device! Most of these memory formats are also PC card-compatible, making them suitable for use in operations with PC card devices. As for the Springboard, while it’s versatile, the module is still intended for only a single class of product: the PDA. Sony has such a diverse product line that both consumers and corporations could standardize on Sony and Memory Sticks, something not possible with any of the other proprietary device formats.

Will I be stranded?
All of these formats have sufficient industry support to be purchased with confidence. This is typically the only expansion slot available on the majority of these devices, so by the time any of these formats would be abandoned by the market, you’ll have already acquired virtually all the add-ons you need.

Price comparison
Now it’s time to determine which formats support the options you need at a price you’re willing to pay. Any given type of portable electronic device likely has at least one manufacturer utilizing the format you choose, but some types of manufacturers or specific companies are biased. Sony devices will use only Memory Stick components, just as Toshiba devices will be equipped with Smart Media wherever possible. Manufacturers of laptop or Windows CE products will be more inclined to use CompactFlash because the PC card controllers they already use in bulk can operate CF cards.

The following tables show the different memory capacities and current pricing of the media I discussed in this Daily Drill Down. Prices are according to on Sept. 12, 2000. You can peruse the list, comparing the various memory and non-memory devices in those formats that are either already available or scheduled for release. Prices are subject to change and are in U.S. dollars.

Table A
Memory Capacity CompactFlash Type 1 CompactFlash Type 2 MultiMedia Card Smart Media Sony Stick
8 MB $24   $30 $15 $29
16 MB $27   $44 $30 $32
32 MB $54   $85 $54 $49
64 MB $108     $120 $91
96 MB $174        
128 MB $229        
192 MB $435        
256 MB   $531      
300 MB   $569      
340 MB (IBM Microdrive)   $210      
Storage expansion cards price comparison

Table B
  CompactFlash Type 1 CompactFlash Type 2 MultiMedia Card Smart Media Sony Stick
PC card adapter $9 $9 ? $34 ?
USB adapter $23 $23 $37 $39 $51
Parallel port adapter $45 $35 $44 ? $65
3.5-inch floppy adapter N N $63 $53 $61
Ethernet card ? Y N N ?
Modem Y Y N N P
Bluetooth ? P N N P
Encryption P P P P P
Voice recorder ? ? N N P
Digital camera ? ? N N P
Pager Y Y N N ?
Smart Media reader N Y N N N
Non-memory devices available or advertised for future use
N – Not on the market
Y – Already on the market
P – Planned for future release
? – These devices are possible within the format but have not been specifically mentioned on a product list or press release.

James McPherson has served his time in the trenches of technical support, honed his skills as a network administrator, and still managed to complete a B.S. in Engineering. After working for four different companies without changing offices, he is currently a freelance consultant and the bane of computer salesmen everywhere.

The authors and editors have taken care in preparation of the content contained herein, but make no expressed or implied warranty of any kind and assume no responsibility for errors or omissions. No liability is assumed for any damages. Always have a verified backup before making any changes.