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By Chris De Herrera 
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PDA/HPC Data Storage and Peripherals
By Chris De Herrera, Copyright 1996-2000
Version 1.11  Revised: 5/7/2000

All trademarks, copyrights are owned by their respective owners.


There are a few different types of data storage and peripheral cards now available for PDA/Windows CE users:

  • PC Cards - Data Storage and Peripherals

  • CompactFlash - Data Storage and Peripherals.

  • Miniature Cards - Dram and Data Storage.

  • Multimedia Cards/Secure Digital Cards - Data Storage


     Picture:  From the right and clockwise, PC Card, Compact Flash, and Miniature Card.

This paper will assist the reader in understanding what these cards can do and how they are used.


The PCMCIA (Personal Computer Memory Computer International Association) card or simply PC Card is a standard for peripherals for PDA (Personal Digital Assistant), H/PC (Handheld Personal Computer), notebook computers and desktop computers. Each peripheral is the same size as a credit card but thicker. There are 3 standards for thickness:

  • Type I cards are 3.3 millimeters thick. Most of these cards are SRAM cards. All Type I cards can be used in any Type I, II or III slot.

  • Type II cards are 5 millimeters thick. This is the most popular size of PC Card. They can be ram cards, modems, and other communications devices.

  • All Type II cards can be used in any Type II or III slot but not in a Type I slot.

  • Type III cards are 10.5 millimeters thick. Most of these cards are hard disks. All Type III cards can only be used in Type III slots not in Type I or II slots.

Each card requires driver software on the PDA/H/PC/Notebook or desktop computer to use them. Most software is release 2.0 or greater. Release 2.0 defined card and socket services to allow for standard drivers to make cards work. The card services are provided by the manufacturer of your computer, but the socket services may be provided with the PC card. Although PC Cards can be used in a wide variety of systems, not all PC Cards are compatible with all devices.

There are the following varieties of memory cards:

SRAM Cards - A static ram card that comes in 512k, 1mb, 2mb sizes. These are all Type I cards and are supported by all devices. Each card has a battery that powers the card when it is out of the computer. The battery must be changed about once a year. These cards are the fastest PC card storage devices available (over 1mb/sec). Each device can store data in a different format, so interchangeability of data stored is not guaranteed. The Apple Newton, Amstrad PDA 600 and the Sharp Zaurus do not support the standard PC format for cards. The Casio Zoomer, HP100/200LX, HP OmniGo 100, H/PCs do support the standard PC format.

ATA Flash Cards - An ATA Flash card is accessed like a hard disk. The ATA Flash cards are available in sizes from 1.8mb to 85mb. ATA Flash cards do not have a battery. All information is stored permanently (no power required) at the time it is written. These cards are relatively fast for reading (about 256k/sec) but very slow for writing (about 50k/sec). The writing is done slowly to reduce the amount of power required to operate the card. Sandisk (formerly Sundisk) is the leading manufacturer of ATA Flashcards, as is IBM. Each ATA flash card is formatted to be compatible with the standard PC format. The Apple Newton can not use these cards. The Casio Zoomer, HP 100/200LX, H/PCs and the Sharp Zaurus (with special drivers) can use the cards. The HP OmniGo supports these cards but is unstable due to their additional power requirements. HP does NOT recommend using them in the OmniGo 100.

When using ATA Flash cards it is recommended that you NOT use Alkaline batteries to power your PDA. Some Alkaline batteries have a high internal resistance that prevents the battery from supplying the peak currents the card requires for writing. This problem occurs randomly, so you may go for months safely and then suddenly lose all your data. Eveready Lithium Energizers are okay, as are Nickel Cadmium and Nickel Metal Hydride rechargeable batteries if your PDA can use them.  My Battery FAQ has more details on how PDAs/HPCs use power.

Linear Flash Cards - A Linear Flash card is accessed as a list of addresses for data. Linear Flash Cards are available in 2mb, 4mb, and 8mb sizes. The Linear Flash cards do not have a battery. All information is stored permanently at the time it is written. Intel is the leading manufacturer of Linear Flash cards. Each Linear Flash card is formatted differently, although there is a standard for PC cards called Microsoft Flash File format. These cards are compatible with the Apple Newton and Sharp Zaurus, but each has a different format. These cards are not compatible with the Casio Zoomer, HP100/200LX or the HP OmniGo 100.

Other RAM Cards - There are other types of ram cards that were created originally, but are no longer used, such as IDE format cards and Dram cards. These cards are not compatible with any of the current PDAs. They were created prior to the PCMCIA standards to fill a specific need.

Modem Cards - Most modem cards are Type II devices. The modems require much more power to operate (100mA or more!) than SRAM or Flash cards. This means that your batteries will be used up very fast. I recommend that you remove your modem card if you are not using it. Some PC Card slots do not power down when they are not in use! Each modem is composed of a standard UART called a 8250, 16450 or 16550 UART. Each modem uses the Hayes AT command set to send and receive commands including faxes. Due to the differences in the commands that each modem supports, you may need an additional driver in order to use your modem with your PDA/Notebook or Desktop computer. Also, note that 28.8kbps, 33.6kbps, and 56kbps modem cards generally draw too much power to use in a PDA; stick with 14.4kbps or lower.  My PC Card Modem Power FAQ has the details on the power consumption of various PC Card modems.

Combination cards - There are currently two cards available that combine Flash memory with a modem. The Smart Modular card is 2400 bps data/14400 bps FAX, and has 2, 4, or 6 MB of FlashRAM. The EXP ThinFax is a 14400 bps data/14400 bps FAX card, and is available with 2, 4, or 8 MB memory. These cards work in the HP100/200LX, and may work in other PDAs. Check with the manufacturer to be sure, however.  Also, Socket Communications has announced a PC Card with Ethernet and a serial port.

Other types of cards -  There are several other card types available for specialized needs, including LAN (Ethernet and Token Ring), radio modem, pager, and bus expansion. These are beyond the scope of this tip, but if you need information on these devices, please e-mail me and I will try to assist you.

So all PC Cards are rated as to their size and their software compatibility such as:

  • Verbatim SRAM Card - Type I, PCMCIA Release 1.0 compliant

  • Sandisk ATA Flash Card - Type II, PCMCIA Release 2.0 compliant

  • Intel Flash Card - Type II, PCMCIA Release 2.0 compliant


CompactFlash cards are used for data storage in PDAs, H/PCs , Palm PCs and Digital Cameras. Essentially, they are ATA flash cards in a smaller package (approximately 1 3/8" x 1 5/8" x 1/8"). As a matter of fact, with an adapter (provided with the purchase of Sandisk CompactFlash Cards) you can use these cards in a Type II PC Card Slot. These cards use the standard PC format even in digital cameras so that you can transfer and use the data easily on other systems. Currently these cards are supported by Handheld PCs and Palm-size PCs. The CompactFlash Association has adopted CompactFlash type II for larger devices and the CompactFlash CF+ for peripherals. Special drivers for peripherals will be required.  An example of using CompactFlash slots for peripherals is the new Palm-size PC.  It uses a 5mm thick card to support paging, modems, Ethernet, etc.  Existing CompactFlash slots will not accept the new CompactFlash type II cards or CompactFlash CF+ peripherals.  The CompactFlash CF+ cards that Socket and Pretec have announced are all of Type I thickness.  They will work with existing CompactFlash PC Card adapters so that you can use these devices in both your Handheld PC and Palm-size PC.

Sample Pretec CompactFlash CF+ Devices



Miniature cards are a new standard that is designed for memory and data storage. These cards are even smaller than the Compact Flash but there is no planned support for peripherals. They were designed to reduce the cost of data storage and increase the ruggedness of the cards. They have no pins or holes for pins to go in, unlike PC Cards or Compact Flash. Currently there are very few devices that use Miniature cards but one of them is the Philips Velo. It uses Miniature cards for ram expansion and flash data storage.

Iomega Clik!

In the near future you will be able to hook up the Iomega Clik! drive to your Windows CE Handheld PC.  This will be done with a PC Card adapter and a cable.  The Clik! disks hold 40 MB of data which can be accessed just like any other storage device to Windows CE.  The Clik! disks are the size of a quarter - including the thickness. Iomega is now shipping the Clik! drive!



Ioptics OROM

This revolutionary product will allow users to store up to 128mb of storage in a very small package called a data card.  OROM (Optical Read Only Memory) is very fast - similar to a hard disk but there are no moving parts! This technology is similar in function to the CDRom for desktops and laptops.   It will allow you to carry around a lot of information and access it quickly.

Microsoft has invested in Ioptics and there has been discussion in the press about using the OROM with Windows CE.  According to Ioptics, they are expecting prototypes by the end of this year.  Production units are expected 4Q99.

IBM Microdrive

IBM microdrive

Courtesy of International Business Machines Corporation. Unauthorized use not permitted

The IBM MicroDrive is 170, 340, or 1,000 MB CompactFlash CF+ type II hard disk. It is the smallest hard disk, weighing less than an AA battery (20 grams) and will be able to be used in digital cameras as well as handheld or "companion" PCs.  It spins at 4500 rpm, seeks at 15ms, and uses Enhanced Adaptive Battery Life Extender 2.0 power management to extend battery life.  It uses 3.3 volts at 500 mA to operate which is more than most current handheld devices can provide. Currently Canon, IBM, Hewlett-Packard Company, Hitachi, Ltd., and Minolta Co., Ltd, are evaluating using the MicroDrive in future devices.  

Halo Data Microdrive

HandCassiopeia.jpg (23345 bytes)

Halo Data offers the first and smallest hard drive in their MicroDrive. It is a Type I CompactFlash hard disk with 250 MB of data storage.  With power consumption of 250 mA in write and 50 mA for standby it uses less power than the IBM MicroDrive listed above.  The current price is anticipated to he $299.  It also appears rugged with the ability to withstand a 200 G shock while operating and 1000 G shock while not operating. Look for the Halo Data MicroDrive in the near future.

Addonics LS-120 and Zip Drive

Addonics has announced a driver to allow Windows CE users to use their LS-120 Superdrive, PocketZip and MobileZip drives with their H/PC and H/PC Pros.  The driver costs $39.  This adds additional capabilities for data storage in Windows CE.

Adaptec Slim SCSI 1460

Adaptec is now offering a driver for their Slim SCSI 1460 for sale on their website.  It offers support for hard disks and removable storage like the Iomega Zip drive.  In the future they plan on offering CDRom support as well.


As you can have read, the most popular type of data storage and peripherals for PDAs/HPCs are PC Cards. These tiny cards provide us with the capabilities and low power requirements needed by mobile users. The newer Compact Flash and Miniature Cards provide us with smaller options for additional data storage with lower power usage. That's about all the information about data storage and peripherals

Let me know if you have anything new to add to this by E-mailing Chris@Pocket PC FAQ.

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