e01c082.PDF

GENERAL INTEREST

Memory Modules

CompactFlash, MemoryStick, SmartMedia, MMC,

SDC and others

By Guy Raedersdorf

These days, solid-state-memories are available in all shapes and sizes. It is

becoming more and more difficult to keep up-to-date with all the different

properties, advantages and disadvantages of the many types of memory

modules. Reason enough, therefore, to devote an article to these.

advertisements for photographic

equipment to obtain an overview of

the state of affairs: one makes use of

CompactFlash, another uses Smart-

Media and the third uses Memory-

Stick.

There are several manufacturers

of memory modules around the

world. SanDisk, the inventor of Com-

pactFlash, is one of the more impor-

tant and most active of manufactur-

ers. This company possesses 31.3%

of the market share, Toshiba 20.5,

Sony 13.8, Hitachi 8.7, Samsung 7.9

and the others 17.8%.

The various types

We will now examine the different

types of memory modules up close.

In the last few years, the appearance of new

electronic products on the market has been

ever increasing. The movie camera has

already lost the battle with the electronic ver-

sion, still cameras are being replaced with

digital models and even the humble diary is

being threatened by the pen-computer. All

these products have to store their information

(photos, appointments) somewhere, prefer-

ably on a media without moving parts or bat-

teries. For this purpose, manufacturers have

designed memory modules with a large

quantity of non-volatile memory elements.

Just as has happened with many other prod-

ucts in the past, manufacturers have not been

able to limit themselves to a single world-

wide standard. Therefore, we now

encounter various types that are

(solely on different dimensions

alone) not mutually interchangeable.

The most common memory mod-

ules are the CompactFlash (38%),

SmartMedia (35%) and MemoryStick

(approximately 24% market share).

The rest (SD, MMC and others)

account for the remaining 3%. Not

less than 7 different families of mem-

ory modules ﬁght for their position in

the marketplace, and make desper-

ate attempts to gain the favour of the

potential customer.

You only need to look at a few

CompactFlash

The CompactFlash (CF) with its

dimensions of 42.8 x 36.4 x 3.3 mm is

quite large, nearly twice as large as

the MemoryStick. It was developed

at the SanDisk laboratories and

exists in various capacities from 4 to

512 MB ( Figure 1 ). The CF has a con-

troller on board, so that it may be

used in non-intelligent adapters.

Note that two types of CF-module

exist, type 1 and type 2, which only

Elektor Electronics

12/2001

GENERAL INTEREST

differ in thickness. The first is

3.2 mm thick and the second is 5 mm

thick. The CF, together with the

SMC, are the only ones with a paral-

lel interface.

(Memory Stick Duo), especially

developed for equipment that

requires ultra compact modules. This

version measures 31

1.6 mm

and weights 2 g! With the aid of an

adapter the MSD re-acquires the

dimensions of the original MS.

SmartMedia Card

The SmartMedia Card (SMC) is

about the same size as the CF and is

mostly known from the ﬁrst portable

MP3-players. It was developed in

1995 at the Toshiba laboratories and

exists in capacities from 4 to 128 MB

( Figure 2 ). The very thin SMC occu-

pies about 1/3 the dimensions of a

credit card. This module does not

have any intelligence of its own and

therefore has to be placed in a suit-

able reader.

MultiMedia Card

The MultiMedia Card, abbreviated

MMC, was introduced in 1997 by

SanDisk and Siemens ( Figure 4 ).

This device is a flash memory with

serial interface; reading occurs at a

respectable 13.7 to 20 Mb/s, writing

varies from 3.2 to 20 Mb/s. Note that

two different types of MMC exists:

the MMC 1 and the MMC 2, which is

slightly thicker.

The MMC has 7 contacts and is

available in capacities from 4 to

64 MB.

Figure 1. The Compact Flash is one of the most

universal memory modules.

MemoryStick

The MemoryStick from Sony, (MS to

the connoisseur, see Figure 3 )

appeared relatively late on the mar-

ket, compared to the other well-

known memory modules (such as

CompactFlash and the SmartMedia

Card). Sony makes use of the MS in

many new devices, such as the

astonishingly small player of audio

files in the ATRAC3-format, a com-

petitor to MP3. Initially it appeared

that the MemoryStick was going to

be a proprietary solution for the

Sony-world, but in recent times other

manufacturers have also developed

an interest.

The MS is currently available in

capacities of up to 128 MB, but mod-

els with 512 MB or even 1 GB are

planned for release towards the end

of 2003.

The internal construction of the

MS consists of a ﬂash-memory and a

controller. The transfer of data is

achieved over a three-wire (Data,

Clock and Bus) serial interface in

blocks of 512 bytes at a maximum

frequency of 20 MHz.

A small notch at the bottom of the

MS is used to protect the data from

being inadvertently overwritten, a

feature that it shares with the SD-

module.

There is also an MS, the Magic-

Gate, which is white in colour. This

version is specifically intended for

the reproduction of digital data ﬁles

(audio and text) that are subject to

sesses a unique serial number.

Another variation is the MSD

mum 32 MB.

– The Miniature Card; the dimensions are a

quarter those of a standard PC card.

– The SRAM module, ﬁtted with a lithium bat-

tery to preserve the data; currently the

maximum capacity is 6 MB and the device

is very expensive.

– The ATA FlashDisk from SanDisk.

– The MicroFlashDisk

– The MicroDrive from IBM. A miniature hard

disk in CF2-format with a capacity of up to

1GB

– The Click Drive from Iomega, a mini-ﬂoppy

with a capacity of 40 MB.

SD (Security Digital) Card

This card appeared in 2000 and

traces its origins back to SanDisk,

Toshiba, and Matsushita. Except for

the thickness, which is 2.1 mm, its

dimensions are the same is for the

MMC. The SDC exists in capacities

from 8 to 64 MB and has 9 contacts.

PC Card

The PC Card ( Figure 5 ), its shape is

analogous to the normal PCMCIA-

module and its thickness corre-

sponds to either a type 2 or type 3,

has a capacity from 8 MB to 1 GB.

Work is already in progress on a

2 GB version; this is not all that

amazing considering the difference

in dimensions between the CD and

the PCMCIA module (which in addi-

tion to the memory also has to find

room for a controller).

The technical aspects

Table 1 lists the most important differences

between the various types of memory mod-

ules.

But this doesn’t say anything about the

technical aspects of these cards, something

And the others?

There are a number of other, lesser

known, memory modules, such as:

– The ATA Flash Card, a kind of PC

card with higher specifications.

The ATA Flash Card makes use of

a ﬂash-memory and NAND-gates.

The maximum reading speed is

1.5 MB/s and the write speed is

3MB/s. These modules are avail-

able in sizes ranging from 8 MB to

2 GB (type 3).

– The Linear Flash Memory Card,

which is used, among other things,

in the Alesis synthesiser; maxi-

Figure 2. The SmartMedia Card is commonly

used in MP3 players and digital cameras.

12/2001

Elektor Electronics

GENERAL INTEREST

to keep up with the current version

of the program. It is also possible to

optimise the controller for different

applications or circumstances.

Reading the modules

Because there are so many different

types of memory modules, a simi-

larly large number of readers have

been developed in order to be able to

connect them all to a computer.

The PC Card, as we mentioned

earlier, is not a problem, since it ﬁts in

a PCMCIA slot. All other types need

some sort of provision to read them

back.

One very simple solution is the:

Figure 3. The standard model Memory Stick is always blue in colour.

that will be of particular interest to readers of

Elektor Electronics .

We have taken a memory card from Lexar

Media as an example. Lexar is one of the few

manufacturers of memory modules who

develop and manufacture their own con-

trollers. This way, they can incorporate inter-

esting features.

The writing speed of a memory module is

an important speciﬁcation. This is of particu-

lar concern to the professional photographic

industry. This speed is labelled on a Lexar

memory module: 4×

PC Card adapter

This is a type of adapter ( Figure 7 )

that allows a memory module to be

plugged into a PCMCIA-slot, that is

already built into the vast majority of

laptops.

This type of adapter is available

from various manufacturers and for

several different types of modules,

such as the MemoryStick, the CF-

card and the SmartMedia Card. They

are very easy to use. After the

adapter, ﬁtted with a memory mod-

ule, is plugged into a PCMCIA-slot,

the computer will automatically

recognise the PCMCIA-card. The

first time, Windows will install the

necessary driver. Thereafter the

memory is available is if it were an

additional hard disk.

Because there aren’t very many

desktop computers with a PCMCIA

slot, another solution has been

developed:

for normal use, 8×

for

amateur photographers and 12

for the pro-

fessional. Every ‘× ’ stands for 150 kB/s so that

data storage occurs at a rate of 600 kB/s to

1.8 MB/s. Because modern digital cameras

generate very large ﬁles, these differences are

clearly noticeable.

A unique aspect of the CF-modules from

Lexar is the integrated USB (refer to the dia-

gram in Figure 6 ) in the module itself, hence

the name CF+. This way it is possible for the

user to use a cheap cable, named Jumpshot

(in the photo at the start of this article in the

middle at the top), to connect the module

Figure 4. The MultiMedia Card has the

dimensions of a postage stamp.

directly to a USB-port on a PC or

MAC. The USB-port on board of the

CompactFlash+ is then automati-

cally activated and appears to the

PC as a normal drive.

Another feature of the Lexar prod-

ucts is the presence of a Space Man-

ager function in the controller, to

optimally utilise the ﬂash-memory. In

contrast with magnetic mass-stor-

age devices where a write command

overwrites the previous data, a ﬂash-

memory has to be erased ﬁrst before

new data can be written. The Space

Manager technology is based on the

indirect exchange between physical

and logical addresses, in such a way

that it is possible to ﬁll sectors with

data without having to erase them

first. At a later time, when the sys-

tem is idle, unused data blocks are

erased.

The last remarkable technical fea-

ture of the CF+ is the ‘programma-

ble firmware’. The controller pro-

gram resides in the ﬂash-memory. At

run time, the software is copied to

the internal RAM. This way it is easy

Diskette-adapter

The diskette-adapted is, as the name

implies, an adapter shaped like a

3.5”-diskette ( Figure 8 ). This adapter

is usually supplied with an appropri-

ate driver. They are also easy to use.

The adapter (with the memory mod-

ule fitted inside) is placed into the

floppy-drive. The data transfer is

faster than with a diskette.

Diskette adapters are available

for different types of modules, such

as for the MemoryStick, the Smart-

Media and the MultiMedia Card.

External readers

Just about every memory manufac-

turer also has an external reader,

Figure 5. The PC Card module has currently

the largest memory capacity.

Elektor Electronics

12/2001

GENERAL INTEREST

Table 1. Physical properties of the current memory modules.

(source : Sony)

CompactFlash

Memory Stick

Memory Stick Duo

MultiMediaCard

SD Card

SmartMedia

Dimensions (mm)

42,8 x 36,4 x 3.3

50 x 21,5 x 2.8

31 x 20 x 1.6

32 x 24 x 1.4

32 x 24 x 2.1

45 x 37 x 0.76

Mass (g)

8 to 15

1.5

Volume (cm3)

5.141

3.010

0.992

1.075

1.612

1.265

Origin

SanDisk (1994)

Sony (1998)

Sony (2000)

SanDisk (1997)

SanDisk (2000)

Toshiba (1995)

Number of contacts

16, 32, 64, 96, 128,

192, 256, 384, 512

Current capacity (MB)

8, 16, 32, 64, 128

8, 16, 24, 32,64, 128

4 ... 64

8, 16, 32, 64, 128

Maximum data speed (MB/s)

1.8 (E) – 2.45 (L)

0.375 E) 1.75 (L)

ID-number

SDMI-norm

ID-number

SDMI-norm

ID-number

A number of

interesting websites:

Bank

RAM

ROM

USB

Interface

ATA

Interface

U.P. Control

U.P. Addr/Data

www.memorystick.org

A lot of information can be found here

regarding the MemoryStick. This site is

intended for developers, but is deﬁnitely also

of interest to readers who would like to

know more about this memory module from

Sony.

Data

Buffer

Manager

Address

Decoder

Microprocessor

Flash

Add/Data

Flash

Control

Space

Manager

ECC

www.sandisk.com

All information about SanDisk products can

be found here.

010075 - 11

Flash Memory Address, Data and Control

Figure 6. Schematic overview of a CF+-module from Lexar Media (source: Lexar).

www.lexarmedia.com

Lexar Media, just like SanDisk, has a consid-

erable offering of various types of memory

modules (even the MemoryStick).

mainly USB models, to connect a

memory module to a computer. San-

Disk has the Imagemate, in versions

for CompactFlash, MultiMedia and

SmartMedia. The SecureMate is

speciﬁcally intended for Secure Dig-

ital modules.

Currently there also exist readers

that can read both CD as well as

SMC-modules and have two differ-

ent connectors.

www.sdmi.org

Here you can ﬁnd out about the protection

of copyright sensitive material (SDMI =

Secure Digital Music Initiative).

(010075-1)

Figure 7. A PCMCIA-adapter from Lexar for CF and CF+-modules.

Figure 8. This diskette-adapter has been

designed for MMC modules.

12/2001

Elektor Electronics

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