Nuts and Bolts of Notebooks
Редакция THG,  26 января 2001



Before we jump onto notebook testing, I have to explain several things. Notebooks have different features that are partially unknown to the desktop market like PC Cards, daughter boards and batteries. The chipset and VGA requirements are also different from the needs of a desktop computer. To make matters worse, it is very easy to compare apples with oranges while comparing notebooks.

First I will explain the different notebook segments and later in this article the different notebook specialties.

Notebook Segments

I will skip PDAs in this guide and go directly for notebooks. The notebook market is divided into three major segments.

Segment #1: All-In-One


Everything you need is inside of the notebook. Floppy, HDD (hard disk drives) and CD/DVD-Drive are build-in. These models are also called three spindle solutions because Floppy, CD/DVD and HDD all use a spindle motor.

Most of those notebooks start with a 12" display and go up to a 14" display. The display is one of the most expensive components of a notebook. The preferred technology for such a display should be TFT (thin film transistor). TFT displays offer a much better quality and speed than the DSTN display. If you ever had the opportunity to compare a cheaper DSTN Display with a more expensive TFT Display, you will certainly stick to the TFT display. .

The weight of such a notebook is about 3kg with all drives included.

Segment #2: Thin and light

Thin and Light

When was the last time you used your floppy drive? When you possess a CD-ROM or network connection you will hardly need it at all. So why carry it with you?

Thin and light notebooks carry one to two drives inside and weigh less the 2kg. The missing drive(s) can be attached to the notebook with a proprietary connector or via USB. Display and battery would add to the weight of any notebook, so both are stripped down too. 8.9" to 13" displays and less battery cells than an all-in-one notebook are used. Some of those ultra light notebooks use displays with non-standard resolutions like 1024x480 to get the notebook smaller in size and weight.

Segment #3: Meganote


Meganotes are desktop replacement products for the small and prestigious high-end market. Every little gadget and gismo that is available for money can be found inside, including large 14" to 15" displays with very high SXGA+ 1400x1050 or UltraXGA 1600x1200 resolutions.

CPUs of 800+ MHz, memory sizes above 256MB, wireless LAN, DVD and huge 30GB hard drives in combination with the large displays don't come cheap. This is a notebook for the desk of a manager to show off or a real power user. Most road warriors don't like carrying such a heavy and expensive device around.

Notebook Specialties

Notebooks have different requirements than desktop PCs. Connectivity and mobility is the primary focus of a notebook. PCMCIA, PC Card, MiniPCI and Mobile Audio/Modem Daughter Card are helping the road warriors to get connected. Ni-Cad, Ni-MH and Li-Ion along with smart-battery technology provide the necessary power. The chipset used in the notebook motherboard must provide several power saving options and the 3D performance of the notebook VGA chips doesn't have as high of a priority as in desktop systems.

Memory And Connectivity With PCMCIA And PC Cards

PCMCIA/PC Cards were established as the standard for expansion of a notebook. Due to space limitations it is not possible to add an ISA or PCI slot to a notebook.

Type I
Type I = 3.3mm thick

Type II

Type II = 5.0mm thick

Type III

Type III = 10.5mm thick

1989 the Personal Computer Memory Card International Association was founded to establish standards of integrated circuits cards for mobile computers.

1990 the PCMCIA 1.0 was released to the public with the Type I and Type II PC Card form factor.

1991-1994 the releases 2.0 to 2.1 followed to add support for Type III cards.

1995 saw the establishment of the PC Card standard, with 3.3V and DMA support, 32-bit Cardbus bus mastering and Zoomed Video.

The first implementations of PCMCIA cards were modem cards or memory cards that added some main memory to the system. Nowadays you can get PCMCIA cards with 56k modem, ISDN, GSM and LAN support in just one small Type I or Type II PC Card.

Memory And Connectivity With PCMCIA And PC Cards, Continued

There's two different ways of connecting the standard RJ11/RJ45 plugs to such a small card. One approach is the so-called "dangle".

Dangle Cable

The dangle cable is connected to the PCMCIA card with a very flat proprietary plug. The other end of this cable (dangle) carries the usual LAN or Modem connectors. While the dangle-solution ensures a small size of the PCMCIA-card, it carries the risk that the small and fragile dangle-connectors on the PCMCIA-card get damaged if the cables are pulled forcefully - something that typically happens when somebody stumbles over the cables.

To tackle this problem some PC Card vendors have created the so-called 'Realport' cards.

These cards are all of the huge Type III size, occupying two card slots of Type II or Type I cards. You can directly plug your LAN/ Modem/ISDN cable in this card, but you are scarifying one Type II card slot of your notebook. Most notebooks only come with two Type II slots, making a RealPort card the one-and-only PCMCIA-card that can be used at the same time.

Memory And Connectivity With PCMCIA And PC Cards, Continued

It is important to consider the bandwidth of such devices, i.e. the path inside the notebook.

16-bit I/O Transfer 16-bit DMA Transfer Cardbus (32 bit burst mode)
Byte mode 3.92 Mbytes 10 Mbytes/sec 33 Mbytes/sec
Word mode 7.84 Mbytes 20 Mbytes/sec 66 Mbytes/sec
Dword mode 132 Mbytes/sec

The performance increase with the Cardbus 32bit marked the giant step from the old ISA world to the new PCI world. A modem card might not benefit from the 32bit access, but a 100Mb network card does.

Together with the 32bit transfer, the PC Card specification added the ZV (Zoomed Video) Port. The ZV Port is a point-to-point unidirectional video path from a PC Card to a graphics chip plus an audio chip.

Memory And Connectivity With PCMCIA And PC Cards, Continued

With such a ZV Port PC Card you can add a camera or MPEG2-decoding (DVD-decoder cards) to your Notebook.

Recently Intel pushed forward with two new Standards for Mobile Computing, which are 'MiniPCI' for internal PCI cards and 'MDC' (Mobile Audio/Modem Daughter Card). PCI slots are too big for a notebook, but there is a need for optional features like Ethernet LAN, token ring LAN or other upgrades like e.g. Bluetooth. A MiniPCI card provides the flexibility needed to react to the market for such features. Usually, a built-in notebook modem is a proprietary design for a specific notebook model. With all the certification needed to support a modem around the world, it is a nightmare to use that certified design for one notebook modem model only. In this case the MiniPCI and MDC standards help at lot.



The MiniPCI specification defines a small form factor daughter card for 32bit PCI bus that can be used in notebooks in which standard and small PCI cards cannot be used due to mechanical design constraints. A notebook with such a card can easily be upgraded and serviced. Much more important is the increased flexibility in the assembly of the notebook. The cost for such a card can be reduced by a 3rd party design and production of the MiniPCI card.

MiniPCI Built In

As you can see those cards are built into the notebook.

PCI Lan Card

Here you can see an example of a mini PCI Lan Card

It is important to note that MiniPCI Cards will not be available in the after sales market.

Mobile Audio/Modem Daughter Card

The mobile audio/modem daughter card (MDC) specification provides a mobile form factor and interface for audio and modem solutions based upon AC'97. The MDC will liberate modem board manufacturers from the burden of repeated certification of modem cards tailored for each notebook model. I believe that only the modem section of this specification is used inside the notebooks, which is why I only introduce the modem here.

Mobile Audio/Modem Daughter Card

Such a MDC Modem is quite easy to design and produce. The modem drivers are part of the audio driver.

MDC Card

An example of such a MDC card is taken from an ASUS L8400B Notebook.

MDC as well as MiniPCI do not support aftermarket upgrades to the sealed notebook, but I think it is still worth knowing about them.


The most important feature of a notebook is its mobility. Rechargeable batteries supply the power of the notebook. Like everything in the IT business there are several different options from cheap and heavy to expensive and light.

The most common rechargeable batteries being used in a Notebook are:

  • Nickel-Cadmium (NiCad)
  • Nickel-Metal Hydride (NiMH)
  • Lithium-Ion (Li-Ion)

Ni-Cad Ni-MH Li-Ion
Energy Density (W-Hr/kg) 40 60 90
Energy Density (W-Hr/l) 100 140 210
Operating Voltage 1,2 1,2 3,6
Lifetime (approx. Cycles) 1000 800 1000
Self Discharge 15%/month 20%/month 6%/month


In budget notebooks you will find Ni-Cad or Ni-MH batteries. The price difference to Li-Ion is about US$30. But wait before you start running to the next computer shack to get a Li-Ion battery pack. You should continue reading this portion of the article, because there are major differences between Ni-Cad, Ni-MH and Li-Ion batteries.

Ni-Cad and Ni-MH batteries are charged with a constant current. The charger monitors the battery voltage and temperature. It is looking for a rise of the battery voltage that usually occurs at the end of the charging cycle. Ni-Cad and NiMH have similar behavior except for the point close to the end of the charging process.


The temperature of NiMH batteries rises faster than 1°C/minute once the battery has reached the end of its charging cycle.


The charger of a Li-Ion battery uses a constant voltage for charging the battery.


The battery voltage will rise to the maximum battery voltage (in our diagram 4.2V) and then remain at a constant charging voltage, while the charging current slowly decreases. Once the current fell under the threshold value (80 mA in our example) the charger stops.

If you want to upgrade the battery of your notebook from a Ni-Cad/Ni-MH battery to a Li-Ion battery, you have to check with your notebook vendor if the charger inside your notebook can support that battery type.

Besides the weight and volume advantage of Li-Ion batteries, there's also the missing memory effect. This is a condition that occurs when a battery is charged to the same level several times. The battery develops a chemical memory of that level and will not allow a full charge beyond that point. Li-Ion batteries don't have this problem. The only disadvantage of this battery type is the fact that it doesn't like low temperatures.

Smart Batteries

The charging process mentioned above describes the so-called 'dumb batteries'. You have to save your data before the empty battery shuts off your notebook. Today's state-of-the-art notebook with its battery pack can give you a very precise status of the battery charge status. This is being achieved with the so-called 'smart batteries'. Notebook battery packs contain much more then just accumulators and a thermal sensor to detect the end of charging process.

Those batteries use a two-wire interface called System Management Bus (SMBus) that is based on the principle operations of I2C.

Smart Batteries

Using the I2C/SMBus the attached devices can provide vendor information, save its state, report errors, accept control parameter and return its status.

When AC power is supplied, the Smart Battery charger must charge the Smart Battery regardless if the notebook is running or not. The charge voltage and current as well as the temperature have to be controlled too. The Smart Battery charger gets a good portion of its information from the gas gauge board that is inside the battery pack. It contains a LMD (main counter and capacity reference / last measured discharge), a DCR (discharge count register) and a NAC (nominal available charge register). The discharge current is measured while compensating the temperature. All of this makes sure that the available battery charge can be used efficiently. That is to avoid that battery pack is under or overcharged. Before you get such a battery pack, it will run a learning cycle to be conditioned to its size and provide the maximum available power to the notebook.

This certainly explains why you should check for the notebook model before you go get a new battery pack.

Intel 440MX - 440BX's Little Brother

I2C/SMBus is supported by all current chipsets. Many notebook vendors currently use the i440BX chipset for their notebooks. The regular readers of Tom's Hardware Guide know this chipset from desktop motherboards. But there is also a virtually unknown chipset the so-called i440MX.

It is very important for a notebook designer to get everything as small as possible. A BX design needs real estate for two chips. The i440BX north bridge and the PIIX south bridge. The i440MX chipset includes the north and south bridge in just one chip.

Intel 440MX - 440BX's Little Brother

When you take a closer look at the picture above, you will notice that there is only 1 EIDE controller. There is no need for a second EIDE channel in a notebook with only 2 EIDE devices, the HDD and the CD/DVD drive. In the process of stripping down features, Intel engineers also removed the AGP port. A few features were actually added as well. The AC'97 link was introduced into the mobile chipsets first. With AC'97 it is possible to provide a cost effective audio solution and save space.

New chipsets like the mobile i815EM have the advantage of an integrated VGA controller that can use the main memory as its frame buffer. All these special chipset features might look strange from the desktop point of view, but from the notebook perspective it paints a different picture.

Notebook Graphics

The latest desktop 3D chips like those from NVIDIA come equipped with up to 64MB DDR-RAM. Some of these 3D solutions consume up to 40W of power. It is needless to say that this power budget is unsuitable for notebooks. In a mobile PC real estate and power consumption are more important then 3D performance. Most desktop users know the big 3D players ATI and NVIDIA. NVIDIA just introduced its mobile chipset Geforce2 Go. Besides this newcomer, ATI, Silicon Motion and S3 are the big players for notebook graphics solutions today.

  Silicon Motion S3
Features Lynx (SM910)* LynxE (SM81x)* Lynx3D (SM820)* LynxEM4 (SM710) LynxEM+ (SM712) Lynx3DM (SM721) Savage
Power / worst case 0.55W 0.55W 1.1W 1.9W
max. memory 4MB 4MB 6.5MB 4MB 4MB 16MB 16MB
built-in memory 4MB 2MB 2.5MB 4MB 4MB 8MB -
Dual View X X X X X X X
DVD support - - X - - X X
3D support X - X - - X X

* Phased out

  Nvidia Trident
Features Geforce2 Go ** Cyber 9525 DVD* CyberBlade XP Blade T16 Blade T64 Blade XP Blade XP Turbo
Power / worst case 2.8 W 2.3W 1.8W 2.0W 2.3W 2.6W
max. memory 32MB 2.5MB 32MB 16MB 32MB 32MB 32MB
built-in memory - 2.5MB - - - - -
Dual View X X X X X X X
DVD support X X X X X X X
3D support X X X X X X X

* Phased out
** Geforce2 Go is currently not a shipping product

Features Rage LT Pro Rage Mobility L Rage Mobility EC Rage Mobility P Rage Mobility M Rage Mobility M1 Rage Mobility 128 Rage Mobility M4 (AGP 4x) Rage Mobility M4 (AGP 4x)
Power / worst case 1.8W (w/4MB) 1.3W (w/8MB) 1.3W (w/8MB) 1.3W (w/8MB) 2.2W (w/8MB) 2.2W (w/8MB) 2.2W (w/8MB)
max. memory 8MB 4MB 4MB 8MB 8MB 8MB 16MB 16MB 32MB
built-in memory - 4MB - - 4MB 8MB 8MB 8MB 16MB
Dual View X - X X X X X X X
DVD support - X X X X X X X X
3D support X X X X X X X X X

Reduce Size - Mobile Graphics Chips With Integrated Graphics Memory

Memory consumes real estate. That is the reason why some mobile graphics chips come with built-in memory. A resolution of 1024x768x24bit requires 2.36MB for the display frame buffer. State of the art VGA chips provide 32bit color because it is easier to implement 32bit memory access. For 16.7Mio colors the graphics controller requires 224 bits. Some mobile graphics chips that only offer standard 2D-features are therefore equipped with a built-in 2.5 MB of graphics memory.

Fancy 3D functions that require Z-buffering cannot be used at high resolutions like 1024x768 with such a small VGA memory. If you want to take advantage of 3D functions for applications like Quake3, you must reduce the display resolution and the color depth or increase the size of the graphics memory.

Well-equipped notebooks use graphic solutions with 4MB or more memory. Many mobile VGA chips that offer reasonable 3D-features still require external memory. S3's Savage and Ati's Rage Mobility are also available with built-in memory. The frame buffer sizes vary from 4MB to 16MB. ATI and S3 use a technology called 'dual die' for built-in memory. The VGA die and the memory die are shipped in the same package. The notebook design is dramatically simplified and the graphics unit needs less valuable space.

Shared Memory - The Simpler But Slower Alternative

Soon we will see shared memory solutions for notebooks from Intel and SiS. A Part of the main memory is deducted and used for the VGA frame buffer. As you certainly know, low priced desktop systems are using these chipsets too. From the performance point of view this solution is not optimal. On the other hand there are a lot of advantages of these integrated VGA-solutions, which are predominately the power and size requirements and thus the price.

Dual View

Many mobile warriors use the notebook for presentations. It is often necessary that a beamer or a large CRT monitor is connected to the VGA-out. Dual View is supported within mobile VGA chips for quite a while. Typical desktop examples are Matrox 'Dual Head' or one of the new Geforce MX cards with 'Twin View'. Some of those mobile VGA chips also have a TV out option. The notebook designers do not always use this feature though.

A performance comparison of the graphic solutions will be an article of its own. Be aware that you have to stick with you VGA for the entire lifespan of the notebook.


Notebooks are real PCs and in some cases even a real desktop replacement. But there are several major differences. Everything inside a notebook is tailored directly to that model. When you want to upgrade or change the VGA card or the motherboard of your desktop computer, you can get replacement products from different vendors that will fit into your desktop computer. Notebooks have only very limited upgrade options. MiniPCI, MDC as well as PC Cards are standardized and provide some flexibility.

The battery makes the real difference from the desktop. Battery chemistry and capacity vary from model to model. Some notebooks support two battery packs, but this feature will add about 1 pound to the weight of the notebook. Mobile 3D graphics are one the rise, but about 1-2 years behind the performance of a desktop computer.

I (Uwe von der Weyden) have been a heavy user of notebooks for several years and models now. My desktop computer is running as a router and a place to store data. The advantages of the flexibility, the mobility and the TFT display let me forget the disadvantages like the slow HDD, the limited 3D performance and the high price of the notebook.

The notebook is much more of a technical challenge than a desktop computer. We at Tom's Hardware take the gauntlet and will explain everything about a notebook. We will start with a series of Tom's Hardware Style notebook tests very soon.


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