In a previous journal post , we highlighted that AMD look like they are being taken-up by UMPC manufacturers. The Pepperpad Plus was the first device that we had heard of that might use an AMD processor. We’ve also heard the news that Samsung may start using AMD processors. Now is probably a good time to take a closer look at the AMD processor range that relates to UMPC’s

Back in 2002, AMD bought the Geode range of processors from National Semiconductors. With it, they put themselves on a path to producing low-power embedded chips for mainly industrial markets. Since then, AMD have developed a range of processors that cover the very low-end up to traditional PC markets.

The range starts with dedicated media chips (the Alchemy range), goes through the Geode GX range (aimed at thin client technology), the LX range and ends up with Geode NX processors derived from existing Althlon technology.

The two ranges that could be interesting for a UMPC developer are the Geode LX and Geode range

Geode LX – x86 with a unique bus.

The Geode LX CPU’s are know as ‘Computer-on-module’ designs. They use an x86 instruction set but use a different type of bus architecture to ‘normal’ PC’s. The traditional northbridge functionality is self-contained within the CPU (the graphics and memory controller) which means that you are locked into this as the only graphics option. It could be possible to run a 3D graphics co-processor on the PCI-bus perhaps but the power disadvantages would be too big for a UMPC design. (Remember that with current battery technology, avaerage total power dissipation of the board needs to be kept at around the 10W mark.)

The traditional southbridge function (input/output) is available in a ‘companion’ chip. which also restricts choice. The companion chip, the CS5535 , can handle PCI, USB 2.0, IDE (to ATA-6), serial, parallel, audio, ACPI, real time clock and the all-important ‘pc-beep’ support!

The LX range consists of the LX700 and LX800 and it is the LX800 which has been highlighted by Pepperpad as a possible CPU solution for their design. Its clocked at 500Mhz, has a low-power profile, supports Windows XP variants and is a relatively cheap component.

Our thoughts at the moment are that it’s a borderline processor. Its got the right power profile but Its not going to be powerful enough to enable the full Windows experience on a UMPC. With rich browsing (flash, pcockwave, java and other client-side processing) it could struggle to provide a good user experience in such a heavyweight operating system. High-bitrate videos could also be a problem although the graphics capabilities are not fully tested at this stage. Its possible it could perform well with an embedded version of XP or an efficient Linux design as a ‘web pad’ or some other home device where customer expectations wouldn’t be too high but if used to build an Origami-class UMPC, it will certainly underperform the existing devices with VIA and Intel solutions.

The next step up – Geode NX.

The NX range uses a very typical architecture and in-fact is derived from AMD’s existing Athlon technology and uses a Socket-A fitting rather than being an embedded (soldered direct on to the motherboard) processor. The bus architecture allows alternative north and southbridge chips to be added allowing flexibility in overall design and capability.

The range includes the Geode NX 1250@6W processor, the Geode NX 1500@6W processor and the AMD NX 1750@14W. The watt rating indicates average power consumption. By comparison, VIA says that the VIA C7-M ULV has a 1Watt average consumtion so the 1750 part is obviously not for the UMPC market leaving the 1250 and 1500 (667 and 1Ghz clockrate respectively) as the interesting parts. They are more powerful CPU’s than the VIA C7-M ULV. According to the Epiacenter report on the fanless DB1500 development board (using the NX 1500 and SiS chipset) the performance is suprisingly good.

Looking at the benchmarks earlier it becomes obvious that AMD’s Geode NX is a very potent processor and it easily beats out VIA’s C7 CPU. The memory performance is also excellent so there’s little else to be desired for in terms of raw performance – Epiacenter.

Epiacenter’s comments are about the NX1500 in a board setting with SiS chipset but knowing how many low-power boards Epiacenter have tested, one should’nt take these comments lightly.

Summary

AMD have a rich line-up of low-power processors but there’s only two or three that are really fitting for the UMPC market.

The LX800 could potentially form the core of a web-pad or home internet device and when combined with Linux, provide a really cost effective solution. With its x86 architecture, the range of Linux applications is un-ending and this could be make a really interesting (and hackable!) alternative to the existing Linux/RISC-based devices (the Nokia 770 and current Pepperpad.) whose Linux support is very limited in comparison.

The NX 1250 and 1500 chips lie at the top-end of the UMPC spectrum. The power profile is quite ‘heavy’ and would require high-quality components (LCD, Wifi, Battery) to keep the total power drain of a UMPC board down to useable levels.

Regarding the Samsung-AMD/Via rumors, we think that Samsung has three options:

1. Use the Geode NX1250 and pair it with high quality components from the Samsung inventory to make a UMPC.
2. Go into the low-end of the market and use the LX800 to make a consumer-level (thats where Sasmung are marketing right now) ‘Carrypad’ (we had to get that in!) that uses Embedded XP or Linux operating system.
3. Use the VIA-C7-M to make a cheaper mid-range device.

Option number 1 requires high quality parts from the Samsung part bin and we guess that the production cost would be quite high. The third option would result in a device very close to the existing Samsung Q1 specifiation and would confuse customers. Our money lies with option 2. Samsung might bring in a very low end consumer level device for your sofa or car.

• More Intel ULV news. Core 2 Duos
• Pepperpad Plus – Bringing AMD into the UMPC market.
• A Carrypad software specification