Transmeta obviously wanted to make the Efficeon processor as attractive as possible to potential partners in the portable computing industry, especially since the CPU is more or less directly competing with Intel's Centrino processor and chipset for success.

This would be the major reason for integrating the traditional northbridge functions into the chip itself. By increasing the complexity of the chip, Transmeta reduces the necessary complexity and expense of the chipset that compliments it. This should continue to make the Efficeon an attractive choice for low-power laptop manufacturers.

On the same note, the TM8620 (130nm process) and TM8820 (90nm) Efficeon processors are considerably smaller than the first Efficeon chips to hit market, at a planned 441mm square. The first generation Efficeon 8600 package takes up 841mm. By reducing the motherboard real estate that the chip takes up, further gains can be realized.

There is some suggestion that the 90nm (or smaller) versions of the Efficeon might find a home in the PDA market if partnered by a suitable motherboard design... but of course hard disk technology would have to catch up also. The idea of running a full Windows XP tablet edition on a Pocket PC sized device is tantalizing. OQO Technology have recently released a full WinXP PC with LCD display and 802.11b and Bluetooth, that measures no larger than a pack of playing cards. The device, called the OQO Model 1 is powered by the older 1GHz Crusoe TM5800-series Transmeta processor, but Efficeon-based versions may eventually appear.

In order to ensure the OQO is the first in a series of palm sized PCs powered by Transmeta processors like the Efficeon, Transmeta have partnered with Nvidia in the development of their Nforce 3 Go 120 chipset which is intended for ultra-portable devices. More on this in a moment.

Efficeon and Hypertransport

One of the more exciting features of the Efficeon processor is the inclusion of the Hypertransport bus, only before seen in AMD's Opteron and Athlon 64 processors.

Hypertransport (HT) is a high-speed data carrying method designed to replace or supplement many of the traditional input/output methods that can cause bottlenecks on modern motherboards. HT provides for serial point-to-point links between components at a variety of speeds and data widths, depending on the amount of bandwidth required.

HT has a couple of advantages over current bus technologies; firstly, HT links can provide considerable bandwidth and can be used on compatible chipsets to carry data between the CPU and the main memory as well as to connect the CPU to the Northbridge and Southbridge. Since HT links are point-to-point only, they provide a sort of highway for the data coming off the slower buses, by means of Hypertransport Bridges built into the Northbridge and Southbridge chips.

Hypertransport links use packets to carry data, similar to modern Ethernet technology, where the address of the data and the data itself is all transmitted on a single wire, rather than having separate address and data lines as conventional computer data buses do.

HT links can carry 3 times as much data on far fewer data lines than are required for conventional buses, simplifying motherboard design for manufacturers. The idea then, is that point-to-point Hypertransport links are built between the CPU and the chipset, allowing it to stream traffic from the various other buses onto this high bandwidth link and reduce I/O bottlenecks.

The Efficeon's hypertransport link runs at 400mhz with 8-bit links in each direction. This gives a total available bandwidth of 1.6GB/s.

Page 1: Transmeta Efficeon Mobile CPU Series
Page 2: Efficeon Form factor
Page 3: Efficeon and Built in AGP
Page 4: Efficeon chipsets