Next-Generation Personal Computers Coming into Sight
October 29, 2001 (TOKYO) -- Personal computers are on the road toward higher-performance specifications with very different types of CPUs, buses and memories to be implemented in the coming years.
In summary, in the next-generation PCs, new CPUs will be equipped with a virtual processor function, and the PCI bus will be replaced with a higher-speed serial interface. As for the memory, they will also see major changes, with the introduction of DDR SDRAMs in place of the current diffusion type of SDRAM. (See figure)
CPU Driven for Higher Utilization Rate by Multi-CPU Technology
A conventional means of enhancing the performance of a CPU is to realize higher operating frequencies. However, engineers are seeing an end to this strategy. At higher operating frequencies, CPUs will consume more power, and this results in a CPU releasing large amounts of heat.
In order to avoid this, new PCs will be equipped with technology to enhance efficiency in using a CPU. One example is the Hyper-Threading Technology announced by Intel Corp. at the Intel Developer Forum (IDF) held in August.
This is a virtual multi-processor technology that makes an OS assume that two CPUs are working, while actually only one CPU is present. This is realized by making the program process in two threads concurrently in the CPU, and to lesson the resting time of the CPU. This will improve the utilization rate of a CPU. Intel plans to implement the Hyper-Threading Technology in CPUs for servers in 2002, and then it will be introduced in desktops and notebook PCs.
Intel also announced at the IDF that it has been working out on a new type of CPU for notebook PCs, a development codenamed "Banias," where power consumption is its key feature. Intel plans to start shipping this CPU in the first half of 2003. Intel has not made public the specifications of the CPU, but it is designed to suppress power consumption by loading a function that can control power by detecting circuits in non-operating status at a certain time and to halt them, and some improvements and optimization of the circuit will be made. Furthermore, it will introduce a technology to enhance a utilization rate of the CPU by linking two instructions to the process as one instruction.
PCI Bus Taken over by High-Speed Serial Bus
PCI buses will be taken over between 2003 and 2004 by serial interfaces working at a higher speed. Due to restrictions on their speeds, PCI buses cannot handle full operations of CPUs and peripherals while those devices are being improved in terms of performance and speed.
With this view, Intel has been pursuing standardization of Third Generation I/O (3GIO) as the third standard following ISA and PCI. And now, 3GIO is gaining wider support as the next standard. For example, the PCI Special Interest Group (PCI-SIG), which is promoting standardization of PCI buses, announced in August its adoption of 3GIO as part of its next-generation standard PCI3.0.
In 3GIO, two serial transfer paths in one direction are bundled together so as to be handled as the basic path. The operating frequency of the serial transfer paths initially will be set at 2.5GHz, enabling one-direction transfer at 200MB per second. Intel assures that the operating frequency can be upgraded to 10GHz in the future. As the OS qualifies a 3GIO bus as a PCI bus, there is no need to modify the OS or PCI-specific device drivers.
3GIO matches a chip with a device in a one-to-one connection. This method allows a device to communicate, while another device is in the process of handling other communications, without causing a signal to be reflected at a branch point.
Future PCs will use a serial interface for connection to a hard disk. The trend is moving to the next-generation ATA standard, Serial ATA 1.0, from the current parallel data transfer method based on UltraATA/100. Serial ATA is due to start with an operating frequency at 1.5GHz and a data transfer speed at 150MB per second. But, they will be enhanced in a next version of the standard to 3GHz and 150MB per second, respectively. This leads to thinner cables and easier handling as well as hot swapping.
DDR SDRAM as Next Diffusion Type of Memory
The mainstream memory will finally be changed, that is, a shift will be made to a newer high-speed memory.
Intel plans to ship a Pentium 4-specific chipset compliant with DDR SDRAM early in 2002. Rambus DRAMs have been suffering due to their high prices, where they are competing with DDR SDRAMs, which is regarded as the front-runner. AMD has been making efforts to penetrate the DDR SDRAM market as a main PC component.
In 1996, Intel positioned the Rambus DRAM as the next-generation memory. Thus, at first, the only Pentium 4-specific chipset that was made ready for the market was the i850, designed specifically for Rambus DRAM memory.
Today, few PCs provided by major makers are equipped with DDR memory. However, chances are high for DDR to become the mainstream of next-generation memory, because Intel has decided to support DDR memories.
The two types, PC2100 and PC1600, are apparent candidates that will support DDR-enabled i845 CPU coming on the market in 2002. The PC2100 type features a data transfer speed at 2.1GB per second, which is faster than the speed of Rambus memory at 1.6GB per second. However, because DDR is used as an add-on memory in terms of single units, its total performance falls short of that of using Rambus memory which would reach 3.2GB per second. Therefore, it is highly possible that DDR-enabled i845 cannot surpass the performance of i850. Consequently, Rambus memory will be applied to high-end machines, and DDR to mid-range and low-end machines.
And yet, DDR SDRAM might have some problems, such as compatibility. Specifically, DDR has signal lines split at each slot before connection to each module. In this wiring method, signal reflection can be generated, causing malfunctions. Intel, being aware of this issue, has requested JEDEC, a standardization body concerned with memory, to add necessary conditions to the DDR specifications.
We will see further speedups of DDR and Rambus memory (refer to the figure above). The chip specifications of DDR will be upgraded from DDR I to DDR II by 2003, setting higher operating frequencies. They have already started to formulate DDR III specifications, targeting even higher speeds.
On the other hand, higher transfer speeds of Rambus memory will be pursued by making the operating frequency higher and the bus width wider. In this scheme, the PC 1066 type to be shipped next year will transfer data at 2.1GB per second on a 16-bit bus. The PC 1200, projected to go on the market in 2005, will work at 9.6GB per second on a 64-bit bus. However, many questions still remain unanswered.
Figure2: Mega change inside the PC: CPU, Memory, Bus,HDD
(Masahiro Kurata, Staff Editor, Nikkei Personal Computing) |
