VIA Apollo KT333 Chipset White Paper
VIA Apollo KT333 Chipset
High performance DDR333 chipset platform for the
AMD Athlon™ XP processor
Page 1VIA Apollo KT333 Chipset White Paper
Introduction
The VIA Apollo KT333 is a core logic chipset solution that elevates the performance
of AMD Athlon™ XP based systems to heights never scaled before. Building on the
success of the award-winning VIA Apollo KT266A platform, the implementation of
DDR333 memory support in the VIA Apollo KT333 adds 25% more memory
bandwidth delivering breathtaking application performance, across the board. The
flexibility of V-MAP architecture means the VIA Apollo KT333 is pin to pin compatible
with the previous generation VIA Apollo KT266A, enabling it to leverage the huge
choice of motherboard configurations already developed, ensuring stability and
reliability.
In addition, the VIA Apollo KT333 features a choice of V-MAP South Bridge options,
offering a market leading array of networking and communication features, including
Ultra ATA-133, integrated 3Com® Ethernet MAC, and high-speed V-Link chip to chip
interface.
The launch of the VIA Apollo KT333 further extends the leadership role that VIA has
played in enabling rapid industry wide transitions to higher bandwidth memory
technologies that enable OEMs and SIs to address a performance hungry market and
support the today’s and tomorrow’s most demanding applications. It achieves this
through the implementation of the following key technologies:
• DDR200/266/333 SDRAM Support: The VIA Apollo KT333 features the
world’s fastest single channel memory controller, designed for exceptionally
high performance. In addition to DDR200/266 memory, the VIA Apollo KT333
also supports new high speed DDR333 SDRAM that conforms with the JEDEC
standard. DDR333 SDRAM provides lightning fast access to system memory
and can reach a peak bandwidth of 2.7GB/sec, 25% greater than the KT266A,
to enable the full performance potential of the fastest AMD Athlon™ XP
processors to be harnessed.
• ATA-133 IDE Interface: ATA-133 FastDrive™, integrated into the VT8233A
South Bridge, is the fastest IDE interface currently available and meets
today’s ever increasing data transfer requirements offering shorter access
times and greater performance in a huge variety of everyday applications
including audio, video & gaming.
• V-MAP: The VIA Modular Architecture Platform offers a balance of reliability
and flexibility. Reliability comes from using proven, modular components and
evolutionary design principles in enabling the VIA Apollo KT333 to share the
best characteristics of award winning previous generation products like the
VIA Apollo KT266A. Flexibility comes from the North Bridge pin compatible
with the KT266A and the industry’s best choice of pin compatible VT8233
series South Bridge options enabling a variety of system configurations and
price points based on the same mainboard design.
• High-Speed V-Link Hub Architecture: The VIA Apollo KT333A makes use
of VIA’s V-Link Hub Architecture, which provides a dedicated 266MB/s bus
between the north and south bridge. Less advanced chipsets use the 132MB/s
PCI bus as a link, which must be shared with all PCI peripherals.
Page 2VIA Apollo KT333 Chipset White Paper
• 200/266MHz Front Side Bus Settings: The VIA Apollo KT266A supports
the AMD Athlon/Duron S2K system bus, running at up to an effective 266MHz.
• AGP4X/2X Support: Providing up to 1GB/s in graphics bandwidth with
AGP4X technology, the VIA Apollo KT333 supports the latest in video card
technology. Additionally, it does not sacrifice AGP2X compatibility like less
advanced chipsets, allowing low cost graphics products to be paired with AMD
Duron™ systems for very keenly priced everyday computing.
This white paper describes the features of the VIA Apollo KT333 chipset as well as
the combination of performance and cost efficiency that enables next generation
computing for mainstream and value desktops, workstations, and servers based on
the AMD Athlon™ XP processor.
DDR333: The Power of Evolution
VIA Technologies, Inc. has been instrumental in driving new memory technologies to
the market by being the first company to offer PC133 based chipsets to the
marketplace, and the first company offer DDR SDRAM based chipsets for Socket 370
(Intel® Pentium® III), Socket 423/478 (Intel® Pentium® 4) and Socket A (AMD
Athlon™ and AMD Duron™) platforms.
DDR SDRAM was developed to keep pace with newer, more powerful PC processors
like the AMD Athlon™ XP and Intel® Pentium® 4 which require faster access to the
system memory to deliver to their full performance potential. Compared to
PC100/133, DDR doubles the effective clock rate by transferring data on both the
rising and falling edges of the clock. Also, due to its evolutionary, parallel
technology, the latency of DDR is quite low compared to competing serial memory
technologies like RDRAM.
All grades of DDR SDRAM operate at 2.5 volts, as opposed to 3.3V for PC100 and
PC133. This lowered voltage allows DDR to penetrate power sensitive applications,
such as notebooks and 1U servers. Lowered power consumption translates directly to
lowered heat dissipation, again increasing the effectiveness of DDR in mobile and
server applications.
These basic specifications of SDRAM technologies are summarised below.
Clock Rate Effective Memory bandwidth Voltage
Clock Rate
PC100 100MHz 100MHz 0.8GB/sec 3.3
PC133 133MHz 133MHz 1.05GB/sec 3.3
DDR200 100MHz 200MHz 1.6GB/sec 2.5
DDR266 133MHz 266MHz 2.1GB/sec 2.5
DDR333 167MHz 333MHz 2.7GB/sec 2.5
DDR333 offers the greatest memory bandwidth yet, a 25% increase over DDR266,
delivering performance benefits in every type of application but especially in memory
intensive 3D graphics and gaming. With new and more demanding software
applications and faster processors being developed all the time, the extra bandwidth
gives DDR333 based systems much needed performance headroom.
Page 3VIA Apollo KT333 Chipset White Paper
VIA DDR333 Validation Programme
To ensure the reliability and stability of DDR333 memory modules and devices, VIA
is conducting an independent validation programme in conjunction with Advanced
Validation Labs and SMART Modular Technology. The VIA DDR independent validation
programme is essential in making the transition to new memory technologies smooth
and ultimately successful.
The validation process will ensure DDR333 modules and devices are fully compatible

VIA KT333是一款由台湾 VIA Technologies, Inc.（威盛科技股份有限公司）在20世纪90年代末期推出的经典计算机主板芯片组。KT333是K8架构下的一个成员，专为AMD K6-2、 Athlon 以及后来的Athlon XP等Socket 754接口的微处理器设计。 这款芯片组主要包括南北桥两部分功能：北桥负责与CPU、内存控制器、IDE/ATA以及AGP接口等核心系统组件的连接，南桥则主要管理PCI总线、USB、IDE硬盘、软驱、COM和LPT等I/O设备。其中，KT333芯片组特别强调了对高速AGP 4x/8x图形加速接口的支持，使得当时的PC平台能够流畅运行当时流行的高性能显卡，从而显著提升了系统的3D图形处理性能。 KT333芯片组还提供了16位的内存控制器，支持最大到1GB DDR SDRAM的工作，对于当时的主流配置来说具有较高的兼容性和扩展性。此外，它采用了标准的PC97南桥接口规范，便于与其他周边芯片和设备无缝集成。 总之，VIA KT333以其优秀的性能和广泛的应用范围，在当时的个人电脑市场中占据了重要地位，推动了计算机硬件技术的发展，特别是在入门级和中端市场上非常受欢迎。