Terminology And Definitions - Intel VC820 - Desktop Board Motherboard Design Manual

Advanced System Bus Design
Section 2.9, "System Bus Design" on page 2-46
®
Intel 820 chipset based platforms. This chapter discusses more detail about the methodology used
to develop the guidelines.
system guidelines. This is a step-by-step methodology that Intel has successfully used to design
high performance desktop systems.
are applicable to this layout guideline.
contains more details and insights. The items in
recommendations in the step-by-step methodology. This section also includes equations that may
be used for reference.
3.1

Terminology and Definitions

Term
Aggressor
AGTL+
Bus Agent
Corner
®
Intel 820 Chipset Design Guide
Section 3.2, "AGTL+ Design Guidelines" on page 3-4
Section 3.3, "Theory" on page 3-15
Section 3.4, "More Details and Insight" on page 3-19
Definition
A network that transmits a coupled signal to another network is called the
aggressor network.
The processor system bus uses a bus technology called AGTL+, or Assisted
Gunning Transceiver Logic. AGTL+ buffers are open-drain and require pull-up
resistors for providing the high logic level and termination. The processor
AGTL+ output buffers differ from GTL+ buffers with the addition of an active
pMOS pull-up transistor to "assist" the pull-up resistors during the first clock of
a low-to-high voltage transition. Additionally, the processor Single Edge
Connector (S.E.C.) cartridge contains 56 Ω pull-up resistors to provide
termination at each bus load.
A component or group of components that, when combined, represent a single
load on the AGTL+ bus.
Describes how a component performs when all parameters that could impact
performance are adjusted to have the same impact on performance. Examples of
these parameters include variations in manufacturing process, operating
temperature, and operating voltage. The results in performance of an electronic
component that may change as a result of corners include (but are not limited
to): clock to output time, output driver edge rate, output drive current, and input
drive current. Discussion of the "slow" corner would mean having a component
operating at its slowest, weakest drive strength performance. Similar discussion
of the "fast" corner would mean having a component operating at its fastest,
strongest drive strength performance. Operation or simulation of a component at
its slow corner and fast corner is expected to bound the extremes between
slowest, weakest performance and fastest, strongest performance.
Advanced System Bus Design
describes the recommendations for designing
introduces the theories that
Section 3.4 expand on some of the rationale for the
3
discusses specific
3-1