Datasheet

16 Chapter 1
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Personal Computer System Components
FIGURE 1.8 PCIe expansion slots
AMR Expansion Slots
As is always the case, Intel and other manufacturers are constantly looking for ways to
improve the production process. One lengthy process that would often slow down the pro-
duction of motherboards with integrated analog I/O functions was FCC certification. The
manufacturers developed a way of separating the analog circuitry, for example, modem and
analog audio, onto its own card. This allowed the analog circuitry to be separately certified
(it was its own expansion card), thus reducing time for FCC certification.
This slot and riser card technology was known as the Audio Modem Riser (AMR).
AMR’s 46-pin slots were once fairly common on many Intel motherboards, but technologies
including CNR and Advanced Communications Riser (ACR) are edging out AMR. In addi-
tion and despite FCC concerns, integrated components still appear to be enjoying the most
success comparatively. Figure 1.9 shows an example of an AMR slot.
CNR Expansion Slots
The Communications and Networking Riser (CNR) slots that can be found on some Intel
motherboards are a replacement for Intel’s AMR slots. One portion of these slots is the
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