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Chapter 4 System Support
Compaq iPAQ Family of Internet Devices
First Edition - March 2000
4-10
AGP 2X Transfers
During AGP 2X transfers, clocking is basically the same as in 1X transfers except that the 66-
MHz CLK signal is used to qualify only the control signals. The data bytes are latched by an
additional strobe (AD_STBx) signal so that an 8-byte transfer occurs in one CLK cycle (Figure 4-
5). The first four bytes (DnA) are latched by the receiving agent on the falling edge of AD_STBx
and the second four bytes (DnB) are latched on the rising edge of AD_STBx. The signal level for
AGP 2X transfers may be 3.3 or 1.5 VDC.
Figure 4-5.
AGP 2X Data Transfer (Peak Transfer Rate: 532 MB/s)
T1 T2 T3 T4 T5 T6 T7
TRDY
-
GNT
-
CLK
AD_STBx
AD
D1A
D2A
D3A
D1B
D2B
D3B
D4A
D4B
ST0..2
00x
xxx
xxx
xxx
xxx
xxx