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Rev. 1.00, 05/04, page 398 of 544
The timing of the LFRAME, LCLK, and LAD signals is shown in figures 15.2 and 15.3.
ADDRStart
LFRAME
LAD3–LAD0
Number of clocks
LCLK
TAR Sync Data TAR Start
Cycle type,
direction,
and size
114 12221
Figure 15.2 Typical LFRAME Timing
ADDRStart
LFRAME
LAD3–LAD0
LCLK
TAR Sync
Cycle type,
direction,
and size
Slave must stop driving
Too many Syncs
cause timeout
Master will
drive high
Figure 15.3 Abort Mechanism
15.4.3 A20 Gate
The A20 gate signal can mask address A20 to emulate an addressing mode used by personal
computers with an 8086*-family CPU. A regular-speed A20 gate signal can be output under
firmware control. The fast A20 gate function that is speeded up by hardware is enabled by setting
the FGA20E bit to 1 in HICR0.
Note: An Intel microprocessor