IRCC SMSC Corporation, IRCC Datasheet - Page 75

• Manufacturer Part Number: IRCC
• Description: INFRARED COMMUNICATIONS CONTROLLER
• Manufacturer: SMSC Corporation

nSRDY
nSRDY can be driven by the IrCC to indicate that
an access cycle shorter than the standard I/O
cycle can be executed.
nSRDY & nNOWS can be used interchangeably.
nSRDY is enabled by the No Wait bit in SCE
The Interaction of nSRDY and IOCHRDY
nSRDY and IOCHRDY determine the three types
of ISA access cycles: no-wait-state cycle,
nSRDY
inactive
active
x
Table 32 - nSRDY and IOCHRDY Interaction
IOCHRDY
NOTE: the names
inactive
active
active
No Wait
nSRDY
FIGURE 48 - nSRDY TIMING
AEN
I/Ox
No-wait-state Cycle (shortest length)
Standard Cycle (mean length)
Ready Cycle (longest length)
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nSRDY goes active following the trailing edge of
the ISA I/O command and inactive following the
rising edge (Figure 48). nSRDY is suppressed
during DMA & refresh cycles, i.e. when AEN is
active, or when IOCHRDY is inactive. Zero Wait
State support is only available when the SCE is
enabled.
standard cycle, ready cycle (Table 32). NOTE:
An inactive IOCHRDY suppresses nSRDY.
DESCRIPTION