compatibility problems in Compatible Mode (the
control signals, by tradition, are specified
as open-collector), the drivers are dynamically
changed from open-collector to totem-pole. The
timing for the dynamic driver change is specified
in the IEEE 1284 Extended Capabilities Port
Protocol and ISA Interface Standard, Rev. 1.09,
Jan. 7, 1993, available from Microsoft. The
dynamic driver change must be implemented
properly to prevent glitching the outputs.
t6
t3
PDATA
t1
t2
t5
nSTROBE
t4
BUSY
Parameter
min
max
units
Notes
t1
t2
t3
t4
t5
t6
DATAValid to nSTROBEActive
nSTROBE Active Pulse Width
DATA Hold from nSTROBE Inactive
nSTROBE Active to BUSY Active
BUSY Inactive to nSTROBE Active
BUSY Inactive to PDATE Invalid
600
600
450
ns
ns
ns
ns
ns
ns
1
1
500
680
80
1. The data is held until BUSY goes inactive or for time t3, whichever is longer. This only
applies if another data transfer is pending. If no other data transfer ispending, the data
is held indefinitely.
FIGURE 19 - PARALLEL PORT FIFO TIMING
158
SMSC [ SMSC CORPORATION ]
