Datasheet


Ultra DMA Electrical Requirements

Host
and
Card
signal
capacitance
limits
for
Ultra
DMA
operation
The host interface signal capacitance at the host connector shall be a maximum of 25 pF for each signal as measured at
1 MHz. The card interface signal capacitanc e at the card connector shall be a maximum of 20 pF for each signal as
measured at 1 MHz.

Series
termination
required
for
Ultra
DMA
operation
Series termination resistors are required at both the host and the card for operation in any of the Ultra DMA modes. Table
13 describes typical values for series termination at the host.
Signal Host Termination
-IORD ( -HDMARDY, HSTROBE) 22 ohm
-IOWR (STOP) 22 ohm
-CS0, -CS1 33 ohm
A00, A01, A02 33 ohm
-DMACK 22 ohm
D15 through D00 33 ohm
DMARQ 82 ohm
INTRQ 82 ohm
IORDY (-DDMARDY, DSTROBE) 82 ohm
-RESET 33 ohm
NOTE − Only those signals requiring termination are listed in this table. If a signal is
not listed, series termination is not required for operation in an Ultra DMA mod e.
Below table show signals also requiring a pull-up or p ull-down resistor at the host.
The a ctual termination values should be selected to compensate for transceiver and
trace impedance to match the characteristic cable impedance
Table: Typical Series Termination for Ultra DMA