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5-106 C141-E104-02EN
5.5.6 Series termination required for Ultra DMA
Series termination resistors are required at both the host and the device for
operation in any of the Ultra DMA Modes. The following table describes
recommended values for series termination at the host and the device.
Table 5.17 Recommended series termination for Ultra DMA
Signal Host Termination Device Termination
DIOR-:HDMARDY-:HSTROBE
22 Ω 82 Ω
DIOW-:STOP
22 Ω 82 Ω
CS0-, CS1-
33 Ω 82 Ω
DA0, DA1, DA2
33 Ω 82 Ω
DMACK-
22 Ω 82 Ω
DD15 through DD0
33 Ω 120 Ω (100 MHz)
DMARQ
82 Ω 22 Ω
INTRQ
82 Ω 22 Ω
IORDY:DDMARDY-:DSTROBE
82 Ω 22 Ω
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 Mode.
For signals also requiring a pull-up or pull-down resistor at the host see Figure 5.9.
Figure 5.9 Ultra DMA termination with pull-up or pull-down
Configuration of cable
For the configuration of the cable (common use of primary port and secondary
port), DMACK signal should not be used in common. It is not recommended to
use DIOR-, DIOW- and IORDY signal in common.
Vcc
DMARQ
IORDY