5.5 Ultra DMA Feature Set

i)The CRC generator polynomial is : G (X) = X16 + X12 + X5 + 1.

Note: Since no bit clock is available, the recommended approach for calculating CRC is to use a word clock derived from the bus strobe. The combinational logic shall then be equivalent to shifting sixteen bits serially through the generator polynomial where DD0 is shifted in first and DD15 is shifted in last.

5.5.6Series 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 5.28 Recommended series termination for Ultra DMA

Signal

Host Termination

Device Termination

 

 

 

DIOR-:HDMARDY-:HSTROBE

22 ohm

82 ohm

 

 

 

DIOW-:STOP

22 ohm

82 ohm

 

 

 

CS0-, CS1-

33 ohm

82 ohm

 

 

 

DA0, DA1, DA2

33 ohm

82 ohm

 

 

 

DMACK-

22 ohm

82 ohm

 

 

 

DD15 through DD0

33 ohm

22 ohm

 

 

 

DMARQ

82 ohm

22 ohm

 

 

 

INTRQ

82 ohm

22 ohm

 

 

 

IORDY:DDMARDY-:DSTROBE

82 ohm

22 ohm

 

 

 

RESET-

33 ohm

82 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 Mode. For signals also requiring a pull-up or pull-down resistor at the host see Figure 5.8.

Vcc

Figure 5.8 Ultra DMA termination with pull-up or pull-down

C141-E202-01EN

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Fujitsu MHU2100AT manual Series termination required for Ultra DMA, Recommended series termination for Ultra DMA, Diow-Stop