4

IP2 Chip

The registers which control IP_c and IP_d are not used on the 200/300- Series MVME172.

ADR/SIZ

 

$FFFBC030, $48, $60, $78 (32 bits each)

 

 

 

 

 

 

BIT

31...24

 

23

 

0

 

 

 

 

 

 

NAME

0

 

 

DMA_a Byte Counter

 

 

 

 

 

 

 

OPER

R

 

 

R/W

 

 

 

 

 

 

 

RESET

 

 

 

0 R

 

 

 

 

 

 

 

DMA Table Address Counter

In the command chaining mode, this counter should be loaded by the processor with the starting address of the list of commands. Note that the command packets in local bus memory must always be 16-byte aligned. That is, the starting address of any command packet must have the least significant nibble of the address set to a zero. If the Table Address Counter is initialized with a value where the four least significant bits are not a zero, the logic will interpret it as a halt condition and the command chaining process will not start. Therefore the entry in the last command packet which is loaded into the Table Address Counter should have one or more of these address bits set to a one to halt the command chaining process.

The registers which control IP_c and IP_d are not used on the 200/300- Series MVME172.

ADR/SIZ

 

$FFFBC034, $4C, $64, $7C (32 bits each)

 

 

 

 

 

BIT

31

...

0

 

 

 

 

NAME

 

DMA Table Address Counter

 

 

 

 

 

OPER

 

R/W

 

 

 

 

 

RESET

 

0 R

 

 

 

 

 

4-42

Computer Group Literature Center Web Site

Page 278
Image 278
Motorola MVME172 manual DMA Table Address Counter