Motorola MVME172 manual DMA Arbitration Control Register

Models: MVME172

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Programming Model

DMA Arbitration Control Register

The DMA arbitration control register contents determine whether a fixed or fair arbitration algorithm is used to determine how the MC68060 local bus is attached to the internal DMA data paths.

 

ADR/SIZ

 

 

 

 

 

$FFFBC01E (8 bits)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BIT

7

6

5

 

4

3

 

2

1

 

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NAME

0

0

0

 

0

0

 

ROTAT

 

PRI1

 

PRI0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OPER

 

R

R

 

R

 

R

 

R

 

R/W

 

R/W

 

R/W

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RESET

 

0 R

0 R

 

0 R

 

0 R

 

0 R

 

0 R

 

0 R

 

0 R

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ROTAT

ROTAT set to a zero enables a rotating arbitration method

 

 

 

 

where each DMAC has equal access to the MC68060

 

 

 

 

local bus. If ROTAT is set to a one, the priority is fixed

 

 

 

 

according to the following table

 

 

 

 

 

 

PRI1,PRI0 Fixed priority assignment is defined by the following

 

 

 

 

tables.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PRI1 - PRI0

 

 

Priority with one DMA channel at IP sockets a, b, c, & d

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Highest

 

Next Highest

 

Next Lowest

 

Lowest

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

00

 

DMA_a

 

 

DMA_b

 

 

DMA_c

 

DMA_d

 

 

 

 

 

 

 

 

 

 

01

 

DMA_b

 

 

DMA_c

 

DMA_d

 

DMA_a

 

 

 

 

 

 

 

 

 

 

 

10

 

DMA_c

 

 

DMA_d

 

 

DMA_a

 

DMA_b

 

 

 

 

 

 

 

 

 

 

11

 

DMA_d

 

 

DMA_a

 

DMA_b

 

DMA_c

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PRI1 - PRI0

 

 

Priority with two DMA channel at IP sockets a and c

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Highest

 

Next Highest

 

Next Lowest

 

Lowest

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

00

 

DMA_a chan 0

 

DMA_a chan 1

 

DMA_c chan 0

 

DMA_c chan 1

 

 

 

 

 

 

 

 

 

01

 

DMA_a chan 1

 

DMA_c chan 0

 

DMA_c chan 1

 

DMA_a chan 0

 

 

 

 

 

 

 

 

 

10

 

DMA_c chan 0

 

DMA_c chan 1

 

DMA_a chan 0

 

DMA_a chan 1

 

 

 

 

 

 

 

 

 

11

 

DMA_c chan 1

 

DMA_a chan 0

 

DMA_a chan 1

 

DMA_c chan 0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4

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Motorola MVME172 manual DMA Arbitration Control Register, Where each Dmac has equal access to the MC68060