AM79C970 datasheet(30/168 Pages) AMD

30 / 168 page

P R E L I M I N A R Y

AMD

1-897

Am79C970

Master Initiated Termination

There are three scenarios besides normal completion of

a transaction where the PCnet-PCI controller will termi-

nate the cycles it produces on the PCI bus.

Preemption When FRAME is Deasserted

The PCnet-PCI controller will generate multiple address

phases during a single bus ownership period when it is

accessing the initialization block, the descriptor ring

entries and the data buffers in main memory.

FRAME is

deasserted in between two address phases. While

FRAME is deasserted, the central arbiter can remove

GNT to the PCnet-PCI controller at any time to service

another master. When

GNT is removed, the PCnet-PCI

controller will finish the current transfer and then release

the bus. It will keep

REQ asserted to regain bus owner-

ship as soon as possible.

18220C-12

FRAME

CLK

IRDY

TRDY

DEVSEL

REQ

GNT

1234567

ADDR

BE's

0111

PAR

DATA

DEVSEL is sampled by the PCnet-PCI controller.

Figure 10. Preemption When FRAME is Deasserted

AM79C970 数据表(PDF) 30 Page - Advanced Micro Devices

AM79C970 数据表(HTML) 30 Page - Advanced Micro Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

数据表下载