82374EB datasheet(73/208 Pages) INTEL

73 / 208 page

82374EB82374SB

3224 CBPFFCLEAR BYTE POINTER FLIP FLOP REGISTER

00ChChannels 0-3

0D8hChannels 4-7

Default Value

xxh

Attribute

Write Only

Size

8 Bits

This command is executed prior to writing or reading new address or word count information to the DMA This

initializes the flip-flop to a known state so that subsequent accesses to register contents by the microproces-

sor will address upper and lower bytes in the correct sequence

The Clear Byte Pointer command clears the internal latch used to address the upper or lower byte of the 16-bit

address and Word Count registers The latch is also cleared at power on by reset and by the Master Clear

command The Host CPU may read or write a 16-bit DMA controller register by performing two consecutive

accesses to the IO port The Clear Byte Pointer command precedes the first access The first IO write to a

cant byte

When the Host CPU is reading or writing DMA registers two Byte Pointer Flip-Flops are used one for Chan-

nels 0-3 and one for Channels 4-7 Both of these act independently There are separate software commands

for clearing each of them (0Ch for Channels 0-3 0D8h for Channels 4-7)

Bit

Description

Clear Byte Pointer FF

No specific pattern Command enabled with a write to the IO port address

3225 DMCDMA MASTER CLEAR REGISTER

00DhChannels 0-3

0DAhChannels 4-7

Default Value

xxh

Attribute

Write Only

Size

8 Bits

This software instruction has the same effect as the hardware Reset The Command Status Request and

Internal FirstLast Flip-Flop registers are cleared and the Mask register is set The DMA controller will enter

the idle cycle

There are two independent Master Clear Commands 0Dh which acts on Channels 0-3 and 0DAh which acts

on Channels 4-7

Bit

Description

Master Clear

No specific pattern Command enabled with a write to the IO port address

82374EB датащи(PDF) 73 Page - Intel Corporation

82374EB датащи(HTML) 73 Page - Intel Corporation

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

датащи скачать

ссылки URL