AM79C976 datasheet(178/309 Pages) AMD

178 / 309 page

178

Am79C976

8/01/00

P R E L I M INARY

RES

Reserved Location. Written as

zero and read as undefined.

TXDPOLL

Disable Transmit Polling. If TXD-

POLL is set, the Buffer Manage-

ment Unit will disable transmit

polling. Likewise, if TXDPOLL is

cleared, automatic transmit poll-

ing is enabled. If TXDPOLL is set,

TDMD bit in CSR0 must be set in

order to initiate a manual poll of a

transmit descriptor. Transmit de-

scriptor polling will not take place

if TXON is reset. Transmit polling

will take place following Receive

activities.

Read/Write

accessible.

TXD-

POLL is cleared by H_RESET or

S_RESET and is unaffected by

the STOP bit.

APAD_XMT Auto Pad Transmit. When set,

APAD_XMT enables the auto-

matic padding feature. Transmit

frames will be padded to extend

them to 64 bytes including FCS.

The FCS is calculated for the en-

tire frame, including pad, and ap-

pended after the pad field. When

the auto padding logic modifies a

frame, a valid FCS field will be

appended to the frame, regard-

less of the state of the DXMTFCS

bit (CSR15, bit 3) and of the

ADD_FCS bit in the transmit de-

scriptor.

Read/Write

accessible.

APAD_XMT

cleared

H_RESET or S_RESET and is

unaffected by the STOP bit.

ASTRP_RCVAuto Strip Receive. When set,

ASTRP_RCV enables the auto-

matic pad stripping feature. The

pad and FCS fields will be

stripped from receive frames and

not placed in the FIFO.

Read/Write

accessible.

ASTRP_RCV

cleared

H_RESET or S_RESET and is

unaffected by the STOP bit.

MFCO

Obsolete function. Writing has no

effect. Read as undefined.

MFCOM

Obsolete function. Writing has no

effect. Read as undefined.

UINTCMD

User

Interrupt

Command.

UINTCMD can be used by the

host to generate an interrupt un

related to any network activity.

Writing a 1 to this bit causes

UINT to be set to 1, which in turn

causes INTA to be asserted if in-

terrupts are enabled.

Read/Write accessible. UINTC-

MD is always read as 0.

UINT

User Interrupt. UINT is set by the

Am79C976 controller after the

host has issued a user interrupt

command by setting UINTCMD

(CSR4, bit 7) to 1.

Read/Write accessible. UINT is

cleared by the host by writing a 1.

Writing a 0 has no effect. UINT is

cleared

H_RESET

S_RESET or by setting the STOP

bit.

RCVCCO

Obsolete function. Writing has no

effect. Read as undefined.

RCVCCOM Obsolete function. Writing has no

effect. Read as undefined.

TXSTRT

Transmit Start status is set by the

Am79C976 controller whenever it

begins transmission of a frame.

When TXSTRT is set, INTA is as-

serted if IENA is 1 and the mask

bit TXSTRTM is 0.

Read/Write accessible. TXSTRT

is cleared by the host by writing a

1. Writing a 0 has no effect. TX-

STRT is cleared by H_RESET,

S_RESET, or by setting the

STOP bit.

TXSTRTM

Transmit

Start

Mask.

TX-

STRTM is set, the TXSTRT bit

will be masked and unable to set

the INTR bit.

Read/Write

accessible.

TX-

STRTM is set to 1 by H_RESET

or S_RESET and is not affected

by the STOP bit.

AM79C976 датащи(PDF) 178 Page - Advanced Micro Devices

AM79C976 датащи(HTML) 178 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

датащи скачать

ссылки URL