83C795 datasheet(20/136 Pages) SMSC

20 / 136 page

Mnemonic

Pin Number I/O

Description

LA17-LA23

13-19

I/O

PC LA ADDR E SS BUS. Advanced timing vers ion of s ys tem

address lines A23-A17 from PC/AT bus. T hese are not assumed to

be s table during the entire hos t cycle and are latched internally by

the BALE signal (falling edge). T hese s ignals are active high.

LLE D

131

I/O

T WPR LINK S T AT US . If valid data or Link Tes t puls es are received

on T PR+ / T PR-, LLE D is low (link s tatus OK). When no data or

Link Tes t puls es are received, LLE D is high. T he LLE D pin can

sink 4mA to drive an external LE D. T his pin als o functions as the

EER OM clock pin (formerly EES K) and functions as the s hift

control pin (formerly S HIF T IN) in scan mode.

M16CS

ME MOR Y 16 S E LE CT E D. Active low. Indicates to the PC/AT bus

that R AM access response is 16 bits wide.

MA15-MA10 139-144

ME MOR Y ADDR E S S LINE S . T hese pins bring out the DMA

addres s to memory or feed-through the hos t addres s as modified

for paging. When dumping R OM contents , thes e pins pres ent

ROM data bits :

MA15 R OM30 then R OM31

MA14 R OM28 then R OM29

. . .

MA00 R OM00 then R OM01

MA09/JMP9

MA08/JMP8

MA07/JMP7

MA06/JMP6

MA05/JMP5

MA04/JMP4

MA03/JMP3

MA02/JMP2

MA01/JMP1

MA00/JMP0

145

146

148

149

150

151

152

153

154

155

I/O

S ame as other MA lines except that during R E S E T, the drivers are

disabled and the INIT jumpers are read through thes e pins and

latched at the trailing edge of R E S E T. T hey are active high and are

pulled up weakly by internal res is tors (35k

Ω–150kΩ).

To s et a zero value on thes e pins , us e an external pull-down

res is tor of 3.6K

Ω.

MD7

MD6-MD0

158

3-9

I/O

ME MOR Y DAT A LINE S . T hese pins connect to the data pins of the

buffer R AM and the IPL or boot R OM.

ME MR

I/O

PC ME MOR Y R E AD for addres s es exceeding 1 M. Active low.

ME MW

I/O

PC ME MOR Y WR IT E for addres s es exceeding 1 M. Active low.

OS R

112

VCO BIAS R E S IS T OR . A res is tor from OS R to VCC bias es the

internal VCO current. Nominal value is 24.9K

Ω..

R AMOE

156

R AM OUT PUT E NABLE . Active low.

R AMWR

157

R AM WR IT E E NABLE . Active low.

RE S E T

I/O

SYST E M R E SE T. Active high.

TABLE 4-1. 83C795 PIN ASSIGNMENTS (CONT.)

PIN LIST

83C795

83C795 Datasheet(PDF) 20 Page - SMSC Corporation

83C795 Datasheet(HTML) 20 Page - SMSC 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

Datasheet Download

Link URL