STPC0375BTC3 datasheet(17/51 Pages) STMICROELECTRONICS

17 / 51 page

PIN DESCRIPTION

17/51

Issue 1.2

LA[22]/SCS1#

Unlatched Address (ISA)/Second-

ary Chip Select (IDE)

This pin has two functions, depending on whether

the ISA bus is active or the IDE bus is active.

When the ISA bus is active, this pins is ISA Bus

unlatched address bit 22 for 16-bit devices. When

ISA bus is accessed by any cycle initiated from

PCI bus, this pin is in output mode. When an ISA

bus master owns the bus, this pins is in input

mode.

When the IDE bus is active, this signals is used as

the active high secondary slave IDE chip select

signal. This signal is to be externally ANDed with

the ISAOE# signal before driving the IDE devices

to guarantee it is active only when ISA bus is idle.

LA[21]/PCS3#

Unlatched Address (ISA)/Primary

Chip Select (IDE). This pin has two functions, de-

pending on whether the ISA bus is active or the

IDE bus is active.

When the ISA bus is active, this pins is ISA Bus

unlatched address bit 21 for 16-bit devices. When

ISA bus is accessed by any cycle initiated from

PCI bus, this pin is in output mode. When an ISA-

bus master owns the bus, this pins is in input

mode.

When the IDE bus is active, this signals is used as

the active high primary slave IDE chip select sig-

nal. This signal is to be externally NANDed with

the ISAOE# signal before driving the IDE devices

to guarantee it is active only when ISA bus is idle.

LA[20]/PCS1#

Unlatched Address (ISA)/Primary

Chip Select (IDE). This pin has two functions, de-

pending on whether the ISA bus is active or the

IDE bus is active.

When the ISA bus is active, this pins is ISA Bus

unlatched address bit 20 for 16-bit devices. When

ISA bus is accessed by any cycle initiated from

PCI bus, this pin is in output mode. When an ISA

bus master owns the bus, this pins is in input

mode.

When the IDE bus is active, this signals is used as

the active high primary slave IDE chip select sig-

nal. This signal is to be externally NANDed with

the ISAOE# signal before driving the IDE devices

to guarantee it is active only when ISA bus is idle.

LA[19:17]/DA[2:0]

Unlatched Address (ISA)/Ad-

dress (IDE). These pins are multi-function pins.

They are used as the ISA bus unlatched address

bits [19:17] for ISA bus or the three address bits

for the IDE bus devices.

When used by the ISA bus, these pins are ISA

Bus unlatched address bits 19-17 on 16-bit devic-

es. When ISA bus is accessed by any cycle initiat-

ed from the PCI bus, these pins are in output

mode. When an ISA bus master owns the bus,

these pins are tristated.

For IDE devices, these signals are used as the

DA[2:0] and are connected to DA[2:0] of IDE de-

vices directly or through a buffer. If the toggling of

signals are to be masked during ISA bus cycles,

they can be externally ORed before being con-

nected to the IDE devices.

SA[19:8]/DD[11:0]

Unlatched Address (ISA)/Data

Bus (IDE). These are multifunction pins. When the

ISA bus is active, they are used as the ISA bus

system address bits 19-8. When the IDE bus is ac-

tive, they serve as IDE signals DD[11:0].

These pins are used as an input when an ISA bus

master owns the bus and are outputs at all other

times.

IDE devices are connected to SA[19:8] directlyand

ISA bus is connected to these pins through two

LS245 transceivers. The OE of the transceivers

are connected to ISAOE# and DIR is connected to

MASTER#. A bus signals of the transceivers are

connected to CPC and IDE DD bus and B bus sig-

nals are connected to ISA SA bus.

DD[15:12]

Databus (IDE). The high 4 bits of the

IDE databus are combined with several of the X-

bus lines. Refer to the following section for X-bus

pins for further information.

SA[7:0]

ISA Bus address bits [7:0]. These are the

8 low bits of the system address bus of ISA on 8-

bit slot. These pins are used as an input when an

ISA bus master owns the bus and are outputs at

all other times.

SD[15:0]

I/O Data Bus (ISA). These pins are the

external databus to the ISA bus.

STPC0375BTC3 数据表(PDF) 17 Page - STMicroelectronics

STPC0375BTC3 数据表(HTML) 17 Page - STMicroelectronics

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

数据表下载

链接网址

STPC0375BTC3 数据表(PDF) 17 Page - STMicroelectronics

STPC0375BTC3 数据表(HTML) 17 Page - STMicroelectronics

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

数据表 下载

链接网址

数据表下载