Intel 87C196CB, 8XC196NT user manual Table A-3. Signal Descriptions Continued

Models: 8XC196NT 87C196CB

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Table A-3. Signal Descriptions (Continued)

SIGNAL DESCRIPTIONS

 

 

Table A-3. Signal Descriptions (Continued)

Name

Type

 

 

Description

 

 

 

 

ADV#

O

Address Valid

 

 

 

This active-low output signal is asserted only during external memory

 

 

accesses. ADV# indicates that valid address information is available on the

 

 

system address/data bus. The signal remains low while a valid bus cycle is in

 

 

progress and is returned high as soon as the bus cycle completes.

 

 

An external latch can use this signal to demultiplex the address from the

 

 

address/data bus. A decoder can also use this signal to generate chip selects

 

 

for external memory.

 

 

ADV# is multiplexed with P5.0, SLPALE, and ALE.

AINC#

I

Auto Increment

 

 

 

During slave programming, this active-low input enables the auto-increment

 

 

feature. (Auto increment allows reading or writing of sequential OTPROM

 

 

locations, without requiring address transactions across the PBUS for each

 

 

read or write.) AINC# is sampled after each location is programmed or dumped.

 

 

If AINC# is asserted, the address is incremented and the next data word is

 

 

programmed or dumped.

 

 

AINC# is multiplexed with P2.4 and INTOUT#.

ALE

O

Address Latch Enable

 

 

This active-high output signal is asserted only during external memory cycles.

 

 

ALE signals the start of an external bus cycle and indicates that valid address

 

 

information is available on the system address/data bus. ALE differs from ADV#

 

 

in that it does not remain active during the entire bus cycle.

 

 

An external latch can use this signal to demultiplex address from the

 

 

address/data bus.

 

 

ALE is multiplexed with P5.0, SLPALE, and ADV#.

ANGND

GND

Analog Ground

 

 

 

ANGND must be connected for A/D converter and port 0 operation. ANGND

 

 

and VSS should be nominally at the same potential.

BHE#

O

Byte High Enable

 

 

During 16-bit bus cycles, this active-low output signal is asserted for word reads

 

 

and writes and high-byte reads and writes to external memory. BHE# indicates

 

 

that valid data is being transferred over the upper half of the system data bus.

 

 

Use BHE#, in conjunction with AD0, to determine which memory byte is being

 

 

transferred over the system bus:

 

 

BHE#

AD0

Byte(s) Accessed

 

 

0

0

both bytes

 

 

0

1

high byte only

 

 

1

0

low byte only

 

 

BHE# is multiplexed with P5.5 and WRH#.

 

 

The chip configuration register 0 (CCR0) determines whether this pin

 

 

functions as BHE# or WRH#. CCR0.2 = 1 selects BHE#; CCR0.2 = 0 selects

 

 

WRH#.

 

 

A-5

Page 126
Image 126
Intel 87C196CB, 8XC196NT user manual Table A-3. Signal Descriptions Continued