Philips Semiconductors

Product specification

74F646/A/74F648/A

Transceivers/registers

1990 Sep 25

6

The following examples demonstrate the four fundamental

bus–management functions that can be performed with the

74F646/646A and 74F648/648A. The select pins determine whether

data is stored or transferred through the device in real time. The

output enable pins determine the direction of the data flow.

BUS MANAGEMENT FUNCTIONS

REAL TIME BUS TRANSFER

BUS B TO BUS A

REAL TIME BUS TRANSFER

BUS A TO BUS B

STORAGE FROM

A, B, OR A AND B

TRANSFER STORED DATA

TO A AND/OR B

OE DIR CPAB CPBA SAB SBA

LL

X

X

X

L

BUS A

BUS A

BUS A

BUS A

BUS B

BUS B

BUS B

BUS B

OE DIR CPAB CPBA SAB SBA

LH

X

X

L

X

OE DIR CPAB CPBA SAB SBA

XX

↑

XX

X

XX

X

↑

XX

HX

↑↑

XX

OE DIR CPAB CPBA SAB SBA

L

L

X

H or L

X

H

L

H

H or L

X

H

X

SF00392