HD74HC670 Datasheet, PDF (2/9 Pages) Hitachi Semiconductor – 4-by-4 Register File (with 3-state outputs)

HD74HC670
Function Table
Write Inputs
WB
WA
GW
L
L
L
L
H
L
H
L
L
H
H
L
X
X
H
0
Q=D
Q0
Q0
Q0
Q0
1
Q0
Q=D
Q0
Q0
Q0
Word
2
Q0
Q0
Q=D
Q0
Q0
3
Q0
Q0
Q0
Q=D
Q0
Read Inputs
Outputs
RB
RA
GR
Q1
Q2
Q3
Q4
L
L
L
W0 B1
W0 B2
W0 B3
W0 B4
L
H
L
W1 B1
W1 B2
W1 B3
W1 B4
H
L
L
W2 B1
W2 B2
W2 B3
W2 B4
H
H
L
W3 B1
W3 B2
W3 B3
W3 B4
X
X
H
Z
Z
Z
Z
H
: high level
L
: low level
X
: irrelevant
Z
: high impedance (off)
(Q = D): The four selected internal flip-flop outputs will assume the states applied to the four external data inputs.
Q0 : The level of Q before the indicated input conditions were established.
W0 B1 : The first bit of word 0, etc.
Pin Arrangement
D2 1
Data D3 2
D4 3
RB 4
Read
select
RA 5
Q4 6
Outputs
Q3 7
GND 8
D3
D2
D1
D4
WA
RB
WB
RA
CW
Q4
CR
Q3 _Q2 Q1
16 VCC
15
Data
D1
14 WA
13 WB
Write
select
12 Write
Enable
11 Read
10 Q1
9 Q2
Outputs
(Top view)
Rev.2.00 Mar 30, 2006 page 2 of 8