27256
The 27256 is an
Features:
●
●
●
●
●
32768 words
EPROM, which is a ultra-violet erasable and electrically programmable ROM.
X 8 bits
TTL compatible input/output
3
26
Al 3
+
5
V single power supply
25
Access time: 250
(max.)
5
A 9
28 pins (DIP)
6
23
A3 7
●
●
●
o
●
●
●
Terminal Functions:
AO to Al 4: Address input
Chip enable input
Output enable input
DO to D7: Data output
Program power supply
V..:
Power supply (+5 V)
Ground
8
21
9
o
10
1 9
11
1 6
12
17
2 13
16
G NO
13 03
Figure A-12. 27256 Pin Diagram
put
o
o
I
B u f f e r
Chip Enable
—
‘
Y- Decode
Y- Select
Address
‘
-
I
-
Memory
X - Decode
II
I
Mat rix
bit
I
Figure A-1 3. 27256
B l o c k D i a g r a m
Table A-5. 27256 Signal Status
Mode
OE
A 9
outputs
Read
L
L
x
D out
Output Disable
L
H
x
High Z
Standby
H
x
x
High Z
High Performance Program
L
H
x
D in
-
—
P r o g r a m V e r i f y
H
L
x
D out
O p t i o n a l V e r i f y
L
L
x
D out
P r o g r a m I n h i b i t
H
H
x
High Z
Identifier
L
VH
Code
NOTES:
X... Don’t care
3 .
=
– 0 . 6 -
7 V
2. VH = 12.OV
0.5V
4 .
=
– 0 . 6 - + 1 4 V
A-1 3
Содержание LQ-2550
Страница 1: ...L Q 2 5 5 0 TECHNICAL MANUAL EPSON ...
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