Epson LQ-2550 Technical Manual page 259

A.1.1.5 HM65256Bsp-15
The HM65256BSp-15 is a CMOS pseudo static RAM, and features
compatible input/output.
Features:
32768 words X 8 bits
+5 V single power supply
28 pins (DIP)
Terminal Functions:
AO to Al 4: Address input
. WE: Write enable
. ~: Output enable input
1/00 to 1/07: Data input/output
GND: Ground
L
L
L
H
H
NOTE: X Don't care
- - - - - - - - -
I
1
Figure A-1 5. HM65256BSP-15 Block Diagram
Table A-6. HM65256BSP-15 Signal Status
OE WE
H
L
x L
H H
x
L
X
low power consumption and TTL
1 / 0 0
1 / 0 2
Figure A-14. HM65256BSP-15 Pin Diagram
I
I
- - - - - - - -
— - 1
Low Z
High Z
Z
High
High Z
High Z
A-1 4
4
A 9
2 2
21
10
1/06
1/0s
12
16
1 / 0 4
14
1 / 0 1
1 1
4
I
Function
Read
Write
—
Refresh
Standby