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REV.-A
A.1.4 HM27256G-25 EP-ROM
This EP-ROM is a ultra-violet erasable and electrically programmable ROM of 32 K-bytes.
Features
● Capacity of 32768 words X 8 bits
●
1/0 with TTL compatible
● Power supply
+5V DC
● Access time 250 ns
● 28 pins (DIP)
Terminal Functions
. AO - Al 4 Input address
● =
Chip enable
● OE
Output enable
● DO - D7 Input/Output data
Vcc
GND
Vpp
Vpv 1
26 Vcc
4 !2 2
n
A14
A7 3
26
413
46 1. 2S A 8
A5 5
2(, A 9
A4 6
23 A It
A3 7 22 TE
A2 e 21 AIO
A! 9
A o 10
19
D7
00 11
16
06
D 1 12
17
05
02 13
16 04
GND 14
15 03
Figure A-10. HM27256G-25 Pin Diagram
Dato Out Put
o
Do - D7
. . . . . . . .
?
6F— Output Enable -
?—iF—
output Buffer
Chip Enable
—
E : f ,
Y- Decode
1
Y- Select
Address
lnpW ‘-
AO
-
Ai4
Memory
X - Decode
Ce II
Mat rix
262144 bit
Figure A-1 1. HM27256G-25 EP-ROM Block Diagram
A-1 9