
NT6868A
Keyboard Controller
1
V2.1
Features
n
Built-in 6502 8-bit CPU
n
2 MHz CPU operation frequency
n
4K bytes of ROM
n
128 bytes of SRAM
n
One 8-bit programmable base timer with
1 - 256
μ
sec interval
n
29 programmable bi-directional I/O pins
n
3 LED direct sink pins with internal serial resistors
n
Mask optional for built-in RC oscillator with an
external resistor or external ceramic resonator applied
n
Watch-dog timer
n
Built-in power-on reset
n
Built-in low voltage reset
n
CMOS technology for low power consumption
n
Available in 40 pin DIP package and 40 pad CHIP
FORM
General Description
NT6868A is a single chip micro-controller for keyboard
applications. It incorporates a 6502 8-bit CPU core, 4K
bytes of ROM, and 128 bytes of RAM used as working
RAM and stack area. It also includes 29 programmable
bi-directional I/O pins and one 8-bit pre-loadable base
timer. Additionally, it includes a built-in low voltage
reset, a 4MHz RC oscillator that requires only a resistor
externally applied or a 4MHz ceramic resonator, and a
watch-dog timer that prevents system standstill.
Pin Configuration
GND
NC
DATA
CLK
P30
P31
P32
P33
P34
RESET
P11
P00
P01
P02
P03
P04
P05
P06
P07
P10
P17
P16
P15
P14
P13
P20
P21
P22
P23
P25
P24
P26
LED0
P27
LED1
V
DD
LED2
R/OSCO
OSCI
P12
N
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
25
24
23
22
21
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
Pad Configuration
NT6868AH
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
G
N
D
N
C
D
A
T
A
C
L
K
P
3
0
R
/
O
S
C
O
V
D
D
L
E
D
2
P31
P32
P33
P34
RESET
P00
P01
P02
P03
P04
P05
P20
P21
P22
P23
P24
P25
P26
P27
LED0
LED1
P
1
7
P
1
6
P
1
5
P
1
4
P
1
3
P
1
2
P
1
1
P
1
0
P
0
7
P
0
6
1
O
S
C
I