UPD6600A NEC, UPD6600A Datasheet - Page 5

• Manufacturer Part Number: UPD6600A
• Description: 4-BIT SINGLE-CHIP MICROCONTROLLER FOR REMOTE CONTROL TRANSMISSION
• Manufacturer: NEC

3.
4.
data memory is processed in 8-bit units. R
Caution
The program memory (ROM) is configured in 10 bits steps. It is addressed by the program counter.
Program and table data are stored in the program memory.
The data memory is a RAM of 32 words
After power application, the RAM will be undefined. The RAM retains the previous data on reset.
0FFH
1FFH
000H
100H
PROGRAM MEMORY (ROM) ……… 512 STEPS
DATA MEMORY (RAM) ……… 32 WORDS
Avoid using the RAM areas R
are also used as stack memory areas (to prevent program hang-up in case the value of the SP is
destroyed due to some reason such as noise).
When using these RAM areas as general-purpose RAM areas, be sure to include stack pointer
checking in the main routine.
(a)
PD6600A
Figure 4-1. Data Memory Organization
Figure 3-1. Program Memory Map
1
D
, R
0
may be used as the data pointer for the ROM.
E
5 bits. The data memory stores processing data. In some cases, the
, and R
1002 STEPS
0
F
in a CALL routine as much as possible because these areas
3EAH
0FFH
1FFH
2FFH
3E9H
3FFH
000H
100H
200H
300H
5 BITS
R
R
R
R
. .
.
. .
.
C
B
F
0
10 BITS
10 BITS :
(b)
SP–3
SP–2
SP–1
SP–0
:
PD6124A
PD6600A
PD6124A
PD6124A, 6600A
Test program
area
5
0
0
1
1
0
0
1
1