upd17240 Renesas Electronics Corporation., upd17240 Datasheet - Page 20

• Manufacturer Part Number: upd17240
• Description: 4-bit Single-chip Microcontrollers For Small General-purpose Infrared Remote Control Transmitters
• Manufacturer: Renesas Electronics Corporation.

2.3
later) when a subroutine is called or when an interrupt is acknowledged.
2.3.1
bit ( µ PD17241)/13-bit ( µ PD17242, 17243)/14-bit ( µ PD17244, 17245, 17246) address stack registers, and three 6-
bit interrupt stack registers.
20
A stack is a register used to save a program return address and the contents of system registers (to be described
Figure 2-5 shows the stack configuration.
A stack consists of a stack pointer (a 4-bit binary counter, the highest bit fixed to 0), five 11-bit ( µ PD17240)/12-
b
0
3
Stack
The RESET pin is
internally pulled down
and reset is effected.
Stack pointer
Stack configuration
SPb
b
2
(SP)
2
SPb
b
1
1
SPb
b
0
0
0H
1H
2H
3H
4H
5H
6H
7H
µ PD17240, 17241, 17242, 17243, 17244, 17245, 17246
0H
1H
2H
BANKSK0
b
BANKSK1
BANKSK2
Figure 2-5. Stack Configuration
13
b
b
5
12
Data Sheet U15002EJ1V1DS
b
11
BCDSK0
BCDSK1
BCDSK2
b
b
10
4
b
9
Address stack register 0
Address stack register 1
Address stack register 2
Address stack register 3
Address stack register 4
Address stack registers
Interrupt stack registers
µ
CMPSK0
CMPSK1
CMPSK2
PD17244, 17245, 17246
b
8
b
3
Undefined
Undefined
Undefined
µ
(INTSK)
b
PD17242, 17243
(ASR)
7
µ
b
PD17241
6
CYSK0
CYSK1
CYSK2
µ
PD17240
b
2
b
5
b
4
ZSK0
ZSK1
ZSK2
b
b
3
1
b
2
IXESK0
IXESK1
IXESK2
b
1
b
0
b
0