UPD17073 NEC, UPD17073 Datasheet - Page 23

• Manufacturer Part Number: UPD17073
• Description: 4-BIT SINGLE-CHIP MICROCONTROLLER WITH HARDWARE FOR DIGITAL TUNING SYSTEM
• Manufacturer: NEC

3.
3.1 General
interrupt has been accepted.
3.2 Address Stack Register (ASR)
assigned to ASR2, and the address stack register therefore consists of two 12-bit registers (ASR0 and ASR1).
has been accepted, and when a table reference instruction is executed.
Figure 3-1 outlines the address stack.
The address stack consists of a stack pointer and an address stack register.
The address of the address stack register is specified by the stack pointer.
The address stack saves return addresses when a subroutine call instruction has been executed and when an
The address stack is also used when a table reference instruction is executed.
Figure 3-2 shows the configuration of the address stack register.
The address stack register consists of three 12-bit registers ASR0-ASR2. Actually, however, no register is
The address stack saves return addresses when a subroutine call instruction has been executed, when an interrupt
b
0
3
ADDRESS STACK (ASK)
Stack pointer
b
0
(SP)
2
Bit
SP1 SP0
b
1
b
0
Stack pointer
Figure 3-2. Configuration of Address Stack Register
Specifies address
Address
0H
1H
2H
Figure 3-1. Outline of Address Stack
b
11
b
10
Address stack register (ASR)
b
9
b
8
ASR2 (Undefined)
b
7
ASR0
ASR1
Address stack register
Bit
b
6
Return address
b
5
b
4
b
3
b
PD17072,17073
2
b
1
b
0
Cannot
be used
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