R1610C RDC Semiconductor, R1610C Datasheet - Page 22

• Manufacturer Part Number: R1610C
• Description: High Performance 16 Bits MCU Integrated One 10/100M Mac Controller - 3.3V Operating Voltage/2.5V Core Voltage
• Manufacturer: RDC Semiconductor

R
These flags reflect the status after the Execution Unit is executed.
R
6.3 Instruction Pointer and Status Flags Registers
DS (Data Segment): The DS register points to the current data segment, which generally contains program
variables. The DS register is initialized to 0000H.
SS (Stack Segment): The SS register points to the current stack segment, which is for all stack operations, such
as pushes and pops. The stack segment is used for temporary space. The SS register is initialized to 0000H.
ES (Extra Segment): The ES register points to the current extra segment, which is typically for data storage, such
as large string operations and large data structures. The ES register is initialized to 0000H.
fetched. The IP register cannot be directly accessed by software, but can be updated by the bus interface unit. It
can be changed, saved or restored as a result of program execution. The IP register is initialized to 0000H and
the starting execution address for CS:IP is at 0FFFF0H.
15-12
22
Register Name:
Reset Value
15
Bit
10
11
9
D
D
IP (Instruction Pointer): The IP is a 16-bit register and it contains the offset of the next instruction to be
14
Reserved
Name
Rsvd
C
C
OF
DF
IF
13
®
®
:
Reserved.
Overflow Flag. If an arithmetic overflow occurs, this flag will be set.
Direction Flag. If this flag is set, the string instructions are in the process of incrementing
address. If DF is cleared, the string instructions are in the process of decrementing address.
Refer to the STD and CLD instructions for how to set and clear the DF flag.
Interrupt-Enable Flag. Refer to the STI and CLI instructions for how to set and clear the IF flag.
Set to 1: The CPU enables the maskable interrupt request.
Set to 0: The CPU disables the maskable interrupt request.
R
R
I
I
S
S
C
C
Processor Status Flags Register
0000h
D
D
12
S
S
P
P
C
C
o
o
m
m
m
m
u
u
OF
11
n
n
i
i
c
c
a
a
15
t
t
i
i
o
o
SEGMENT REGISTERS
n
n
DF
10
IF
9
8
CS
DS
ES
SS
7
TF
8
SF
7
Description
0
ZF
6
Stack Segment
Extra Segment
Code Segment
Data Segment
Rsvd
5
AF
4
Fast Ethernet RISC Processor
Rsvd
3
PF
2
Rsvd
1
R1610C
October 27, 2003
CF
0
Final Version 1.5
Data Sheet