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8086 Flag Register Architecture

General Introduction

Introduction
in 8086 Computer system we use flag register, its purpose is to show status of other registers and the CPU in general, in some cases the status can be used as indication for programming the system.
Flag Register

Registger Flags
bit flag name and symbol discription
0 Carry Flag - CF show carry when value not fit in register size
1 Not used X
2 Parity Flag - PF show if value off\even after arithemric\logic operation
3 Not used X
4 Auxiliary Carry - AC Carry ot support BCD arithmetic
5 Not used X
6 Zero Flag - ZF show if register is Zero after arithmetic\logic operation
7 Sign Flag - SF
8 Trap Flag - SF


Flag Register Connected to ALU

the flags are connected to ALU