CPU Registers are small amounts of memory located on the processor. They provide a fast way to process data.
x86 registers
General purpose registers
| 32 bit
|
16 bit
|
8 high bit
|
8 low bit
|
description
|
| eax
|
ax
|
ah
|
al
|
accumulator
|
| ebx
|
bx
|
bh
|
bl
|
base
|
| ecx
|
cx
|
ch
|
cl
|
counter
|
| edx
|
dx
|
dh
|
dl
|
data
|
Segment registers
| 16 bit
|
description
|
| cs
|
code segment
|
| ds
|
data segment
|
| es, fs, gs
|
extra segment
|
| ss
|
stack segment
|
Index registers
| 32 bit
|
16 bit
|
description
|
| esi
|
si
|
source index
|
| edi
|
di
|
destination index
|
Pointer registers
| 32 bit
|
16 bit
|
description
|
| ebp
|
bp
|
base pointer
|
| esp
|
sp
|
stack pointer
|
| eip
|
ip
|
index pointer
|
EFLAGS register
| bit
|
label
|
description
|
| 0
|
cf
|
carry flag
|
| 2
|
pf
|
parity flag
|
| 4
|
af
|
auxiliary flag
|
| 6
|
zf
|
zero flag
|
| 7
|
sf
|
sign flag
|
| 8
|
tf
|
trap flag
|
| 9
|
if
|
interrupt flag
|
| 10
|
df
|
direction flag
|
| 11
|
of
|
overflow flag
|
| 12-13
|
iopl
|
i/o priviledge level
|
| 14
|
nt
|
nested task flag
|
| 16
|
rf
|
resume flag
|
| 17
|
vm
|
virtual 8086 mode flag
|
| 18
|
ac
|
alignment check flag
|
| 19
|
vif
|
virtual interrupt flag
|
| 20
|
vip
|
virtual interrupt pending
|
| 21
|
id
|
id flag
|
Control registers
Debug registers
| dr0
|
dr1
|
dr2
|
dr3
|
dr4
|
dr5
|
dr6
|
dr7
|
Test registers
Pmode segmentation registers
| gdtr
|
global descriptor table register
|
| idtr
|
interrupt descriptor table register
|
| ldtr
|
local descriptor table register
|
| tr
|
task register
|
