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80286
SYSTEM .INITIALIZATION
Define
the
templ.te
for.
temporary
GDT
u.ed
to
locate
the
Initial
GDT
and
.tock.
Thl.
data
will
be
copied
to
location
O.
Thl5
.pace
Is
01.0
u.ed
for
a
temporary
stack
and
finally
.erve'
a.
the
T55
wrillen
inlo
when
entering
Ihe
Initial
T55.
org
Place
remaining
code
below
power
_u
p
Inltlal_gdt
de.c
< )
Fill
e r
and
nul
I
IDT
de.crlptor
gdt_de.c
de.c
< )
De.crlptor
for
EPROM
GDT
Idl_de!C
de.
c
< )
De.crlptor
for
EPROM
IDT
lemp_de.c
de.c
< )
Temporary
de.crlptor
Define
a
de5Crlptor
Ihat
will
point
the
GDT
at
location·
D.
Thl.
de.crlplor
will
al.o
be
loaded
Inlo
5510
define
Ihe
Initial
prolected
m~de
slack
.egmenl.
desc
< e n
d_g
d I - I n I I I a
I_g
d t - 1 , 0 , 0 , D
S_A
C C E 5 S , 0 )
Define
the
TS5
descriptor
u.ed
to
allow
the
t
••
k
.wltch
to
the
flr.t
task
to
overwrite
thl.
region
of
memory.
The TS5
will
overlay
the
Initial
GDT
and
.tack
at
·Iocatlon
D.
desc
Define
the
Initial
.tack
space
and
filler
fo~
the
end
of
the
TSS.
.tart_polnter
dw
I
abe
I
lobe
I
dw
8
dup
(0)
word
dword
o , •
tar
t_
t
ask
;
Pointer
to
Inilial
la.k
Define
lemplate
for
the
la.k
definition
11.1.
ta.k_entry
T55_.el
T55_alla.
LDT_alla.
ta.k_entry
re.et_.tartup:
c
II
c I d
lor
• I r u c
dw
dw
dw
end.
ta.k_entry
d w 0
d I , d I
mov
d.,dl
mov
!!!I,dl
• • , d I
Define
layout
of
ta.k
de.crlptlon
Selector
for
TSS
Data
.egment
all
••
for
TSS
Dolo
.egment
alia.
for
LDT
If
any
<~tarl_task,.tart_TSS_alla.,.lar~_LDT_alla.)
;
Terminate
II.t
No
Interrupt.
allowed!
U.e
autolncrement
mode
Point
ES:DI
at
phy.lcal
addre
••
DDDOODH
Set
.tack
at
end
of
re.erved
area
mov
mov
• P ,
en
d_g
d t - I
nit
I a
I_g
d t
A-3