User's Manual

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