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o n d . T h is is t h e v a l u e t h a t is r e t u r n e d b y t h e B I O S f u n c t i o n T i c k c a l ( ) . T h is
v a l u e is a l s o p l a c e d o n t h e s t a c k b e f o r e t h e t i m e r i n t e r r u p t h a n d l e r c a lls
t h e t i m e r h a n d o f f v e c t o r .
1092-1093
F l o p p y d i s k w r i t e v e r i f y f la g . W h e n t h e v a l u e s t o r e d h e r e is n o n z e r o ( t h e
d e f a u l t ) , a ll w r i t e s a r e v e r if ie d . W h e n z e r o , w r i t e v e r i f y is t u r n e d o f f.
1094-1095
T h is l o c a t i o n c o n t a i n s t h e n u m b e r o f t h e d e v i c e f r o m w h i c h t h e s y s t e m
w a s b o o t e d .
1096-1097
A 0 i n d i c a t e s t h a t N T S C ( 6 0 H z , U . S . ) v i d e o o u t p u t is u s e d . A n o n z e r o
v a l u e i n d i c a t e s t h a t t h e v i d e o o u t p u t is P A L ( 5 0 H z , E u r o p e a n ) .
1098-1099
T h e d e f a u l t v i d e o r e s o l u t i o n . If t h e s y s t e m is s h i f t e d f r o m m o n o c h r o m e to
c o l o r , t h e v a l u e h e r e d e t e r m i n e s w h e t h e r t h e c o l o r s c r e e n is b r o u g h t u p in
lo w r e s o l u t i o n ( 0 ) , o r m e d i u m r e s o l u t i o n ( 1 ) .
1100-1101
C o n t a i n s a s h a d o w c o p y o f t h e s h i f t m d h a r d w a r e r e g i s t e r , w h i c h d e t e r
m i n e s t h e s c r e e n d i s p l a y m o d e :
V a l u e
S c r e e n D i s p l a y M o d e
0
3 2 0 x 2 0 0 , 1 6 c o l o r s (l o w r e s o l u t i o n )
1
6 4 0 x 2 0 0 , 4 c o l o r s ( m e d i u m r e s o l u t i o n )
2
6 4 0 x 4 0 0 , 2 c o l o r s ( h i g h r e s o l u t i o n )
1102-1105
T h is l o c a t i o n c o n t a i n s t h e s t a r t i n g a d d r e s s o f s c r e e n R A M , a 3 2 K m e m o r y
a r e a t h a t a l w a y s s t a r t s o n a 5 1 2 - b y t e b o u n d a r y .
ST Memory Map
__fverify
__bootdev
almode
defshftmd
sshiftmd
__v__bas__ad
($444-$445)
($446-$447)
($448-$449)
($44A-$44B)
($44C-$44D)
($44E-$451)
395
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