Atari ST series - Page 403

ST Memory Map
on d . T his is th e v alu e th at is re tu rn ed b y th e BIO S fu n ctio n T ic k ca l(). T his
v alu e is also p la ced o n th e sta ck b efore th e tim er in terru p t h an d le r calls
th e tim e r h an d o ff v e cto r.
__ fverify
1092-1093 ($444-$445)
F lo p p y d isk w rite v erify flag. W h e n th e va lu e sto re d h er e is n o n ze ro (th e
d efau lt), all w rites are v erified . W h e n ze ro , w rite v erify is tu rn ed off.
__ bootdev
1094-1095 ($446-$447)
T his lo cation c on ta in s th e n u m b e r o f th e d ev ice from w h ich th e sy ste m
w a s b o ote d .
almode
1096-1097 ($448-$449)
A 0 in dic a tes th a t N T SC (6 0 H z , U .S .) v id eo o u tp u t is u se d . A n o n ze ro
v alu e in d ica tes th a t th e vid e o o u tp u t is P A L (5 0 H z , E u ro p ea n ).
defshftmd
1098-1099 ($44A-$44B)
T h e d efa u lt vid eo reso lu tio n . If th e sy ste m is shifte d from m o n o ch ro m e to
co lo r, th e va lu e h er e d eterm in es w h e th e r th e co lo r s cr ee n is b ro u gh t u p in
low re so lu tio n (0 ), o r m e d iu m re so lu tio n (1).
sshiftmd
1100-1101 ($44C-$44D)
C o n tain s a s h ad o w c o p y o f th e sh iftm d h ard w a re reg ister, w h ich d eter 
m in es th e scre e n d isp lay m o d e:
V alu e S cre en D is p la y M o d e
0 3 20 x 2 00 , 16 co lo rs (low reso lu tio n )
1 6 4 0 x 2 00 , 4 co lo rs (m e d iu m re so lu tio n )
2 6 4 0 x 4 0 0, 2 co lo rs (h ig h re so lu tio n )
__ v __ bas__ad
1102-1105 ($44E-$451)
T his loca tio n co n ta in s th e sta rtin g ad d re s s o f scre e n R A M , a 32 K m e m o ry
are a th a t a lw ay s sta rts o n a 51 2-b y te b o u n d a ry .
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