APPENDIX K
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membot
1 0 7 4 - 1 0 7 7 ( $ 4 3 2 - $ 4 3 5 )
A p o in ter to th e lo w e st availab le m em o ry location . T h e BIO S G e tm p b ()
fun ctio n u ses th is va lu e as th e star t o f th e G E M D O S T ran sie n t P ro g ra m
A re a (T P A ).
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memtop
1 0 7 8 - 1 0 8 1 ( $ 4 3 6 - $ 4 3 9 )
A p o in te r to th e h ig h est available m e m o ry lo ca tio n . T h e B IO S G e tm p b ()
fu n ction u se s th is va lu e as th e e n d o f th e G E M D O S T ran sie n t P ro g ra m
A re a (T PA ).
memval2
1 0 8 2 -1 0 8 5 ( $ 4 3 A - $ 4 3 D )
If th is lo ca tio n co n ta in s th e m ag ic n u m b er $2 3 76 98 A A , an d th e m a gic
n u m b er in m em v alid (1 0 56, $4 20 ) is also co rre ct, th en th e co ld sta rt w a s
su cce ssfu l, a n d th e m em o ry con fig u ratio n in m em cn tlr (b elow ) is co rre ct.
flock
1 0 8 6 - 1 0 8 7 ( $ 4 3 E - $ 4 3 F )
F lo p p y lo ck v ariab le . If it co n tain s a v alu e o th e r th an ze ro , th e vertical
blan k d isk ro u tin e is d isab led , w h ich g u ara n te e s th at it d o e sn 't to u ch th e
D M A chip re gisters. T his variab le m u st b e n o n z ero w h en th e D M A b u s is
b ein g u sed .
seekrate
1 0 8 8 - 1 0 8 9 ($ 4 4 0 - $ 4 4 1 )
Bits 0 a n d 1 o f this w o rd co n ta in th e d e fa ult se ek ra te (th e tim e it ta k e s for
th e h ea d to m ov e to th e n e xt tra ck ) fo r b oth flo p py d riv es:
Value in
Bits 0 and 1 Seek Rate (in Milliseconds)
0 6
1 12
2 2
3 3 (d e fau lt)
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timr
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ms
1 0 9 0 -1 0 9 1 ($ 4 4 2 - $ 4 4 3 )
T h e tim e b etw e en sy stem tim er ticks in m illise co n d s . F o r cu rre n t S Ts, th is
v alu e is 2 0 m illiseco n ds, w h ich co rre s p o n d s to 50 tim er u p d ate s p er se c
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