APPENDIX K
end
__
os
1274-1275 ($4FA-$4FD)
P o ints to th e first b y te p as t th e lo w R A M are a u se d b y T O S . T his is u sed
fo r th e startin g a d d re s s o f th e T P A (en d
__
o s is co p ie d i n to
__
m em b ot).
exec
__
os
1278-1281 ($4FE-$501)
T his p o in ts to th e o p eratin g sy stem co m m an d sh ell w h ich is ex ecu te d
w h en sy ste m initializa tion is co m p lete. N o rm a lly , th is p o in ts to th e first
b y te of th e A E S te xt se g m e n t.
scr
_
dump
1282-1285 ($502-$505)
T h e S c rd u m p () ro u tin e is v ec to re d th ro u g h th is lo cation , so th a t w h en
S c rd u m p () is called , o r th e A ltern ate -H e lp k ey s are p res se d , p ro g ra m e x e
cu tio n is d irec ted to th e ro u tin e w h o se a d d re ss is fo u n d h ere . T o in stall a
p rin te r d riv er fo r a n o th e r p rin te r, th ere fo re, all y o u h av e to do is to lo ad
th e n ew scre e n prin t p ro g ra m as a term in a te-a n d -stay -re sid en t p ro g ra m
(se e P te r m r e s (), C h ap te r 5 ), a n d sto re its a d d re ss h ere.
T h is v ec to r ca n also b e d iv erte d fo r o th er p u rp os es. S o m e " s n a p s h o t"
p ro g ra m s , for exa m p le , u se th is v e cto r to in stall a ro u tin e th at sa v es th e
scree n p ictu re to a a is k file w h e n th e A lte m a te -H e lp k e ys ar e p re sse d ,
ra th er th an se n d in g it to a p rin ter. It's a lso po ssib le to in stall a sh o rt ro u
tine th at te sts for snift ke ys w h e n A lte m ate -H e lp is p re ss ed , th u s allo w in g
ad d itio nal h o t-k ey p ro g ra m s to be in sta lled , rath e r th an ju st re p lacin g th e
scree n p rin t fu nctio n.
prv__Isto
1286-1289 ($506-$509)
T h is v ec to r is u sed b y P r tb l k () to call th e P R N : d ev ice o u tp u t sta tu s ro u
tine.
prv
__
1st
1290-1293 ($50A-$50D)
T h is v e cto r is u sed b y P rtb lk () to call th e P R N : d ev ice o u tp u t ro u tin e.
prv__auxo
1294-1297 ($50E-$511)
T his ve cto r is u se d b y P rtb lk () to call th e A U X : d ev ice o u tp u t sta tu s ro u
tine.
prv
__
aux
1298-1301 ($512-$515)
T his v e cto r is u sed by P r tb lk () to call th e A U X : d ev ice o u tp u t ro u tin e.
402
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