Commodore 64 Handbook page 40

Then type NEW, and us e the -following c h e c k s u m p r o g r a m to e n a b l e you to
i d e ntify and loc a te any errors:
100 REM E X T R A M 0 N 6 4 C H E C K S U M P R O G R A M
110 DAT A 1 0 1 7 0 , 1 3 6 7 6 , 1 5 4 0 4 , 1 4 9 9 7 , 1 5 1 3 6 , 1 6 2 2 1 , 1 6 6 9 6
115 D A T A 1 2 8 1 6 , 1 6 2 2 8 , 1 4 5 5 4
120 DAT A 1 4 6 7 7 , 1 5 0 3 9 , 1 4 5 5 1 , 1 5 1 0 4 , 1 5 5 2 2 , 1 6 4 1 4 , 1 5 9 1 4
125 D A T A 8 9 5 8 , 1 1 9 4 5 : S = 2 0 4 8
130 F 0 R B = 1 T O 19:R E A D X :FORI = 1T O S : N = P E E K <I ):V = Y + N
140 NEX T I: IFY< > X T H E N ? " E R R O R IN B L O C K "B : G 0 T 0 1 6 0
150 P R I N T " B L O C K "B" C OR R E C T "
160 S = I :Y = 0 : N E X T B :R E M C H E C K L A S T B L OC K BY H A N D
This p r o g r a m mu st be run a f ter the fi rst set of POKEs, and b e f o r e the
seco n d set.
If e r r o r s ar e found, ty p e N E W (you won't lose E x t r a m o n ! ), r e - l o a d Tiny
P e e k e r / P o k e r , en te r blo c k of m e m o r y again, t y p e NEW, r e - l o a d c h e c k s u m
program, run it, if e r r o r s fou nd t yp e N E W and r e - l o a d Tiny
P e e k e r / P o k e r , and so on until no e r r o r s remain. Then, iss ue last set
of P O K E s and S A V E Extramon!
E x t r a m o n I n s t r u c t i o n Set
This will be g i v en in the f o r m CO M MA N D, f o l l o w e d bv th e syntax.
1) S i m p l e As s e m b l e r
.A 2000 L D A £ 1 2
start a s s e m b l y at 2 0 0 0 hex.
2) D i s a s s e m b l e r
.D 2 0 0 0
d i s a s s e m b l e hex fro m 2 0 0 0 onwards.
3) P r i n t i n g D i s a s s e m b l e r
.P 2 0 0 0 , 2 0 4 0
e n g a g e p r i nte r b e f o r e h a n d wi t h 0 P E N 4 ,4:CMD4.
4) Fill memor v
•F 1000 1100 FF
fill m e m o r y f r o m 1000 to 1100 hex wit h the b y t e F F .
5) Go run
.G 1 0 0 0
go to hex 1000 and e x e c u t r e p r o g r a m there.
6) Hunt m e m o r y
.H C 0 0 0 D 000 R E A D
look from C 0 0 0 to D0 0 0 for th e A SCII s tr in g READ.
7) Load
.L " F R E D " ,08
8) M e m o r y d i s p l a y
.M 0 8 0 0 0 8 2 0
d i s p l a y m e m o r y f r o m hex 0 8 0 0 to 0820.
9) R e g i s t e r d i s p l a y
.R
d i s p l a y s r e g i s t e r va l u e s w hen E x t r a m o n was entered.
10) S a v e
.S "0:F R E D " , 0 8 , 0 8 0 0 , 0 8 2 0
s a v e m e m o r y f r o m hex 0 8 0 0 to 0 8 2 0 o n t o d e v i c e 0 8 d r i v e 1, and call
that p o r t i o n of m e m o r y FRED.
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