bytes to replace the two zeros, follow this procedure. We know
the first four bytes are pointer bytes ($0801-$0804). We also
know that the next time a zero byte appears in memory ($080D),
it signals a new line. The next address is the address that the
pointer will point to ($080E). Therefore, the first two bytes in
this program should be 0E 08 because all addresses are read in
reverse order. Now we can scroll to the two zeros at $0801 and
type over them 0E 08 and hit RETURN. The first four bytes
starting at $0801 should now be 0E 08 0A 00 (the 0A 00 bytes
represent the line number in reverse 0A 00=00 0A=10 in
decimal). Our Basic program is now repaired and all that is left
is to locate the end of the program and save it to our backup
disk. To find the program end, use the HUNT command in your
monitor. We'll hunt for the first three EA bytes that signal the
end of the program that we loaded in <> H 0801 2000 EA EA EA <>.
This search will bring back the address $08A5. Disassembly of
code around this address reveals a small machine language
program placed under a Basic program. To properly capture all
the necessary code, we must save the code from the beginning of
Basic ($0801) to the beginning of our EA bytes ($08A5). Because
all monitors require us to add one extra byte to the end
address, use this command: <> S"BOOT",08,0801,08A6 <>.
When the save is complete, you will have a broken copy that will
no longer do a protection check. We have essentially replaced the
auto boot and the protection check with the result, a small program
consisting of a Basic loader with a machine language routine placed
under it.
CREATIVE CONTRAPTIONS : BANTAM
Procedure:
Loading the original produces a rattle free load, and an error
scan shows no standard errors. A backup made with the C-64 Fast
Copier produces a non-working copy. A backup made with a nybbler
produces the same non-working copy. Before starting to work on this
program, please make a non-working backup of the original.
Working with your backup:
l) Start by scratching the first file from your backup
<> OPEN15,8,15, "S0:CREATIVE":CLOSE15 <>.
Working with your original:
2) Place a write protect on the original to ensure its safety
during the breaking process.
K.J. REVEALED TRILOGY PAGE [19] (C)1990 K.J.P.B.
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