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| From: Martijn van Buul
Date: 1998-05-17
Subject: Re: Tapes!
|
Mike Dailly wrote:
> Yep... I just double checked and the first 4 bytes of the header are
> the start address, and the end address. The plus/4 always loads
> whereever the tape wants... allowing auto runs with ease... I've even
> seen loaders loading more code, but using the left over space in the
> header as well!
Hmm.. Hmm.. I tried to crack one of my tape games this morning (this thread made me interested ;) but I'm having a hard time with this one.
According to the tapeheader, the loader loads from $020F (which is the BASIC/ASSEMBLY working area). However, I just don't seem to be able to load that darn thing at another location (like $120F). Tedmon doesn't support it, and even the normal SETLFS / SETNAM / LOAD sequence (with a secondary adress of 0) doesn't work (*) with this one. It just keeps on booting.. Guess I'll have to disassemble the ROM, since the LOAD routine isn't finished normally. (Heck! It seems that the copy protection is more sophisticated than the game... Moon Buggy isn't that thrilling again..)
(*) I still have to check it, but is it true that the SETLFS routine of a
plus/4 or 16 is somewhat different than the one in a C64? According
to a rom-disassembly, A should contain the locigal file number,
X should contain the device number and Y should contain the secondary
adress. My C64 reference guide however seems to want it in another way:
A devicenumber, X logical file number, Y secondary address.
I guess I'll have to dissassemble the C64 SETLFS in order to be sure,
but that involves a serious rearangement of my desk :)
--
Martijn van Buul, martijnb@mud.stack.nl Tijntje@OuterSpace - 131.155.141.166 3333
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