ruud.baltissen_at_abp.nl
Date: 2008-01-07 11:06:19
Hallo Jim,
> Can;t you just mark the parent dir entry with a length of 1 when
> you are creating the dir?
I want to use as much standard routines as possible:
1) to save space
2) to remain compatible
3) to make it as understandable as possible for outsiders
This means that I want to update the entry when I have created the
subdirectory, just like the directory is updated AFTER the file is saved
and the number of blocks is known. Problem: I haven't found the place
where this number is updated yet. The file is closed at CloseFile [DB02]
(*). Here is a routine called that, IMHO, writes the last sector:
WriteLastSec [DB62]. Immediatly after this routine the directory is
written and the BAM is updated. But I haven't yet found the update of
the size of the file itself. If possible I want to use the same
routines. But not understanding them (yet), makes it difficult to use
them. That's why I asked for samples of sources doing these kind of
tricks.
But I already found out that these are rare. Books like "Inside
Commodore DOS" give you all kind of info about dealing with the 1541 on
a very low level like calling jobs, or high level things like OPEN 1, x,
y, "..... but not mid-level things like creating your own routines
inside the 1541.
And it is more difficult then I thought. I thought I could use the SAVE
routine as example so I started to follow the thread starting at
OPEN_N15. It ends at $D8D6 where a JMP to OpenFile4Write takes place. So
edited some variables like TYPE and MODE and called the routine. A
sector is indeed allocated but no entry is made. Doing some research I
found out that an entry is made but in a wrong way. Then I just copied
the beginning of the COPY [C8F0] routine and started to scratch lines.
So I found out that I only needed one routine to get things going:
Srch_file_dir [C44F]. Studying this routine didn't clear anything; I
have no idea what special thing this routine does so my own routine
suddenly works :(
But I cannot use this try-and-error method all the time because 1) it
eats up valuable time and 2) I end up with a routine that I don't
understand myself. Worse, if things go wrong, where should I look for
???
If nobody has any sample sources, it just means that the development
takes longer then I hoped. Do not misunderstand me, this is not a
complaint! Having had a deep dive into the sources I now understand it
is quite difficult material to handle, something that is not easy to
change.
(*) All the sources I have produced until now are based on my original
1541.ASM. So the above routines can be found at least by their name. A
reference like [C44F] means that this routine is found at address $C44F
in a 1541. This isn't true anymore for the newer sources but help you to
find the original routine in another 1541 source then mine.
> It'll never be anything else, no?
Like a normal directory, it should be expandable. Hmmm, what about
directories that once contained hundreds of files and now are empty?
Another challenge I think :)
> I saw Ruud has a design, but I really wanted to just buy something.
> Ruud, you want to build me one?
To be honest, no. I'm sorry but 1) it will take quite some time to build
it, time I want to spend on this IDE project and 2) it only works under
real MS-DOS. But if you still want it, you can have my proto-type.
Hallo Peter,
> Are you using one of those ROM/RAM boards, Ruud?
No.
1) I deliberately choosed a 1541-II because its ROM can be replaced by a
27128 and , after some soldering, by a 27256. For a 1541 you'll need two
28 pin adapters, or one plus a soldering hack.
2) I placed a 28-pins textool socket in the original socket so changing
ROMs is done in seconds.
3) I use an AT29C256 which can be programmed much faster then an EPROM.
And no erasing needed either.
> Perhaps support can be hacked into VICE easily...
THAT would be great! That would simplify development as I don't have to
program ROMs anymore. Who do I have to bribe? :)
--
___
/ __|__
/ / |_/ Groetjes, Ruud
\ \__|_\
\___| URL: Ruud.C64.org
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