From: Ullrich von Bassewitz (uz_at_musoftware.de)
Date: 2002-11-19 23:55:21
On Tue, Nov 19, 2002 at 06:57:06PM +0100, Marc 'BlackJack' Rintsch wrote:
> > * Because of limitations of the CBM floppies, you can open a file
> > either for reading or for writing, but not for both. Similar, append
> > mode is not available.
>
> The 1541 can open files for appending data, what about other CBM drives?
The information I had was this: Append mode (the 'a' flag) is available only
for sequential files. So I left it out, because I thought this was too
limiting. However, Stefan Haubenthal bugged me because of the append mode, so
I looked a bit more into it and found that user ('U') and program ('P') files
are actually sequential files, so append mode should work, even if this is not
explicitly specified in the manual (BTW: the Commodore manuals are pretty bad
in most respects).
As a result, append mode is already implemented and seems to work fine. I
didn't try other drives than the 1541, but at least the manual for the 1571
states that append mode is possible. I expect it to work with all drives newer
than the 1541.
BTW, there's a bug in VICE, at least in version 1.9: When not using true drive
emulation, append mode will not work. Since it works in true drive emulation,
I assume that this is a VICE problem.
I've also tested other platforms: The file routines work without problems on
the C64, C128 and Plus/4. The current linker config for the VIC20 was too
limited for my test program (3.5K), but I do not expect problems on the VC20
either. The biggest problem seems to be the PET because many functions
available in the kernal jump table for later machines do not exist on this
platform. I'm working on it...
Regards
Uz
--
Ullrich von Bassewitz uz_at_musoftware.de
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