to be short: I don't think it is possible to boot from a CDROM in DOS2.
DOS2 uses the DISKIO entry for reading the bootsector, and since this
entry only supports 512kB sectors, I think you can forget it :(
About only accessing the partitions (not booting): best thing to do is
just make a normal ISO9660 cd and use the CDEX utility to access files
on the cdrom.
Jon
Maarten ter Huurne wrote:
>
> On Saturday 04 November 2000 19:13, you wrote:
>
> > Hmm. I don't have linux (yet) but I can ask someone with Linux. Or does
> > someone know if there's no W98 or DOS program able to fix this.
>
> The source of wrdsk is part of the fMSX source distribution. It seems wrdsk
> uses the parameters from the boot block (boot sector contents) to calculate
> the disk size. So feeding it a harddisk boot sector should be sufficient to
> allow up to 32MB of data.
>
> There is another problem though, which is that wrdsk doesn't support
> subdirectories.
>
> > Hmm.. let's see if i got you correct:
> > So you suggest that I should make a file which contains concatenated binary
> > copies of the files I want to put on my disc .
> > Then I should create in a hex-editor a BERT-partition table _however it
> > might look like_. It's almost for sure that the beginning and the end (or
> > the length) must be specified in the table. Then i should figure out these
> > values so that they are at the start of new files. This binary file then
> > should be concatenated to the file containing the software I want on CD.
> >
> > Did I understand you correct?
>
> I'm not sure. I'll explain more formally, so there is less chance of
> misunderstandings.
>
> CD = boot_block + partition[0] + partition[1] + ... + partition[N-1]
>
> boot_block contains the partition table, boot sector and probably some empty
> space.
>
> partition[i] is a partition image, which is like a disk image only bigger.
>
> The "+" operation is binary file concatenation.
>
> Usually a partition table contains the number of the first absolute sector of
> a partition and the number of the last (inclusive) absolute sector of a
> partition. Also, there is data like "partition type" (primary FAT, secundary
> partition etc) and "bootable flag" (bootable yes/no).
>
> You have to make a partition table (either using hex editor or by writing a
> program) that points to the absolute sector addresses at which the partition
> images are located. If you mean partition images by "at the start of new
> files", you understood correctly.
>
> > > There may be another problem: it's not sure the BERT interface (or rather
> > > its disk ROM) will allow you to use partitions from CD-ROM. CD-ROM sectors
> > > are 2048 bytes in size, while harddisk sectors are 512 bytes.
> >
> > You've got a point there, I didn't knew about that. To access a CD-ROM i
> > need the programs ccd.com (to enter a directory), ccopy.com (to copy files
> > from CD-ROM to eg Harddisk) and cdda.com (to start/stop/.../pause an
> > audio-CD)
> > I always thought that they were only necessary to deal with the
> > FAT12-problem.
>
> They are needed anyway to understand the iso9660 filesystem, which is used on
> CD-ROMs. But I don't know whether sector length is also an issue.
>
> > Or does the fact that the BERT supports a CD-ROM drive tell enough about
> > dealing with the different sector size?
>
> That depends on whether ccd.com and ccopy.com use the same routines to read
> sectors as DOS2 does. Also, DOS2 itself must be able to handle larger
> sectors, if it loads 2048 byte sectors into 512 byte buffers, it will most
> likely crash.
>
> Does anyone know the size of ZIP disk sectors? Those work under DOS2.
>
> > Siebe -today subscribed to this mailinglist- Berveling
>
> Welcome!
>
> Bye,
> Maarten
>
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