19 Jan
2007
19 Jan
'07
12:55 a.m.
> Not unless you lift yourself by your bootstraps
to do it. It is
> obviously a physical impossibility, just like using the operating
> system functions that are available once the OS is loaded, for loading
> the operating system.
On Wed, 17 Jan 2007, Chris M wrote:
Oi. The code that's embedded in the system rom,
which
is usually invoked by an "INT" is there whether the OS
is loaded or not, no?
Not necessarily. The BIOS INTs are mostly in ROM. The OS INTs are loaded
in a later stage of the bootstrapping.
My point was all the facilities
for formatting tracks, and reading and writing
individual sectors is present there.
In general, yes. You might run into a few complications with setting
configurations.
A very simple
program is required to copy the contents of a disk in
a: to a disk in b:. I remember doing this as an
exercise when I learned assembly language. Under 20
lines iirc, and I did it w/debug. Therefore what would
be the problem of having the post, instead of handing
off control to bootstrap code, execute a snippet of
code which formats a disk, then copies the contents of
another disk to it. Of course this would require a
V9000 to have the ability to natively read a vanilla
IBM format.
Are you sure that it can read PC style MFM without loading significant
additional software?
And of course you'd need to add the code
to a custom eprom. In theory it should work.
IF it can read PC style MFM, then I would recommend rewriting the boot
code to boot from an MFM diskette.
Most bootstrapping these days seems to consist of ROM code sufficient to
display on the screen (THAT makes life easier!), and sufficient disk I/O
in ROM to copy the first sector of a disk into a fixed RAM location and do
a jump to that location. IF that code can handle MFM, then I'd recommend
making a modified version of it that expects MFM. Then you can write any
programs that you need in the first sector of a floppy disk, and expect it
to be loaded into memory and jumped to. As you've mentioned, you can
accomplish a LOT in 512 bytes. If THAT isn't enough, then you can include
code in the first sector to load x additional sectors. Once you've
written a bootstrap routine, the rest just follows from there, although be
aware that porting Windoze to the Victor 9000 would be a helluva lot of
work, and not well received by some. :-)
Writing a DEBUG ROM would be especially useful.
--
Grumpy Ol' Fred cisin at xenosoft.com