[Coco] CocoSDC booting OS9

Brett Gordon beretta42 at gmail.com
Tue Nov 18 07:43:20 EST 2014


As of now, HDBDOS only support the standard FDC emulation of SDC.  The LBA
mode of SDC isn't support by HDBDOS, until someone writes a driver for it.
I might take up that project of the toolshed people see fit, as it will
benefit the community plus help my cocoboot project (which borrows the
HDBDOS drivers for its harddrive/DW)

Usually, I think most user partition there HD's with OS9 at the beginning,
and HDBDOS *after* it.  With Boisey's Super Driver for OS9 you can
partition the drive the other way around with HDBDOS drives taking the
lower partition and OS9 the higher. If you format your HD this way, then
you have the ability to create a bootdisk that is readable from HDBDOS (and
the DOS command) solve the Bob's proposed dillema.

To answer Bob's original question:

At clusters of 1 sector (the defacto standard?), a Combined OS9 RBF with a
boottrack can be:

630 sectors - 18 boottrack - 1 superblock = 611 sector for allocation bitmap
X 256 bytes per sector = 156,416  bytes for allocation bitmap
X 8 bits per byte = 1,251,328 bits in allocation bitmap
X 256 bytes per sector = 320 Megs

-Brett

On Nov 17, 2014 10:20 PM, "Robert Gault" <robert.gault at att.net> wrote:

> Brett Gordon wrote:
>
>> That sounds like a fine idea!  It's just a matter of changing OS9 and
>> BASIC to agree to do something different.
>>
>>
> I don't have the SDC and don't know how it is supposed to work. If it
> supports HDBDOS and can accept a .vhd such as is used by a real Coco, the
> JCV, MESS, and VCC emulators, then it is trivial to place a 35-track single
> sided "disk" in the Disk Basic portion of the .vhd. That is your OS-9 boot
> disk and there is no need to worry that OS-9 and Basic use different
> directory structures.
>
> You can also set up the boot disk for automatic booting at turn on, if you
> only use OS-9.
>
> Robert
>
>
>
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