Steve Nickolas

I've seen this title applied to something like what I've seen on a few
disks. They'll be 13-sector, and have a bootstrap that boots on either a
13 or 16-sector drive.

Anyone know how this could be pulled off, how one could create their own
"universal" disk?

-uso.

ict@ccess

On Jan 13, 10:07*pm, Steve Nickolas
<lyricalnan...@usotsuki.hoshinet.org> wrote:
> I've seen this title applied to something like what I've seen on a few
> disks. *They'll be 13-sector, and have a bootstrap that boots on eithera
> 13 or 16-sector drive.
>
> Anyone know how this could be pulled off, how one could create their own
> "universal" disk?
>
> -uso.

Probably both DOS's are on the same disk and you get a choice which
one you want to boot in to. Same idea as a dual boot DOS 3.3 / PRODOS
disk.

Rob

Vladimir Ivanov

On Sat, 14 Jan 2012, Steve Nickolas wrote:

> I've seen this title applied to something like what I've seen on a few disks.
> They'll be 13-sector, and have a bootstrap that boots on either a 13 or
> 16-sector drive.
>
> Anyone know how this could be pulled off, how one could create their own
> "universal" disk?

One sector #0 in 13-sector format and one sector #0 in 16-sector format,
both on track #0?

ict@ccess

On Jan 14, 12:51*am, "ict@ccess" <gids...@sasktel.net> wrote:
> On Jan 13, 10:07*pm, Steve Nickolas
>
> <lyricalnan...@usotsuki.hoshinet.org> wrote:
> > I've seen this title applied to something like what I've seen on a few
> > disks. *They'll be 13-sector, and have a bootstrap that boots on either a
> > 13 or 16-sector drive.
>
> > Anyone know how this could be pulled off, how one could create their own
> > "universal" disk?
>
> > -uso.
>
> Probably both DOS's are on the same disk and you get a choice which
> one you want to boot in to. *Same idea as a dual boot DOS 3.3 / PRODOS
> disk.
>
> Rob

Ha! Just realized DOS has even booted yet. That would take a few
coffees and late nights following that code. Tis will be known as the
ultimate crack.

Rob

Steve Nickolas

On Fri, 13 Jan 2012, ict@ccess wrote:

> On Jan 13, 10:07*pm, Steve Nickolas
> <lyricalnan...@usotsuki.hoshinet.org> wrote:
>> I've seen this title applied to something like what I've seen on a few
>> disks. *They'll be 13-sector, and have a bootstrap that boots on either a
>> 13 or 16-sector drive.
>>
>> Anyone know how this could be pulled off, how one could create their own
>> "universal" disk?
>>
>> -uso.
>
> Probably both DOS's are on the same disk and you get a choice which
> one you want to boot in to. Same idea as a dual boot DOS 3.3 / PRODOS
> disk.
>
> Rob
>

Hm. I don't think so. I've used actual software like this and it's
straight 3.2 (or even 3.1, as in Castle Wolfenstein), apart from having 2
boot sectors.

-uso.

Steve Nickolas

On Sat, 14 Jan 2012, Vladimir Ivanov wrote:

>
> On Sat, 14 Jan 2012, Steve Nickolas wrote:
>
>> I've seen this title applied to something like what I've seen on a few
>> disks. They'll be 13-sector, and have a bootstrap that boots on either a 13
>> or 16-sector drive.
>>
>> Anyone know how this could be pulled off, how one could create their own
>> "universal" disk?
>
> One sector #0 in 13-sector format and one sector #0 in 16-sector format, both
> on track #0?

Right. I'm just wondering how one would arrange that feat.

-uso.

Vladimir Ivanov

On Sat, 14 Jan 2012, Steve Nickolas wrote:

> On Sat, 14 Jan 2012, Vladimir Ivanov wrote:
>
>>
>> On Sat, 14 Jan 2012, Steve Nickolas wrote:
>>
>>> I've seen this title applied to something like what I've seen on a few
>>> disks. They'll be 13-sector, and have a bootstrap that boots on either a
>>> 13 or 16-sector drive.
>>>
>>> Anyone know how this could be pulled off, how one could create their own
>>> "universal" disk?
>>
>> One sector #0 in 13-sector format and one sector #0 in 16-sector format,
>> both on track #0?
>
> Right. I'm just wondering how one would arrange that feat.

Easiest would be creating the track image in memory and writing the whole
track at once with simple routine.

At least the 16-sector boot ROM can load more than one sector, so you
would put few more 16-sector format sectors that hold code/tables that
support 13-sector mode. The rest of the track/disk you make in 13-sector
format.

If the 13-sector boot ROM has similar ability to load more than one sector
initially, the complementary is valid, too.

This should reduce the effort to bootstrap additional sectors from the
booting sector #0 so you can read the "alien" parts of the disk later.

Steve Nickolas

On Sat, 14 Jan 2012, Vladimir Ivanov wrote:

> Easiest would be creating the track image in memory and writing the whole
> track at once with simple routine.
>
> At least the 16-sector boot ROM can load more than one sector, so you would
> put few more 16-sector format sectors that hold code/tables that support
> 13-sector mode. The rest of the track/disk you make in 13-sector format.
>
> If the 13-sector boot ROM has similar ability to load more than one sector
> initially, the complementary is valid, too.
>
> This should reduce the effort to bootstrap additional sectors from the
> booting sector #0 so you can read the "alien" parts of the disk later.
>

Weeeeeeeeell...

Of the first 3 tracks, here's usage for a DOS 3.3 48K slave:

0123456789ABCDEF
0##### ##########
1################
2#####

Would it be possible to change usage to something more like this?

0123456789ABCDEF
0#####
1################
2##### ##########

and then stuff two versions of the first 5 sectors onto the same track 0?
(i.e., a 16-sector version and a 13-sector version).

-uso.

ict@ccess

On Jan 14, 6:32*am, Steve Nickolas
<lyricalnan...@usotsuki.hoshinet.org> wrote:
> On Sat, 14 Jan 2012, Vladimir Ivanov wrote:
> > Easiest would be creating the track image in memory and writing the whole
> > track at once with simple routine.
>
> > At least the 16-sector boot ROM can load more than one sector, so you would
> > put few more 16-sector format sectors that hold code/tables that support
> > 13-sector mode. The rest of the track/disk you make in 13-sector format..
>
> > If the 13-sector boot ROM has similar ability to load more than one sector
> > initially, the complementary is valid, too.
>
> > This should reduce the effort to bootstrap additional sectors from the
> > booting sector #0 so you can read the "alien" parts of the disk later.
>
> Weeeeeeeeell...
>
> Of the first 3 tracks, here's usage for a DOS 3.3 48K slave:
>
> * 0123456789ABCDEF
> 0##### ##########
> 1################
> 2#####
>
> Would it be possible to change usage to something more like this?
>
> * 0123456789ABCDEF
> 0#####
> 1################
> 2##### ##########
>
> and then stuff two versions of the first 5 sectors onto the same track 0?
> (i.e., a 16-sector version and a 13-sector version).
>
> -uso.

I can see how that would work. Each set of 5 sectors would have its
own timing nybbles so that the start of the track would be in
different positions for a 16 sector disk and a 13 sector disk.

Well played

Vladimir Ivanov

Steve,

I am not totally sure what you're after, but if I got your questions
right:


On Sat, 14 Jan 2012, Steve Nickolas wrote:

> Weeeeeeeeell...
>
> Of the first 3 tracks, here's usage for a DOS 3.3 48K slave:
>
> 0123456789ABCDEF
> 0##### ##########
> 1################
> 2#####

Is T0/S5 missing for a reason?

> Would it be possible to change usage to something more like this?
>
> 0123456789ABCDEF
> 0#####
> 1################
> 2##### ##########

Moving part of T0 to T2 is just a matter of loader for booting purposes.
"INIT" would have to be rewritten, but it's screwed anyway since track #0
has to be written with non-standard format.

As we already agreed to, "INIT" is prime sacrifice. ;-)

> and then stuff two versions of the first 5 sectors onto the same track 0?
> (i.e., a 16-sector version and a 13-sector version).

Ok, I guess you want to keep T1..T22 in 16-sector format, only T0 is
funny.

Here's something even more easier to do and maintain:

Put one 16-sector and one 13-sector S0 on T0. Fill the rest of the track
with "macro" sectors encoded in 18-sector format, just as we discussed
recently. The beauty of this approach is that the code in both S0 will be
exactly the same for 13 and 16-sector cases - it will contain loader for
the "macro" sectors from T0. In case 256 bytes aren't enough for such a
loader (and you can't rely on the bootstrap ROM), revert to some simple
scheme, even 4&4. But the layout of 18-sector "macro" sector is very easy
and straightforward.

Again, you write T0 in single pass.


Now, the only problem with this scheme is that you want to have 16-sector
format with 13-sector P5/P6 PROMs on the disk controller. Not reliable and
you can't expect (I think) that users will have lucky combination of
16-sector sequencer PROM and 13-sector bootstrap PROM. (Consult Sather's
"Understanding the Apple II" for details)

So, to be on the safe side, you have to keep the whole disk in 13-sector
format, and the "macro" portion of T0 to be in either something analogous
to 18-sector format but with 5&1 encoding, or plain 4&4 for simplicity.