[Coco] CocoSDC booting OS9

Mon Nov 17 21:29:56 EST 2014

Yeah, the SDC has a 24 bit LBA mode.  BASIC can't reach it inherently.
It's not hard to access from assembly.  Take a look at the OS9
drivers... they are pretty simple... ll_sdc.asm, I believe.   I'm not
sure there's a boot modules for it yet...

On Mon, Nov 17, 2014 at 9:09 PM, Bob Devries <devries.bob at gmail.com> wrote:
> I understood from the documents, that the CocoSDC has an LBA mode. I'm
> assuming that this can be used with large disk images?
>
> I know no more about it other than the one reference in the PDF file.
>
> Regards, Bob Devries
> Dalby, QLD, Australia
>
>
> On 18/11/2014 12:03 PM, 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.
>>
>>
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>> On Mon, Nov 17, 2014 at 6:37 PM, Bob Devries <devries.bob at gmail.com>
>> wrote:
>>>
>>> Unlike Nick, I don't dabble in BASIC. I'm exclusively an OS9 user.
>>>
>>> Tricking the DOS command into thinking that the disk is a *standard* disk
>>> limits the size that the disk can be, because the sector allocation table
>>> starts at sector 1 and continues for 1 byte for every 8 sectors until all
>>> the disk is accounted for. This means that the disk's size *must* have a
>>> sector allocation table of less than 612 bytes. This means that I would
>>> have
>>> a relatively small boot disk, which to my mind is a waste.
>>>
>>> Regards, Bob Devries
>>> Dalby, QLD, Australia
>>>
>>>
>>> On 18/11/2014 8:34 AM, Brett Gordon wrote:
>>>>
>>>>
>>>> Bob:
>>>>
>>>> BASIC can only access so much drive (much less than OS9).  I think the
>>>> SDC docs explain some of the assumptions SDC DOS makes about Large
>>>> Disks.  The DOS command ALWAYS loads the Boottrack from logical Drive
>>>> 0, Track 34, sectors 1-19.  Once the second stage is loaded (BOOT and
>>>> REL, and those fellows)  the entire disk is available.   Its a minor
>>>> problem very similar to Linux's LILO Bootloader had: BIOS limited the
>>>> kernel file to the first 1024 Cylinders.  But after the kernel was
>>>> loaded really big disks where accessible.   I'm assuming the OS9GEN or
>>>> COBBLER take care of making sure the boottrack is where its supposed
>>>> to be at (and marks those sectors as used in OS9 )
>>>>
>>>> Shameless plug:
>>>> Try my boot-trackless booting:
>>>> http://sites.google.com/site/cocoboot2.  Any Nitros9 compiled from
>>>> source in the last couple weeks supports it.
>>>>
>>>> On Mon, Nov 17, 2014 at 4:53 PM, Bill Pierce via Coco
>>>> <coco at maltedmedia.com> wrote:
>>>>>
>>>>>
>>>>>
>>>>> Bob, I think (but not sure), the whole basis of these "big disks" with
>>>>> custom NOS9 boots is that if you're booting from HDBDOS and/or DW4 (how
>>>>> else
>>>>> would you use them?), DW4 doesn't know about disk size (and doesn't
>>>>> care),
>>>>> and as long as the kernel is on track 34 when you type DOS, HDBDOS will
>>>>> load
>>>>> it. For that matter, with a little modding, the kernel can be on disk
>>>>> 255 of
>>>>> an RSDOS/OS9 partitioned drive and still boot :-) After that,
>>>>> RSDOS/HDBDOS
>>>>> is no longer in control and the whole process is determined by the
>>>>> "boot"
>>>>> file in the kernel... be it dw4, becker, cocosdc, superide... whatever.
>>>>> The
>>>>> "boot" for that kernel is setup for that bootfile and it "Just
>>>>> Works"(tm)
>>>>> Ingenious I tell ya... FREAKIN INGENIOUS!
>>>>>
>>>>> BTW... I was told not to worry about stuff like that... that it was
>>>>> just
>>>>> Majic and not to question it or it would go "poof!".
>>>>>
>>>>>
>>>>> Bill Pierce
>>>>> "Today is a good day... I woke up" - Ritchie Havens
>>>>>
>>>>>
>>>>> My Music from the Tandy/Radio Shack Color Computer 2 & 3
>>>>> https://sites.google.com/site/dabarnstudio/
>>>>> Co-Webmaster of The TRS-80 Color Computer Archive
>>>>> http://www.colorcomputerarchive.com/
>>>>> Co-Contributor, Co-Editor for CocoPedia
>>>>> http://www.cocopedia.com/wiki/index.php/Main_Page
>>>>> E-Mail: ooogalapasooo at aol.com
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: Bob Devries <devries.bob at gmail.com>
>>>>> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
>>>>> Sent: Mon, Nov 17, 2014 4:02 pm
>>>>> Subject: [Coco] CocoSDC booting OS9
>>>>>
>>>>>
>>>>> Hi all,
>>>>>
>>>>> I don't have my CocoSDC yet.... (soon!)
>>>>>
>>>>> I was looking through the NitrOS9 repo and found a disk image which can
>>>>> be used with it. I was surprised to see that even though it's a ~4.5MB
>>>>> disk, it can still boot OS9 without any extra disks.
>>>>>
>>>>> Now that makes me wonder what the largest size a disk can be and still
>>>>> be bootable under the current boot method. The limitation would seem to
>>>>> be $0264 sectors for the sector allocation table, since the DOS command
>>>>> gets the kernel track from there (34 tracks * 18 sectors = 612
>>>>> ($0264)).
>>>>>
>>>>> Perhaps the "DOS" command could be made more intelligent by having it
>>>>> check the size of the disk by grabbing the first three bytes from LSN0,
>>>>> and then subtracting 18 sectors, and load the kernel track from there,
>>>>> thus putting the kernel out of the way of the sector allocation table,
>>>>> and thereby allowing for almost any size (hard) disk.
>>>>>
>>>>> One gotcha would be if the file system used a cluster size of more than
>>>>> 1, which would make the allocation of the kernel's sectors in the
>>>>> sector
>>>>> allocation table a bit more curly.
>>>>>
>>>>> Chris Burke used a method by which track 128 of the drive was used as
>>>>> the kernel track, but IIRC it could be changed. He also had utilities
>>>>> to
>>>>> allocate the sectors in the sector allocation table.
>>>>>
>>>>> My $0.02
>>>>>
>>>>> Regards, Bob Devries
>>>>> Dalby, QLD, Australia
>>>>>
>>>>> --
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>>>>> Coco at maltedmedia.com
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>>>>>
>>>>>
>>>>>
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>>>>
>>>>
>>>>
>>>>
>>>
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>>
>>
>>
>
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-- 
Brett M. Gordon,
beretta42 at gmail.com