[Coco] New trick for nitros9 users

[Mike Rowen]

Just a question. I'm trying to make sure I understand your trick. You  
used minicom to xfer your dsk file to /dd first? Then you copied from / 
dd to /s1, then used ded to update things? Is that correct? I'm not  
setup to do this myself, but I want to learn here. :) Thanks.

-Mike

On Jan 10, 2011, at 1:59 PM, gene heskett <gheskett at wdtv.com> wrote:

> Greetings all nitros9 users;
>
> I cannot write a dsk image on this machine as the FDC in it doesn't  
> know
> what to do with a 256 byte/sector disk, so I must find another way  
> to take
> the code snapshots to my coco.  As a linux user, and having a few  
> serial
> ports available, I can run minicom here and effectively have a text
> terminal here, connected to /t2 on the coco.
>
> To make use of this trick, a 2nd hard drive is needed, I used an  
> elderly
> quantum P40S set as address 1 on the scsi bus as it will need 2 hard  
> drives
> to pull this off.  And of course you will need superdriver-2.1 or  
> drivers
> that work like that does.
>
> I had sent the dw3 .dsks to the coco by first running rz on the  
> coco, then
> doing a ctl_+a, z, s in minicom and selected the dw3 images to send,  
> which
> went with no errors in about 16 minutes an image.
>
> Then I got to thinking about how the partitioning of a drive works  
> on the
> coco when using the superdriver2.1 drivers and wondered if it would be
> possible to access these .dsk images directly without ever making a  
> floppy
> from them, and I couldn't see a reason why not.  So I plugged the  
> quantum
> drive in, and realizing I needed a fully contiguous copy of that dsk  
> to
> pull it off, I set the /S1 descriptor's sas=ff, as high as it would  
> go,
> which on a nearly empty drive, should result in the allocation being  
> made
> far enough into the drive to be contiguous when I copied it from /dd  
> to
> /s1.  That worked, and while filext said there were 2 FD.SEG's used,  
> there
> were no breaks in the file itself.
>
> Another gotcha is that for some reason, the makefiles are writing a  
> bogus
> DD.TOT in these .dsk images, so once it is written in one piece, use  
> ded to
> fix the first 3 bytes, which are written as $004800, indicating that  
> floppy
> is a nearly 5 megabyte capacity floppy, and fix it to be a std 2880  
> sector
> 720k disks DD.TOT.
>
> Then, using filext to determine where the file starts on the disk,  
> like
> this:
> t2|07}/DD/NITROS9/3.2.9:filext /s1
>
> FILES and disk locations in directory /s1
> Filename                      FDsctr LSN sectors LSN Sectors LSN  
> sectors
> ----------------------------- ------ ----------- -----------  
> -----------
> nos96309l2_dw3.dsk            00023A 001000 0800  001800 008E
>
> So the file starts at sector $1000.
>
> But /s1 is a deblocking descriptor, but the values for wpc and ofs  
> in the
> /s1 descriptor are in the drives native sector (512 bytes/sector)  
> counts,
> not in os9 counts.
>
> So next:
> {t2|07}/DD/NITROS9/3.2.9:dmode /s1 wpc=00 ofs=0800
> where the $0800 is half the $1000 that filext reports.
>
> Now:
> {t2|07}/DD/NITROS9/3.2.9:free /s1
>
> "NitrOS-9/6309 Level 2" created on: 2010/12/28
> Capacity: 2,880 sectors (1-sector clusters)
> 16,242 free sectors, largest block 16,242 sectors
>
> So it worked, I can cd to /s1, do a dir -e on it, and run a dsave to  
> make
> the install script that will copy it back to /dd, which is a 1Gb  
> seagate
> drive.  That has now been run, dw3 stuff has been made available so  
> I can
> build new boots with it and continue the conversion to drivewire,  
> and the
> rest of the drive has not been effected, clearing the ofs value  
> restores it
> to its full 40 meg capacity and it still gets a clean bill from  
> dcheck.
>
> And I did it in 10% of the time it would have taken to make a floppy  
> & copy
> it back with dsave as I think I have a squirrelly controller that  
> makes it
> fail to seek properly when writing.  I am not getting good disks after
> track 0 now for some reason.
>
> What's not to like?  Said with a VBWG. ;-)
>
> Your magic trick for this day folks.  Enjoy.
>
> -- 
> Cheers, Gene
> "There are four boxes to be used in defense of liberty:
> soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Perilous to all of us are the devices of an art deeper than we  
> ourselves
> possess.
>        -- Gandalf the Grey [J.R.R. Tolkien, "Lord of the Rings"]
>
> --
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