[Coco] Nitros Partitioning Was: CoCo SDC and others

[Gene Heskett]

On Wednesday 08 March 2017 10:56:47 Brett Gordon wrote:

> Nitros is awesomely flexible unto itself.  It needs a little help with
> sharing the hd though.
>
> Gene: how about lsn 1?  MBR likes the last half (or so) of that
> sector.  My ccpt and taylor's partitioning want all of sector 0.  The
> last half of sector zero is not really helpful.
>
LSN1 is the beginning of the file allocation table, which may be up to 
256 sectors long since the limit is 65,536 bytes for that. That, and the 
first half of LSN0 are sacrosanct without a huge rewrite.  That fat 
allocations variability is why the address of the root directory's fd 
sector is in LSN0.  What you want to sounds like treading on sacred 
dirt, so lets hear it in greater detail.

> We dont have to make nitros read and apply the table.  Lets just add
> an offset to each sector access in the fpga's sd driver.  We'll trick
> nitros into beleiving sector 256 is actually sector 0 :)  This
> platform will greatly benefit from this change.  And its such a bloody
> simple change. I can/will do the work and sumbit the work to Tormod. 
> he, justly so, takes heed of the list's input, so lets have a good
> discussion about it!
>
> I'm not asking nitros to actually read, write, or apply the table to
> it's descriptors.  Thats a bigger project, as boisy's superdriver
> could be used to apply this.   Or the boot/init code could call a
> module to noodle with wps/ofs of matching descriptors.
>
> "OSes of the CoCo Unite!  Throw off the chains of os9 oppression!  Let
> the people seize control of their own equipment.  Let there be
> partitioning!" - Comrade Tyranous, the Red ( blue, and green) Leader
> of the People.
>
> ;)  cheers!
>
> brett
> On Mar 8, 2017 7:38 AM, "Gene Heskett" <gheskett at shentel.net> wrote:
>
> On Wednesday 08 March 2017 01:34:04 Brett Gordon wrote:
> > On Mar 7, 2017 7:52 PM, "Ron Klein" <ron at kdomain.org> wrote:
> > > If you decide to use YA-DOS with the CoCo3FPGA, you will need to
> > > flash it to the same bank that you use for Brett's NitrOS9 SD
> > > loader.  That flash slot on the CoCo3FPGA is reserved for
> > > alternate DOS's and can accommodate 16K roms like YA-DOS.  I'm not
> > > sure how the NitrOS9 SD boot loader works, but perhaps we can see
> > > if Brett is able to incorporate that boot loader into YA-DOS for
> > > those using a CoCo3FPGA.
> >
> > Yeah, the ROM-able nitros boot loader will have to be replaced with
> > ya-dos.  But no worries: There's a decb loadable .bin file in the
> > nitros9 repo that'll load up nitros too.  I think invoking 'make'
> > just right will pop out a .dsk file.  Just get that image copied
> > over. Yados can copy the dsk from DW to the SD card.
> >
> > Nitros has no partitioning.  That needs to change.  Maybe we can
> > just hack a offset into Gary's nitros drivers, and force nitros to
> > skip a few sectors to allow for a real partition table.
> >
> > brett
>
> Yes it does Brett, and it works just fine. So let me step up to the
> podium and preach a bit here.
>
> One of my HD's is setup for an os9 allocation/partition of just under
> 500 megs starting at LSN0. By inserting a sector offset that starts
> with the next sector above that which is in DD.SIZ in LSN0, and some
> trickery involving the dmode stp setting, this is how we do the 256
> virtual 35 track SS floppies on the next 80 some megabytes after the
> end of the os9 allocation.  My /sh descriptor is setup to do exactly
> that. stp is byte wide, so setting its number to anything, $00 to $FF
> is one of the 256 of these virtual floppies.
>
> Not enough? copy the sh.dd file to si.dd, use ded to change its name
> to si internally, and adjust the offset in ofs and wpc to point at the
> next startng sector after the end of those 256 vdisks, and do it
> again. Wash, rinse & repeat for a third set of 256 vdisks named /sj,
> /sk, /sl etc. Since that is a 1Gb drive, if I was so inclined, I could
> do it several more times before I was out of drive, but I'd be totally
> out of system ram long before I was out of drive.
>
> As for an LSN0 based partition table I don't recall a thing that makes
> use of anything past offset $6F, so there is no reason we couldn't
> implement that 5 bytes at a time in this unused space, for a partition
> table, 3 for offset, 2 for size exactly as laid out in the first $20
> bytes of lsn0 now. One could allocate one more byte per partition for
> the cluster size, thereby eliminating the nominally 131 megabyte limit
> per partition so added.
>
> It could be done, using a mount command that looked up the proper
> offset from that table, and installed it in just one descriptor, maybe
> 2 if you wanted to do a partition to partition copy without using the
> base partition as a scratchpad buffer.  That would certainly save some
> system ram by getting rid of those data tables in memory, at IIRC, $27
> bytes a path descriptor in the boot file. That would require this new
> mount command needing 2 arguments, the descriptor to modify, and the
> partition to set it to.
>
> Regardless of how its done, present way, or by looking it up in LSN0,
> we have an ability to do partitioning just by taking advantage of what
> we have right now.
>
> The problem? It's differing individual setups because no 2 of us have
> identical drive setups. Except for a vanishingly slim chance at the
> fests, we'll never have identical setups on adjacent tables.
>
> But drivewire removes that limitation by putting the differences in
> the descriptor being accessed.
>
> I would investigate, for purposes of moving stuff around at the fests,
> the probability of setting up a central drivewire server, and with a
> 10 meter usb extension cable such as I use, so my drivewire setup is
> actually a usb-2 circuit, and if DW can make use of 2 different ports,
> I don't know that it can, one could publish his latest whiz-bang
> package to everyone in the room in 45 minutes of carrying the cable
> from machine to machine. If DW could be convinced to sit there and
> wait for the cable to be plugged into the next machine without a
> complicated kill and restart as the cable was moved to the next
> machine, that would be cut to 15 minutes.
>
> Or, if DW will run on the debian jessie installed on an r-pi3, and
> mount the r-pi on a 6 volt jel-cell, it could be carried from table to
> table and short cables used, negating the need for that $40 10 meter
> extension cable, just a good usb to coco drivewire cable 4 or 5 feet
> long. Drivewire works just fine over usb in the middle of its cabling
> useing a /dev/ttyUSB# port on this linux box.  My long cable is
> plugged into a usb port, on a hub this box drives, the far end of that
> cable is plugged into a 7 port hub on the coco3's desk, and a usb to
> drivewire cable is plugged into that 7 port.
>
> The coco3's printer can also be plugged into this same hub, and has
> been up until we had the basement work late done last spring. But
> since that printers other main job is keeping the LinuxCNC
> configuration listings on my machines up to date, I moved it up to
> here so I don't have to coerce these ancient legs down and back up a
> flight of stairs to get a fresh printout. That has been quite handy,
> and when I bring my coco3 back to life, I may just go get another of
> these brother $110 black and white laser printers and put it on the
> top shelf of the coco3's desk where this one lived for several years.
> It will be just another printer to cups in the localhost:631/printers
> display. And the coco is pleased either way as its a 19 page a minute
> printer, and the typeface can be any font loaded. To me, the default
> is such an improvement in readability compared to an old DMP thats its
> beautyfull.
>
> Whats not to like?
>
> Its called making use of the resources we already have in the nitros9
> world. I hope this "sermon" is helpfull. ;-)
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Genes Web page <http://geneslinuxbox.net:6309/gene>
>
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Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>