[Coco] Coco Digest, Vol 56, Issue 24

[carl j england]

> 
> Message: 4
> Date: Thu, 14 Feb 2008 16:05:25 -0600
> From: "CoCo Mongrel" <cocomongrel at googlemail.com>
> Subject: [Coco] Getting more out of floppy disks
> To: coco at maltedmedia.com
> Message-ID:
>         <bf35da7d0802141405o18edb027n55aa98aec228ba62 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
> 
> So for the game I'm working on, I'd like to get as much out of a 
> single
> floppy disk as I can without wasting a lot of CPU or memory on 
> complex
> compression algorithms.  I would like to provide the option for 
> those who
> have more modern floppy drives or hard drives with multiple RS-DOS
> partitions to use them to store lots of game data.
> 
> I have 80-track (3.5") drives on my CoCo, but they're being used as 
> 35-track
> double-sided drives.  I still prefer the 720K floppies, even though 
> there's
> a lot of waste (though I do use the full capacity in OS-9) because 
> data
> transfer with modern PCs is easier using 3.5" disks.
> 
> I know there are DOSes, and patches to stock RS-DOS that go from 35 
> to 40
> tracks, and that allow you to map the second side of the disk to 
> otherwise
> unused drive numbers (e.g. 2,3).  But on 80 track drives, that still 
> only
> uses half of the disk.  My understanding is that BASIC's FAT buffer 
> would
> have to be expanded in order to use 80 tracks (or something like 
> that).  But
> how difficult would it be to make DECB treat track 40 as track 0?  
> That way
> you could have a whole upper bank of 40 tracks on each side of a 
> disk.  The
> inconvenient part would be that you'd have to poke a bunch of 
> changes back
> and forth to switch between the lower bank and the upper bank, so 
> it
> wouldn't be well suited to everyday interactive use.  But it 
> wouldn't be at
> all difficult to make a BASIC program keep track of which bank you 
> were in,
> and just have a subroutine to patch DECB for the lower or the upper 
> 40
> tracks as necessary.  Or am I fooling myself about how difficult it 
> would be
> to get BASIC to add 40 to its tracks?  Any thoughts?
> 
> CoCoMongrel
> 
> 
> ------------------------------

Use Super Boot.  It is public domain (i wrote it) and available on coco
web sites.
it gets around the 40 track limit by relocating the fat to a new address
in high ram.
it supports four single sided 80-track drives or two double-sided drives
(drive 2 is back of drive 0--drive 3 is back of drive 1)
you install Super Boot on track 34, sectors 1 thru 9.  to use it, just
type "dos"
if you have a startup file set up (basic or m/l), the program will
auto-execute;
otherwise, you will be presented with a directory list.  select a file
and press "enter" (or "space") to load.
also, you can set up the boot to run the coco3 in double-speed mode
(automatically switches to slow when accessing the disk drive--then
switches back)
you would lose 1 granule of storage space on one disk, but the added 40
tracks would be worth it.

***note*** for those already using Super Boot.
    if you have your boot disk in drive 1, you can type "dir1:dos" to
boot.  (if you get an i/o error, then some of the files are crossing the
35 track boundary and 
    have confused the "dir" command.  just type "dos" and the boot will
continue from drive 1)
***note*** the "dos" command always acts on the last accessed drive
regardless of which is your current default drive.