Re: Apple ][ using PC floppy

[vladitx <vladitx@nucleusys.com>]

On Dec 28, 1:38 pm, David Wilson <mcs6...@gmail.com> wrote:

> To create a volume you need to do two things - low level track format
> to create the raw blocks to be used by the filesystem

That's where I hoped LS 6.0 may do the trick out of the box. Due to
limited experience with ProDOS I was not sure about which tool can do
the initial file system laying out.

> and root
> directory plus bit map creation (plus boot block initialisation for
> bootable disks) which in the case of Disk ][ drives are done by the
> same program {on 3.5" drives the low level format is done by a call to
> the 3.5 ROM firmware). In the early days of ProDOS, you used the FILER
> application to create a new disk and it also needed a single byte
> patch to upgrade it from 35 to 40 tracks (if you had a mixture of
> drives on your system you could have FILER and FILER40 and use
> whichever one you required for the particular drive).

Is there another tool which can do the file system only, w/o low-level
format? Also FILER could be patched to do half-steps.

> > As to the comparison, what about something like this:
>
> > ; on entry A=LSB of block number
> >     LDX $D356 ; get MSB of block #
> >     CPX #$03
> >     BCS X
> >     CMP #$80
> > X: RTS
>
> BCS can be looked at as BHS - Branch Higher or Same. So that would
> test the LSB only if MSB < 3 whereas we want it tested only if MSB ==
> 3.

My original intent was to test "block < $280" (80 tracks x 8 blocks),
as $280 and above are out of range.

> I think you need to do:
>
>     LDX $D356
>     CPX #$03
>     BNE DONE     ; carry clear for 00..02, carry set for 04..FF
>     CMP #$80      ; carry clear for 00..7F, carry set for 80..FF
> DONE
>     RTS

Naughty using of the Z/C flags, I like it.
But isn't $380 a bit too much?

Changing $03 to $02 should make logical equivalent to the above piece
of code, but with a more interesting twist for the reader.

> I wonder if Apple's code is actually
> slower (and less flexible) than this?

Probably, with the excessive sequential tests of X=0, X=1 and then CLC/
SEC.

> So far it looks like no trouble at all. I will have to check out the
> code in FILER and see if the same mod works there.

Hey, thanks in advance. You've got one piece of the converter when
it's produced. Please contact me on email for details.

> P.S. My first IIe was a clone made by Multitech - the MPF-III. It has
> a 40 track 1/2 height 40 track direct drive FDD with an adapter board
> that converts the Apple 20 pin bus into the standard 34 pin bus. It
> uses a couple of one-shots and a PAL to do the conversion.

My solution is similar, except it uses modern HD drives and media.
Everything is packed into a single CPLD (with stabilized oscillator)
which does the pulse conversions between 250 and 500kbit/sec.

I should have shown in the videos that the converting board is plugged
into the regular Disk ][ controller and it's not a slot device with
it's own firmware, etc.
How one could play Karateka or use Locksmith if it wasn't compatible
with Disk ][. ;-)

> P.P.S. If you want to use the full 400KB for DOS, why not make sectors
> 16..31 use the second head of the double sided drive?

Second head will be manually controlled by switches - saves the
physical "flipping" of the diskettes (which is impossible in 3.5"
drives). Remember - this is just transparent device behaving like
regular 5.25" Apple DD diskette and connected instead of the Disk ]
[ drive. One could even use protected software on it, provided he
could write it initially.

I could film running BitCopy on the drive, or even better - write
better description on a webpage.