Create Amiga diskettes on Mac

[M.O.B. i L.]

Is it possible to create bootable Amiga-diskettes on a Mac68K? What
software on the Mac should one use?

[.]

Post by M.O.B. i L.
Is it possible to create bootable Amiga-diskettes on a Mac68K? What
software on the Mac should one use?

I don`t think there is any way, or support
of doing what you`ve asked.

There are however multiple options on a
PC; which you no doubt have.

Catweasel::
http://www.vesalia.de/e_catweaselmk4plus.htm

MPDOS PRO
http://www.krishnasoft.com/sps.htm

Winuae (Amiga emulator)
http://www.winuae.net/

If your amiga has a harddrive, you
can attach this to your PC and intall it
through winuae (linux, 2k/xp required)
Then re-attach to your amiga.

Then network your PC to the amiga
with Amiga Explorer:
http://www.amigaforever.com/ae/

And then read and write amiga disks
to your hearts content. :)

[Thomas Richter]

Post by M.O.B. i L.
Is it possible to create bootable Amiga-diskettes on a Mac68K? What
software on the Mac should one use?

Likely not. The Mac DD drives use many tricks, like making the rotation
speed depending on the track, and this is very much incompatible with
the Amiga layout. Even more, Amiga uses a custom track format that is
not compatible to that of common controllers.

So long,
Thomas

[M.O.B. i L.]

Post by Thomas Richter

Post by M.O.B. i L.
Is it possible to create bootable Amiga-diskettes on a Mac68K? What
software on the Mac should one use?

Likely not. The Mac DD drives use many tricks, like making the rotation
speed depending on the track, and this is very much incompatible with
the Amiga layout. Even more, Amiga uses a custom track format that is
not compatible to that of common controllers.

I've read in a Swedish usenet groups (se.dator.sys.amiga,
swnet.sys.amiga) that an old Mac could write the first track in
Amiga-format. He didn't remember what program he used on the Mac though
but had used it himself to transfer small files.

[Mikael Fors]

Post by M.O.B. i L.

Post by Thomas Richter

Post by M.O.B. i L.
Is it possible to create bootable Amiga-diskettes on a Mac68K? What
software on the Mac should one use?

Likely not. The Mac DD drives use many tricks, like making the rotation
speed depending on the track, and this is very much incompatible with
the Amiga layout. Even more, Amiga uses a custom track format that is
not compatible to that of common controllers.

I've read in a Swedish usenet groups (se.dator.sys.amiga,
swnet.sys.amiga) that an old Mac could write the first track in
Amiga-format. He didn't remember what program he used on the Mac though
but had used it himself to transfer small files.

You can't use a Apple 800k drive to make Amiga disks. Amiga uses a completely different type of approach. The Apple 800k drive also uses variable speeds to make it even worse.

Likewise, a PC uses hard index (rotation signal pulse) for sectoring.

The Amiga uses a syncword ($4489) which is equal to MC680x0 ILLEGAL instruction. That's why Amiga drives unlike a PC, in SD (Single density) fits 880k vs a PC's 720k (raw data, excluding filesystem) and a HD (High density) fits 1.76MB vs a PC's 1.44MB.

There IS hardware differences between Amiga and PC floppy drives, but there exists hardware, as previously mentioned, that can be used to read and write disks to and from native Amiga, like CatWeasel

[Thomas Richter]

Post by Mikael Fors

Post by M.O.B. i L.
I've read in a Swedish usenet groups (se.dator.sys.amiga,
swnet.sys.amiga) that an old Mac could write the first track in
Amiga-format. He didn't remember what program he used on the Mac though
but had used it himself to transfer small files.

You can't use a Apple 800k drive to make Amiga disks. Amiga uses a completely different type of approach. The Apple 800k drive also uses variable speeds to make it even worse.
Likewise, a PC uses hard index (rotation signal pulse) for sectoring.

A PC *may* use the sync pulse. Otherwise, PCs use MFM encoding very much
like the Amiga does, except that the sector encoding is different, and
the gap between sectors is in general larger.

Post by Mikael Fors
The Amiga uses a syncword ($4489) which is equal to MC680x0 ILLEGAL instruction.

$4489 is not an 68K illegal instruction (that would be 0x4afc). It is a
sync word that cannot be created by any data using the MFM encoding.
Actually, PC controllers use the same sync word.

Post by Mikael Fors
That's why Amiga drives unlike a PC, in SD (Single density) fits 880k vs a PC's 720k (raw data, excluding filesystem) and a HD (High density) fits 1.76MB vs a PC's 1.44MB.

Actually, the reason for that is that the PC has a larger gap between
sectors. The Amiga encodes an entire track in one go, then writes it to
the disk, using the blitter and the CPU. The PC has a dedicated
controller which does the encoding and decoding, and can address
sectors. The sector gap is larger to allow it to pick out an individual
sector, something the Amiga does not do.

Post by Mikael Fors
There IS hardware differences between Amiga and PC floppy drives, but there exists hardware, as previously mentioned, that can be used to read and write disks to and from native Amiga, like CatWeasel

A lot of "mix-up" here. Yes, there are differences between Amiga and PC
drives, but these are minor and irrelevant for the encoding. It's mostly
related to how diskchange operates and how the motor is controlled. A
selection of PC drives can be modified to fit into the Amiga just by
picking up the necessary extra signals from the ICs.

The real difference is in the controller. The Amiga does not have a disk
controller. Everything happens in software, with a little help from the
custom chips: Positioning the drive head, encoding and decoding the MFM
data is all done in software. The PC has a more advanced dedicated
floppy disk controller, typically part of the southbridge, which is
programmed by higher-level instructions like "read that sector from disk
and place it in this memory buffer". The MFM encoding and the
track-layout is defined by this chip.

Greetings,
Thomas