Using an Apple II to write a Commodore 64 disk

[Brian J. Bernstein]

Hi,
It is well known that the Disk II controller is extremely flexible as Woz made the design software-driven. In fact, I've read stories about how at least one software publisher used to use an Apple II to copy protect software for the Atari 8-bit series because of this flexibility.

I've recently brought an old C64 back into service (yes, a new and reliable power supply is being used!) and I'd like to download software from the internet to run on the machine. However, I'm looking at options that would utilize my 1541 drive before dropping $160+ on somewhat the equivalent of a CFFA3k.

Has anyone ever made a program that would allow an Apple II to write a C64 disk?

I know that the Disk ][ did MFM encoding and that the 1541 did GCR, but would it be possible for an Apple to write a d64 image to a disk? I'm not looking for the Apple to be able to make sense of it or read a C64 disk, just write an image and be done with it.

Is this possible and has anyone ever done anything like that?

thanks

[Antoine Vignau]

Hi Brian,

There were pro solutions like ones from Alf to write C64 disks but they are very hard to find.
Apart from the GCR/MFM thing, you cannot write a C64 disk with an Apple II for one simple reason: the drive speed is always the same on the Apple II disk drive whereas it is variable on the C64.
--
Antoine

[Steve Nickolas]

I think they both use GCR.

Anyway, IIRC, Burger Becky said once that she had figured out a way BITD
to hook a 1541 to her Apple IIgs, using her contraption in the process of
porting "Tass Times in Tonetown" along with a C64 version of ProDOS-8.
(Indeed, the C64 "Tass Times" disk images do contain a ProDOS filesystem.)

-uso.

[Michael J. Mahon]

I know that the Disk ][ did MFM encoding and that the 1541 did GCR,...

Actually, the Disk ][ encoding is GCR, encoding 6 data bits in 8-bit
nibbles. Address marks are FM encoded (4 bits in each 8-bit nibble).

[Scott Alfter]

Post by Brian J. Bernstein
I know that the Disk ][ did MFM encoding

Nope. Woz implemented GCR on the Disk II. What will be the problem is that
Commodore's 5.25" drives implemented variable rotational speed to cram more
blocks into the outer tracks. Apple didn't do that until it introduced its
3.5" drives.

_/_
/ v \ Scott Alfter (remove the obvious to send mail)
(IIGS( https://alfter.us/ Top-posting!
\_^_/ >What's the most annoying thing on Usenet?

[b***@gmail.com]

Post by Scott Alfter

Post by Brian J. Bernstein
I know that the Disk ][ did MFM encoding

Nope. Woz implemented GCR on the Disk II. What will be the problem is that
Commodore's 5.25" drives implemented variable rotational speed to cram more
blocks into the outer tracks. Apple didn't do that until it introduced its
3.5" drives.

Weren't the C64 floppies also 40-tracks? If not, and they were only 35 like the Apple II, would it then somehow be possible to write the C64 disk contents out onto a 40-track constant speed Apple II GCR drive and still have it be readable by a 1541 C64 which might be able to read the extra tracks?

[Michael J. Mahon]

Post by b***@gmail.com

Post by Scott Alfter

Post by Brian J. Bernstein
I know that the Disk ][ did MFM encoding

Nope. Woz implemented GCR on the Disk II. What will be the problem is that
Commodore's 5.25" drives implemented variable rotational speed to cram more
blocks into the outer tracks. Apple didn't do that until it introduced its
3.5" drives.

Weren't the C64 floppies also 40-tracks? If not, and they were only 35
like the Apple II, would it then somehow be possible to write the C64
disk contents out onto a 40-track constant speed Apple II GCR drive and
still have it be readable by a 1541 C64 which might be able to read the extra tracks?

No, because the bit rate would be wrong.

[Tony Cianfaglione]

I maintain an old legacy archive at:

https://www.chebucto.ns.ca/Services/PDA/PDA.html

which may or may help you.

---

Post by Brian J. Bernstein
Has anyone ever made a program that would allow an Apple II to write a C64 disk?

[Tony Cianfaglione]

I maintain an old legacy archive at:

https://www.chebucto.ns.ca/Services/PDA/PDA.html

which may or may not help you with this.

---

Post by Brian J. Bernstein
Has anyone ever made a program that would allow an Apple II to write a C64 disk?

[Bill Buckels]

Post by Brian J. Bernstein
However, I'm looking at options that would utilize my 1541 drive before
dropping $160+ on somewhat the equivalent of a CFFA3k.

I use an MMC Replay right here, which I think is no longer available... and
you are right about what this type of adapter is worth these days... but
check-out the zoom floppy... it looks like it might work...

http://store.go4retro.com/zoomfloppy/

Some discussion on lemon64...

https://www.lemon64.com/forum/viewtopic.php?t=61058&start=0

Regards,

Bill

[Bill Buckels]

Post by Brian J. Bernstein
However, I'm looking at options that would utilize my 1541 drive before
dropping $160+ on somewhat the equivalent of a CFFA3k.

Here's links to another lower cost solution than the 1541 Ultimate or MMC
Replay...

Sd2iec SD Card Reader for Commodore 64 1541 Disk Drive Emulator C

https://www.ebay.com/p/1773138060

How to Copy C64 Disks between SD2IEC and Real Drives

Regards,

Bill