Re: Copying Mac MFS disks on an Apple II

[Eric Smith <eric-no-spam-for-me@brouhaha.com>]

"Bill Garber" <willy46pa@comcast.net> writes:
> I was going to say that I just snagged one of those drives on eBay,
> but it isn't here yet. I was hoping to see if I can write 400k disks on

A Macintosh 400K drive will not work on an Apple II with any of the Apple
disk controllers, nor with most third-party controllers.  I seem to recall
that there was at least one third-party controller that could handle the
400K drive, but I don't recall the company or product name.

The 400K drive needed a PWM motor speed control signal that was generated
by the original Macintosh in basically the same way the Macintosh produced
sound: during horizontal retrace, the video logic read bytes from the
sound and disk motor speed buffer and loaded it into a counter to produce
PWM.

The Apple II disk controllers don't do this, nor do most Macintoshes after
the Mac Plus.  I'm not sure if the Macintosh SE or Macintosh Classic
have the motor speed control, but none of the Macs that use a 68020,
68030, 68040, or any PowerPC have it.

The 800K and FDHD/Superdrive (1440K) drives control their own motor speed.

The Lisa 2 and 2/5 (models with no internal hard drive, as opposed to
the Lisa 2/10 and Macintosh XL) have a special adapter board ("Lisa Lite
Adapter") mounted in the drive cage with a few chips that generate the
motor speed PWM signal under control of the 6502 on the Lisa I/O board.
This was needed because the I/O board was designed for the Twiggy disk
drives which had the motor speed control in the drive.  For the Lisa 2/10,
the I/O board was redesigned and included the 400K speed control.