Ideas for creating disk images of Twiggy disks...

From: Eric Rucker <bhtooefr_at_email.domain.hidden>
Date: Thu, 31 Jan 2008 19:29:29 -0800 (PST)

I was reading some stuff, and got to thinking of various ways to create Twiggy disk images... so I'm joining here and posting them.

I'll note that I don't own a Lisa, and never have. I'm more of an Apple II enthusiast, but all of the early Apple stuff is interesting to me. :)

I'm basing all of this on stuff I've read on various sites, and me guessing at how the Lisa works. I've not actually used one in person, and I've barely used LisaEm. If any of it is wrong, please tell me. :)

My first idea for getting stuff off of Twiggy disks is based on what I had read (on about the Lisa having an Apple II on board to handle the Twiggy. Further reading showed that that's not QUITE right, but... I saw on Ray Arachelian's site that a 6504 with its own ROM was involved in this. I was told by a friend with a 2/10 and various other assorted Lisa parts that the ROMs are socketed.

So, here's theory #1... how hard would it be to interface a Twiggy to an Apple II? Obviously, we're most of the way there if it's already interfaced to the 6504, and I would assume that that ROM handles all of the control... And, once it's hooked to an Apple II, it'd be easy to create a disk image, and get that disk image to another machine.

Theory #2 is more difficult. It would be done without any custom hardware, though.

I read on Ray's site that the Lisa has ROM code to read blocks from the disk. It also has a serial port. I know it also has a ROM monitor. I'm assuming you could execute arbitrary code that you manually key in, using the monitor, just like on the Apple-1 and II... I'm thinking, read the blocks and send them over serial.

Theory #3 is a variation on that theme, except writing to a ProFile, using the ProDOS file format or something. Then, take the drive over to an Apple II with a ProFile card, and copy the image.

Of course, there's a further variation on that theme, again using the ProFile... who said you couldn't cross-compile something to run on the Lisa, then use an Apple II to copy it TO the ProFile, to facilitate copying? That way, you don't have to key it into the monitor every time you want to copy a disk image. And, in case you CAN'T run code keyed into the monitor manually, this handily defeats that, too.

Unfortunately, I know neither 6502 or 68000 assembly, so I can't be of much assistance in actually ATTEMPTING this, but it's all ideas that I just had...

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