Twiggy 128K prototype, again.

[barana]

ok thx guys, appreciated. Tho, waste basket is used in non american macos. Many copies of sys6 and 7.x have passed under my mousecurser as wastebasket.check it out.

I wonder for kicks, a dd 5.25 can be formatted to 360kb maybe with hfs? the apple II crowd can hook up a 3.5 drive to a ][ and use it as a 5.25. its been done, maybe in reverse, just for kicks ur disk][ mac might work with mfs/hfs, trash80tohpmini.

 

[LCGuy]

I thought that was only in British versions? Here in Australia we got the US versions, complete with the Trash.

 

[Ike]

Okay guys thanks for the info. sorry for making stupid assumptions.

 

[onlyonemac]

I'm sure the linked video's fake.

1. The UK version had "Wastebasket", not "The Wastebin" (and why would the supposed version in the video be UK anyway?)

2. The twiggy disk icon does not match others seen before

3. Early Macintosh OS versions (pre-release versions) had "@", not an apple, in the corner of the screen

4. Slomacuser has already checked it in ResEdit

Let's get this one out of the question and carry on!

 

[onlyonemac]

Just had another thought...

Why does everyone here assume that the twiggy and the sony drives need different drivers? If they're both 20-pin, then most likely they're both interfaced in the same way. The question is the disk that was tried.

What we need is to write a Macintosh system disk image to a twiggy disk (probably using a Lisa/custom interface to spare twiggy drive) and then try it out in the twiggy drive on this Mac.

To me, I'm of the opinion that it's a genuine prototype. Where else would an otherwise unheardof 20-pin twiggy drive have come from? I think we need to contact mactwiggy over on applefritter and find out the contact details of the guy he says he bought it from. If anything, I think mactwiggy's conscience would have gotton to him before he sold it, so I don't think he's to blame. We need to get hold of the guy he bought it from.

 

[Gorgonops]

Why does everyone here assume that the twiggy and the sony drives need different drivers? If they're both 20-pin, then most likely they're both interfaced in the same way. The question is the disk that was tried.

They physical geometry of Twiggy vs. Sony is completely different. A Twiggy has 55-ish data tracks per side with non-opposed heads and rotates at a lower speed than the Sony drive, which has 80 tracks and only one head. The rotation speed difference means Twiggy puts more data on each track than the Sony, which is why its storage capacity in 110 tracks is slightly more than what a GCR-encoded double-sided 3 1/2 drive manages in 160 total tracks, and way more than the single-sided Sony's 80 tracks. So between the different track sizes, number of tracks, and double vs. single sided, yes, you would need a different driver to handle a Twiggy than a Sony even if the interface were completely electrically compatible between the two.

The outstanding question was whether the ROM version in that particular Mac had a driver that could handle a Twiggy. The question is "legit" given that the onscreen disk icon is a picture of a Sony, and would help determine if it was a working unit as-is or if it were possibly thrown together from leftover parts.. (If there's some way to use the sense lines to tell the difference between a Sony and a Twiggy it's certainly possible the ROM's driver could support both. We don't have enough information to know if that's true or not, as we have *zero* documentation of that "Mac Twiggy" mechanism and as far as I know there's no dump of the machine's EPROMs.)

 

[onlyonemac]

Surely any drive interface differences would be handled at the level of the drive controller, and not affect the OS in any way?

 

[Gorgonops]

Surely any drive interface differences would be handled at the level of the drive controller, and not affect the OS in any way?

No. Read the documentation on how the IWM drive subsystem works and you'll see that is a manifestly false statement. The IWM disk controller (and by extension the attached device) is very "dumb" and *entirely* driven by software running on the main CPU in both Macs and the preceding Apple II's. (It amounts to little more than a shift register and a few latches.)

It may be worth noting that the IWM driver in the shipping Mac ROMs is actually *called* the ".sony" driver. (It's modular enough that it can be overridden and replaced by a driver resident in memory; that's what the floppy that enables the HD-20 IWM-driven hard disk does on the 64K ROM-ed Mac.) I don't recall for sure, but I *think* the icon for the floppy disk drive is embedded inside said driver. (been a while since I poked through a disassembly of said ROM.) So for the Twiggy drive on that unit to be functional *and* for it to have a picture of a 3 1/2 floppy as the startup icon the only possibility is there were some interim ROM versions where a former ".twiggy" driver incorporated Sony support or ".sony" kept legacy Twiggy compatibility that was stripped out in the last moments before shipping.

 

[onlyonemac]

Or even left in after shipping; who knows???

 

[Gorgonops]

Or even left in after shipping; who knows???

Enough people have eyeballed that driver that someone probably would have noticed and called out the presence of any leftover Twiggy support, but sure, why not, maybe it's cleverly hidden in there. Broadly speaking, *IF* the PWM signal that controls the drive speed were compatible between the two systems (which is a huge if, the Sony drive rotates *almost* but not exactly twice as fast as the Twiggy so they're not really going to match up by an even fraction) it might be possible for the system to read the first sector off either sort of drive and, based on a data structure in it, adjust its behaviour accordingly. So in theory it *just might* be possible for a shipping ROM to boot off a properly formatted Twiggy disk that has that magic number in its boot sector without leaving much of a signature in the ROM driver. Feel free to learn enough 68k Assembly to examine the shipping ROM's boot-time behaviour and ascertain if that might be true.

 

[Bunsen]

If they're both 20-pin, then most likely they're both interfaced in the same way.

I see you've never plugged a PC parallel port device into a SCSI port by mistake. The tiny mushroom cloud was quite impressive.

 

[onlyonemac]

I don't really have parallel or SCSI devices (apart from a dead internal HD), but do they use the same size connecter?

 

[Trash80toHP_Mini]

Yep, lots of stuff uses the DB-25 one way or another. Apple should NEVER have used it for SCSI.

 

[Gorgonops]

Forget Parallel vs. SCSI's potential for 'splodiness, Apple themselves used the same 19 pin external connector for a whole slew of incompatible floppy drives. *Most* incompatible combinations won't do worse than "not work", but there are exceptions. Connecting almost any Apple II floppy to a Mac's external floppy port is an easy-peasy way to blow up the IWM, and conversely the PWM signal present on the early Macs' floppy connector can damage certain newer drives. (Or again, damage the Mac if it's shorted.) Worse yet, some of the damage potential for mismatched drives is actually due to software issues, because the IWM (and Apple's floppy cabling) uses the same set of wires in two completely different ways depending on if the drive is "dumb" (Most of Apple's 5 1/4" drives) or "mostly dumb" (the rest). The IIgs uses the same controller as the 128k->Plus Macs and can accommodate almost every Apple floppy drive ever made mostly because its driver software is aware of the differences while the Mac's isn't.

So, yeah, it's pretty silly to assume that simply because that Twiggy mechanism uses the same 20 pin connector as the 3 1/2 drive it's 100% software compatible.

 

[Mk.558]

And that's before we get to DE-9...

 

[Mac512k]

It's alive!...

I hope the following will set the records straight. Some may know me as eBay seller "wozniac". I just want you let you all know that over the past year I have exausted many resourses and went as far as I could go in order to facilitate the resurrection of this Twiggy Macintosh 128k prototype. To everyone's delight, yes - it lives! 2 disks were found.

I was able to have the disks shipped up to me in Canada, then sent over to James McPhail who was able to archive and duplicate the disks by means of the Basic Lisa Utility which he wrote. This is a truly amazing feat and discovery. I wish to share all of this with you.

More stories and information to come, This is "insanely great"...

Steve Sez...!

 

[Arths]

This is absolutely amazing, a true piece of history 8-o

Thanks for everything, if you could make a video of it running it would be stunning :b&w:

Would be awesome to run this in an emulator ain't it ?

 

[Brooklyn]

This is so cool. Who had the Mac Twiggy disks? An ex Apple employee?

 

[Macdrone]

So what was the software version? Think if we put it on a 3.5 that a 128 would work? Anyway to get a copy? Thanks for the updates so far.

 

[Mac512k]

From what I have discovered, the Apple Twiggy 5.25" and the Sony 3.5" drives were completely incompatible. Should you plug in a 3.5" Sony drive into a Twiggy Macintosh, it will surely nuke the drive. The Twiggy 5.25" and Sony 3.5" disk drive formats were both exparimented with and developed on the Lisa initially. The Macintosh was a simplified verstion of the Lisa. Given that it's file formats ware completely different, All of the original Macintosh software was in fact originally coded and written on the Lisa.