At 7:05 PM +0100 4/13/12, Adrian Graham wrote: I've sure never seen anything like that. I'd say that the 'beyond rare' might not be hype, but honestly don't know. Zane -- | Zane H. Healy | UNIX Systems Administrator | | healyzh at aracnet.com | OpenVMS Enthusiast | | | Photographer | +----------------------------------+----------------------------+ | My flickr Photostream | | http://www.flickr.com/photos/33848088 at N03/ |

On Apr 13, 2012, at 2:42 PM, Eric Smith wrote: I'm sure it's rare, but $99,995.00 rare? I doubt it. That's two to three times what the typical functioning Apple I goes for. - Derrik

Jules Richardson wrote about the Twiggy Mac: They don't. But in the 29 years since they were made, there's no indication that a complete unit has ever turned up for sale before, nor anyone publicly stating that they have one. It's unclear how many of these were made, but probably not too many, and of the few that ever left Apple's hands, most were probably returned to Apple and either modified to use the 3.5-inch drive, or destroyed. It is certainly far more rare than an Apple 1. If there are any others left out there, they're well-hidden.

Geoff Reed wrote: It's a lot, but given what the less rare Apple 1 sells for, possibly not completely unreasonable. It's hard to say. I suspect that it might boot from an external 400K drive. Obviously that's not very interesting, other than perhaps providing a diagnostic for all of the hardware other than the Twiggy drive. Eric

On Apr 13, 2012, at 2:27 PM, Sam Onella wrote: I just can't see having a system, no matter how rare that one would not be able to use. leaving it to bit rot seems a very sad thing to do....

On 04/13/2012 02:55 PM, Dave McGuire wrote: How do you "fix" not having an OS that will run on it? By writing one yourself? By hacking a released version of MacOS to run on it?

On 4/13/12 4:22 PM, Dave McGuire wrote: Not really. I said at the time it surfaced that Dan Kottke would probably be the only person who might have an OS on twiggy floppies. The version of Inside Mac I scanned a few months ago mention the twiggy disk driver, but that all disappeared after the switch to Sony drives in mid 1983, and the floppy chapter talks only about the .Sony driver.

On 2012 Apr 13, at 1:51 PM, Eric Smith wrote: Is anything known about the provenance of this unit? The last photos in the ebay listing appear unrelated, or should I say misleading (the rear with the "Dan Kottke" mention is not the same machine, the jagger note, etc.). Idle wondering .. not like I'm about to bid.

On Fri, 13 Apr 2012, Al Kossow wrote: Notice that the "gimme a disk" screen shows a 3.5-inch disk rather than a twiggy? I wonder what that means about how development went. -- David Griffith dgriffi at cs.csubak.edu A: Because it fouls the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?

On 4/13/2012 1:40 PM, Jules Richardson wrote: Sort of like the 45 caliber Luger. Made specifically to compete for the 1911 contract with the Army, and exceedingly rare because few left the hands of the US Army or Luger. You hear stories, and a few have popped up, but one never knows. Jim

Al Kossow wrote: Is it known whether that machine "works", for any value of "works"? Does CHM have any artifacts relating to the earlier 6809-based Mac prototypes? Those photos provide a fascinating glimpse into one stage of the early Mac development. * It predates the Twiggy drive, and uses a Disk II. Presumably the logic board does not have the drive speed PWM circuitry. Maybe it didn't have the type of sound support found in the production model either, since that was related to the drive speed PWM. * It uses fewer PALs than the production machine, which seems surprising since there don't appear to be too many "jelly bean" parts that could have been absorbed into the additional PALs. Probably the lack of drive speed PWM (and possibly sound) accounts for part of that. * It predates the IWM, and uses a discrete version of the Disk II controller, e.g., with the P6A PROM, LS174 state register, and LS323 data shift register for the state machine. It does not have the 9334/LS259 octal addressable latch used by the Disk II controller, and most likely uses port pins of the 6522 in place of that. It can't offer the "synchronous mode" of the IWM, which would have made it difficult if not impossible for a 68K device driver to support the higher data rate of the later Twiggy or Sony drives. If they wanted to have compatibility with Apple II and III disks, which obviously would have been a huge win during the software development, the controller circuitry must be modified to run at a divide by eight from the main oscillator instead of divide by seven, though it would still be off by 4.4%, making interchange marginal unless you also tweaked the drive motor speed. (The IWM offered choice of 8x for use in the Mac or 7x for use in the Apple II and Lisa.) * It predates the RTC chip, so it appears to have no RTC and hence no "Parameter RAM". * It has three EPROM sockets rather than two, and although the 28-pin sockets could accommodate larger capacity EPROMs, the chip is a 2732 (4K*8), which is obviously only large enough to have a boot loader and maybe a simple monitor or diagnostics. The real software had to be booted into the 128K of RAM. When this prototype was built, the plan for the software was probably much less ambitious than what eventually shipped. At the time, I think 2764 EPROMs (8K*8) weren't yet readily available. Masked ROMs were usually available at about double the density of EPROMs, so they might have had in mind to use three 16K*8 ROMs, for a total of 48KB of firmware. * It uses two 6551 ACIAs for the serial, rather than the 8530 SCC, so it wouldn't be able to support AppleTalk. * Despite using the 6551 ACIA rather than the 8530 SCC, it uses the 26LS30 and 26LS32 for level shifting for the serial ports, which seems like a very unusual choice. * The mouse connector is on the front rather than the back. This seems like a good idea; I wonder why it was changed. * The "Programmer's Switch" is on the back rather than the side. Possibly the vent holes at the bottom of the sides hadn't been planned yet. * The connection for the analog board is different. It looks like the 6-pin power connector is probably compatible with the Apple II power supply, and the other header (J8) is probably for the video signals, though it is surprising that it would need eight pins for that, unless it is actually supplying power to the analog board via that connector. * Like the production 128K Mac, it appears that all of the timing (except for the RTC, which isn't present) is derived from the single 15.6672 MHz crystal. Given that it is using the 6551 ACIA rather than the SCC, there has to be a 1.8432 MHz clock (or within a few %) for the baud rates to be correct. I'd never noticed it before, but the standard Mac clock frequency of 15.6672 is *exactly* eight times the 1.8432 MHz needed for the 6551 baud rate generator. That's not a coincidence. (The SCC in the production Mac can divide down from other frequencies, so it's not an issue there except at the highest serial rates.) In hindsight, the 15.6672 MHz figure must have been chosen as something that would divide exactly to get the desired serial rates, was within the desired range for the video dot clock, and could be divided down to suitable frequencies for the disk controller and 68000. * I wonder what the two pin header (jumper?) J6, between the 68K and the DRAM, was for?