Different Macintosh in Original User Guide?

[Gorgonops]

... Note of course that if the code version on these ROMs is significantly older than the latter half of '83 they may well not boot a shipped System version. The Toolbox ROM and the part of the OS that resides in RAM are very tightly interwoven and they were squashing bugs right up to the end.

That said, yes, it's totally worth trying to clean and lube the drives if you think you're up to it. Another possible worry is if these are pre-release mechanisms the driver in the ROM may not necessarily be compatible with later drives. As I recall there are actually compatibility issues with different revisions of the internal mechanisms in some shipped machines.

 

[Dog Cow]

OK - The torx arrived and - JACKPOT!  Both units have Mr. Macintosh inside on the video board, on the EPROM board, and on the Main Logic.  Here are the pix of both units.  

View attachment 28128

You do not have pre-release ROMs.

7.0 on the ROM labels means the final shipping version of the 64K Macintosh ROM. These ROMs will have no trouble booting the usual System startup disks once you get your floppy drive working.

 

[MOS8_030]

Neat-O old machines!

The 400K drives may be missing the felt pads or they may need replaced.  Yeah, give then a thorough cleaning and inspection.

 

[North Hedge Ned]

What is the best way to recondition the drives?  I fired on up last night - the one with weird video issue unfortunately, and I could hear the read/write heads adjust themselves back into the ready position.  However, insert disk and it is weird - it pushes in, and clicks down almost manually, but no read write sound.  To eject, there is nothing behind the paper clip hole.  However, just a gentle push and voila, the disk pops up and out again.  It's like the first Sony drives took the disk in manually by a push in and down, and the revers to eject.  Nothing powered about it - it seems - not like the production units I believe, which are power-mechanically insert and eject....

 

[unity]

Pics of the drives might be very interesting. I have had, and might still, some very early Sony drives that have some differences from the usually shipping units. Nothing crazy though. The drives were never power-insert, only elect. They just has a very nice mechanism that grabbed the disk and pulled it in "automatically" where as the much, much later "manual" insert drives needed more help from the user.

They way you describe things, the disk is not mounting in all the way because its gummed up. And if it does not seat right, the sensor to detect the floppy being there will not be triggered (its up front). Typically the disk ends up at an angle with the leading edge at the opening being higher up. It is why I will never, ever use lithium grease on drives. It dries up and hardens making it hell to remove but it can be done. I always service the drives with very light amounts of 3-in-one oil after cleaning. Very, very little is needed. These will not be daily use machines after all and the oil can easily be cleaned off even years later.

For the machine with display issues, I suggest you dont power it up anymore. It is likely a cold solder joint that needs a reflow. Very, very common issues. But these joints can create a lot of heat and melt connectors. I have plenty of examples of Macs that did operate seemingly fine, but the cold joints literally burned up and melted the connectors.

 

[MOS8_030]

Here's a good starting point for checking the floppy drives.



Also there are PDF copies of the Dead Mac Scrolls floating around on the web.

 

[Trash80toHP_Mini]

Interesting, I'd always assumed the wire to be a an open ground bus for additional discharge safety for ESD over numerous ROM swaps. In the closeups it appears to be a +5V patch needed  to drive the much higher chip count on the adapter board. Is it soldered to the resistor on the supply side/power plane? If not, what's the regulated output supply powering the ROM daughtercard?

SonyMacMan-NHN



TwiggyMac-AF



WAG: very curious, at rev. 7.1 it appears they may have been trying harder/longer to get Twiggy up and running than Sony at 7.0 or that it had gone through more iterations in the process and frozen at that level? Do the markings on the SonyROMs imply/indicate that ROM 1 Hi may have been frozen, ROM 0 Low might have been in the process of being actively debugged and the pair in between somewhere in between the two states and might be frozen at the 7.1 level after debugging was complete?

Great stuff, NHN!

 

[unity]

It is tapped into a capacitor, so yes probably a ground.

 

[Gorgonops]

It is tapped into a capacitor, so yes probably a ground.

Are we talking about that metal fence wrapped around the EPROM board and where it seems to connect to a point labeled "CR3"? A part labeled "CR" is usually a "Current Rectifier", IE, a diode, not a capacitor. (The board has plenty of axial bypass capacitors on it labeled as Cxx, the part at CR3 is physically different and looks like a diode to me.)

I can't find CR3 listed on any Mac logic board schematic (there is one on the analog board and it is a diode), googling up a picture of a shipping 128k motherboard I can see that portion of the board is a substantially different so that component may well not exist in the production version.

That said it probably is a ground. I'm going to hazard a guess that it's there to act like a fence to divert some electromagnetic interference they thought they might be getting from some other component, like the disk drive or monitor, and they added it in response to some unexplained glitchy-ness that showed up after adding the EPROM board. (Which is why it's made out of wire crudely lashed in place instead of connected to tracks on the PCB.)

 

[Gorgonops]

... I am a little curious about the use of four 27128s instead of just using a pair of 27256s inserted directly into the ROM sockets, but as this was 1983 it's possible that the 27256 either didn't quite exist yet or was very expensive. EPROM capacity generally lagged mask ROMs and 32k was a pretty decently large ROM at the time. (Also, according to Folklore they were *really* trying to keep the ROM to 32k until pretty late in the process, so maybe they simply had a ton of 27128s lying around to reuse.)

 

[unity]

Yes, the wire. I assume that is what we are talking about.  And you are right, that is a diode. I did not look at the identifier, looked like a glass capacitor so common on these.  CR3 is on a 128k board but in location B12.

 

[North Hedge Ned]

MOS8-030 - thanks for the link to the cleaning.  Very useful and will put it into practice this weekend.  I found an old floppy that someone had handwritten on it "System Disk 400K".  So, will see if I can bring life into the working one.  

Unity - thanks for the feedback and the input, especially on the non-working display.  So, cold solder joints.... easy fix?  or is this one a nice non-functioning display piece? ... Prototype fish tank?  Have on display in exploded view?  I did notice one strange thing with this one...  The hardware around the base of the yoke is very different than the working one.  The working one has a white ring around it with little magnets place at various locations.  The non-working one has only magnets seemingly taped on (Clear yellow orange tape) magnets.  Also, different labels etc.  The working one (didn't take a pic... yet) was a Samsung I think.  Attached, here is a photo of the non-working unit.

Thanks to all for your continued discussion around these units - certainly the mystery unfolds, and the information collection is awesome!

 

[North Hedge Ned]

The non-working CRT

 

[North Hedge Ned]

Hi everyone - Great News!  One of my two 128K Prototypes LIVES!  I pulled the floppy out and gave it a lube up.  Works like a charm.  Found an old disk kicking around with "System Software 400K" written on it.  Turns out to be System 1.1, Finder 1.1g.  Anyhow, the unit is alive and well.  If all goes well, there should be some photos with this post.  With the floppy removed, you can clearly see in the metal an opening large enough for a Twiggy Drive, and the floppy carrier for the Sony plugs that hole up.  Now to figure out if I can fix the other one with the odd bright horizontal lines in the middle of the screen.  Thank for your continued input everyone.

 

[North Hedge Ned]

For some reason image uploading is not working

 

[unity]

Very nice! Good to hear!

 

[North Hedge Ned]

There we go - the originals are too big I guess. Funny how my iPhone makes the screen look blue.  It's really b&w - for real.

 

[Gorgonops]

With the floppy removed, you can clearly see in the metal an opening large enough for a Twiggy Drive, and the floppy carrier for the Sony plugs that hole up.

This is the case for all of the original Macs through the Plus, although it does look like the drive mount in yours might be a less refined version of the metal stampings in later models. It doesn't prove that your machine originally had a Twiggy drive at any point. But your motherboard and other parts at least overlap with Twiggy models, so... yeah. Congratulations on getting it going!

I wonder how long machines like this were kicking around Apple HQ and in the hands of early developers before the survivors all ended up in the closet. (Possibly quite a while given they're apparently able to run the shipped software versions.) It'd be a laugh to run across one that had been modified for 512k RAM.

 

[PB145B]

Outstanding! So nice to see a prototype machine alive and well!

I gotta say, I am indeed a little jealous  

 

[unity]

Nice pics. Even that Sony drive is probably a proto. Do you have a shot of the front? I have a couple very early ones where the copper heat sink is different. Wondering if yours looks the same.