Mystical Macintosh SE connector on the back

[8bitbubsy]

I'm getting a Macintosh SE soon, and it has this connector on the back that I haven't seen before.
Does anyone recognize this kind of Macintosh SE add-on? It could be anything of course, even a custom hack. I can't seem to find anything like this on google.

https://imgur.com/fhKkiw2

 

[cheesestraws]

Probably monochrome TTL video? That's reasonably often on a 9-pin D-sub

 

[8bitbubsy]

Yeah I was thinking some simple video output as well, but was wondering if anyone recognize this by the position of the connector, the white color of the connector, and so on.

 

[Berenod]

Bit weird, for video I would rather expect a female db9...
Then again, no standards whatsoever back then.
You'd often see a videocard with a connector, which would only work with a monitor from the same brand!

Guess you'll have to peek inside once you have the machine!

In the link below you'll see a videocard in one of my SE's, not yet found the time to check what exact signal it puts out...

Unknown Mac SE PDS card

Cleaning up a Mac SE for a friend (Miniscribe didn't work anymore), got it back to work perfectly nice. But, when I got it, I noticed an extra DB 9 connector on the back, never seen one before. After opening the machine up, the DB9 connector was patched up to a PDS card installed in the...

68kmla.org

 

[8bitbubsy]

Oh, it was "just" a 68030 25MHz accelerator.

 

[joshc]

Lucky! Ready for an FPU as well.

 

[8bitbubsy]

Yup! I even have one that I will install. Also, that one oscillator on the board was bent out of its socket, will fix that.
I opened up the machine first to inspect it before turning it on. Will desolder that battery and install one of those classic PRAM battery holders, and install a new battery too.

EDIT: Wow, is that L2 cache ZIP RAM I see? Could also be normal RAM, not sure.
EDIT2: Ah, it's VRAM, so that mystical connector is indeed a video connector.

 

[Phipli]

Oh, it was "just" a 68030 25MHz accelerator.

Its either a mobius, total systems or an Applied Engineering board. They all made basically the same board.

The GemStart drivers should work.

 

[8bitbubsy]

It's a Mobius 030, according to the control panel software at least.
How much is this accelerator worth? I don't think I want to keep it, as I want the Mac SE to be compatible with all the good old software and games out there.

 

[Phipli]

It's a Mobius 030, according to the control panel software at least.
How much is this accelerator worth? I don't think I want to keep it, as I want the Mac SE to be compatible with all the good old software and games out there.

The upgrade doesn't reduce compatibility with old games, and likely can be disabled easily (I have the manual somewhere I think, but suspect that holding down the programmer's interrupt button while powering on disables it.

I have the same card and have never had a program refuse to run because of it. They're hard to find and make your SE faster than an SE/30. Possibly even allowing you to put in more than the maximum 4MB of RAM - I forget if that card supports it. I'd really strongly suggest keeping it! Its an awesome thing to have!

 

[Phipli]

Here is mine, ignore the CPU / FPU markings, I swapped chips between boards. I believe mine was also sold as a Mobius.

Could you let me know what version your control panel is? In case it is one that hasn't been preserved (don't format the disk until it and any extensions are backed up!).

 

[8bitbubsy]

but suspect that holding down the programmer's interrupt button while powering on disables it.

If only I had the side buttons on my Macintosh SE. The plastic part that clips on is missing!

I had version 4.99 of the Mobious 030 control panel, but now the 40MB SCSI HDD is completely dead, so I couldn't preserve it in time...

 

[Phipli]

And here is a benchmark of my card, highlighted in yellow, fitted with an FPU running at 20MHz (so 25MHz CPU and 20MHz FPU). I think I was running another firm's drivers, so there might be small differences in the performance you get.

Driver and manuals attached, if I grabbed the right ones.

If only I had the side buttons on my Macintosh SE. The plastic part that clips on is missing!

I haven't needed to disable mine a single time. And the most common solution is to turn off the cache in the control panel.

 

[Phipli]

Going to have to 3D print yourself some buttons

 

[8bitbubsy]

Thanks. One thing I noticed btw, is that if I installed an FPU (and set the FPU jumper to 25MHz), the machine would freeze when loading the Mobius 030 extension on boot. I tried two different FPUs, and one that I know for sure is 100% genuine.

 

[Phipli]

Thanks. One thing I noticed btw, is that if I installed an FPU (and set the FPU jumper to 25MHz), the machine would freeze when loading the Mobius 030 extension on boot. I tried two different FPUs, and one that I know for sure is 100% genuine.

Curious. Do you have a clock to put in the socket U42? I think that is the only way I have run mine. It didn't come with an FPU.

Make sure you put it in the right way!

 

[Phipli]

See the serial numbers? I wonder was yours the 4th of this variant they made? Its common to start from a high number, and mine is newer (91 vs 90) and 50328, vs 50004...

Edit - your FPGA is date coded Aug 1990, mine is March 1991, so about 6 months difference between those parts.

 

[8bitbubsy]

It may be an old board, yeah.

Anyway, about the FPU. The 25MHz jumper position is supposed to use the same 25MHz clock as the CPU, so that no extra oscillator is needed. I don't have any 25MHz oscillator to tests with. I saw images of this board with a 25MHz FPU with no FPU crystal.

 

[Phipli]

Anyway, about the FPU. The 25MHz jumper position is supposed to use the same 25MHz clock as the CPU, so that no extra oscillator is needed. I don't have any 25MHz oscillator to tests with. I saw images of this board with a 25MHz FPU with no FPU crystal.

Yes I understand, I am running mine at 20MHz with an extra crystal because I didn't have a spare 25MHz FPU. I was suggesting it to make the setup the same as mine as a simple diagnostics step (mine works like that, perhaps the labelling is bad on the settings header, or there is a fault on the board. Also high speed clocks don't like travelling long distances on boards, so using the optional clock might help).

You could put any speed clock in there as long as it was within the capabilities of the FPU. They run asynchronously to the processor. If I had one I'd have a 50MHz 68882 in there with a 50MHz clock and "20" selected.

 

[8bitbubsy]

Update: The PSU measures 7.7v on the 12v rail, so I think that's possibly why the HDD "stopped" working.
EDIT: My bad, I didn't make good enough contact with the pins while measuring. It's 12.7v.

5v is spot on, though.

I'll get the whole system (motherboard, analog board and PSU) recapped at some point.