Original Hackintoshy Thing

[YMAC]

Who remembers or has info on this mod? I have forgotten the details, it was a company in the early 90s called ATS (Atlanta Technical Specialists) that made a custom enclosure for Mac 128K/512K boards that converted it to external video. The external connector is a 9 pin and I cannot remember if it is a standard EGA or if the display was modified also. There was a book that talked about these systems, but I cannot remember what it was called and I cannot find it.

 

[Gorgonops]

Bookwise I think the title was something like "Build your own Macintosh and save a bundle".

The 9 pin output is probably intended for a TTL monochrome monitor like used on a PC MDA/Hercules card. Technically Mac video is pretty far out of band for those monitors (21khz vs. 18khz line rate) but at least some can tolerate it with some adjustments.

 

[Trash80toHP_Mini]

Are you saying you have that adapter in your possession or are only posting pictures of it? If the former, developing a schematic from it would be a wonderful recovery of lost information for posting online.

For that book and others: https://vintageapple.org/macbooks/

 

[YMAC]

I do have it, the board I have was one of the early hand made prototypes. Later on there were actual production boards made. I can work on a schematic and document it before it leaves my possession (been hauling this thing around for too long). Here are some more pics, thanks for the book name, that was the one. Now I just have to find a TTL monitor...

 

[Trash80toHP_Mini]

IIRC, @Gorgonops or @trag knows how TTL output can be converted to VGA. That would be the kicker. The Cat Mac articles in Computer Shopper were fascinating, that was the code name for such shenanigans before Hacintosh became the word of the day.

Very cool machine, that's a real piece of Hacker history. More pics of the wire harness please!

 

[Gorgonops]

If the machine still works I'd highly recommend putting some foil tape over the windows on the EPROMs. UV light will erase them over time.

I'm curious exactly what's going on with that floppy drive. Can you get some good pictures and otherwise document that setup?

 

[johnklos]

http://www.maccaps.com/MacCaps/Repair_books_files/Macintosh Repair and Upgrade Secrets.pdf

Page 168 and on describe the adapter. It's just a 74LS14, which is just an inverter with a Schmitt trigger, which just cleans up the signal so superfluous changes aren't reflected on the output.

The board in the first picture has a 74F253, which may be used to decode address bits or something like that for... a hard drive LED? It'd seem strange to have so much circuitry for just that, but I don't see any other hardware in there that would make use of this...

 

[YMAC]

Here are some detailed shots of the floppy. Super busy right now, I will follow up with more as time allows. I wish I could remember more, but I think it is a standard floppy.

 

[Gorgonops]

Interesting. Googling the model number of that drive indicates that it is a factory-built Fujitsu clone of an Apple drive. Didn't know such an animal existed.

 

[Franklinstein]

That floppy drive is certainly interesting. Fujitsu never built GCR floppy drives for Apple. Maybe they were intended to be used in 3rd party external units, of which I have seen a few examples using non-Sony drives. Epson made some, too, for sure used by Outbound in their Notebook clone series. 

If you don’t already have a buyer lined up for your ATS hack-a-Mac, consider dropping a post in the Trading Post. I’d be interested, for sure. 

 

[BadGoldEagle]

IIRC, @Gorgonops or @trag knows how TTL output can be converted to VGA.

The 9 pin output is probably intended for a TTL monochrome monitor like used on a PC MDA/Hercules card. Technically Mac video is pretty far out of band for those monitors (21khz vs. 18khz line rate) but at least some can tolerate it with some adjustments.

I wonder if one of those cheap arcade 'CRT' adapters can be tweaked to support the Mac's built in video... I have an external adapter that uses the same connector/interface and it'd be neat to have my Mac Plus' screen projected on the wall or something... The adapter itself seems easily reverse-engineerable.
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Oh and BTW, nice find!

 

[pcamen]

@BadGoldEagle That adapter you posted above looks very similar to the PowerR Presenter adapter I have for the SE or SE/30.





Yours, like mine (and the cat Mac above), has the DE-9 video connector.  I think this is just called RGB video.  I do see an RGB video to VGA cable on Amazon.com.  The PowerR instructions claim it works with the Sharp QA-50 or QA-75 LCD projection panel.  I found an article on the QA-50 in an old InfoWorld issue that says it supports MCGA and VGA, so perhaps simply converting RGB video to VGA is how these are supposed to be used.  

 

[BadGoldEagle]

As long as the RGB to VGA board supports the Mac's scan rate, it will work. However I haven't found any that say they support that mode.

 

[360alaska]

I bought one of these to try just that but I never got around to it:

 

[Gorgonops]

Yours, like mine (and the cat Mac above), has the DE-9 video connector.  I think this is just called RGB video.  I do see an RGB video to VGA cable on Amazon.com.  The PowerR instructions claim it works with the Sharp QA-50 or QA-75 LCD projection panel.  I found an article on the QA-50 in an old InfoWorld issue that says it supports MCGA and VGA, so perhaps simply converting RGB video to VGA is how these are supposed to be used.  

Be aware that there's a remote but non-zero chance that you'll damage a VGA monitor by using that cable to directly connect to an output like this. This port has digital TTL-level outputs, which means the high level is somewhere between 2.4v and 5v, while VGA analog is spec-ed as a swing between 0v and 0.7v. The input circuitry on a decently built monitor will *probably* tolerate the over-voltage but your mileage could definitely vary.

For the record, the info slip included with the PowerR adapter is referring to *digital* RGB monitors, like early NEC Multisyncs.