Prototype Mac 512k motherboard yellow paint?

[KenB123]

Today I recieved a motherboard that has some very interesting characteristics. Something I have never seen before leading me to believe it's a late prototype. As you can see form the pictures it has yellow paint instead of the normal white paint marking what chips go where and what component is what.

Another interesting thing I not is it has these weird circle markers in 2 of the corners.

It also has a hand written number on the serial number.

Also I've never seen this kind of branded ram chips in a 512k

When I got this motherboard the rom chips were removed so I just threw in a pair of rom chips

When I tried to boot it it came up an error most likely a ram error;(

Also today I rec a late model 128k motherboard I would call it the second revision motherboard the kind that you would get out of a 128 that has the Macintosh 128k label on the back of it.

Anyway that motherboard has some very interesting set of rom chips in them

Surprisingly the 128k motherboard even with the know low quality doomed to fail Apple branded ram chips booted up just fine! I was happy to see that.

If anyone has any idea what this 512k motherboard could be or if it's just a normal nothing special board or just want to talk about it feel free to leave a post and maybe we can figure this out

Thank you everyone!!!

 

[Macdrone]

Not sure about the roms but I have a 512 in yellow and one in white.

Most likely where it was built is the reason for color.

 

[unity]

Like so?

https://68kmla.org/forums/index.php?/topic/23984-128512k-yellow-silk-screened-motherboard/

I have one. Check the board part number, see if it end in "F". If its an F like mine, I still think they were a low volume run of some original "hybrid" variant. They were often referenced in material, but not seen too often in the wild. In fact, to my knowledge, I am the first to put pics online even. Sorta like the very first run of SE/30 boards - but the SE/30 boards are seen in the wild.

 

[KenB123]

Thanks for the link that exains a lot!!!

It appears I also have the f at the end of the serial

I think I put 2 and 2 together and possibly figured this out. These came in a box labeled Bill Fernandez. If you don't kn who he is a quick Google sear will explain who he is. I believe these were sent before the 512 was released to developers possibly.

I might have to get this board framed because of how cool it looks especially because it doesn't work which stinks

Thanks for helping identify what this is!!!

If anyone has any ideas what to do with it or wants it let me know!

I have a bunch of 128 and 512 boards that are not working and are beyond my knowledge to repair them. If anyone wants them let me know.

Thanks everyone who helped identify what this most likely is!!!

 

[KenB123]

Here's the serial.

 

[unity]

Yup, an F board. Again, can not say for sure my theory is 100% but it would make sense they are engineering samples of some sort. What change was made to the common variant I do not know.

 

[Compgeke]

Your sadmac code is indicating a RAM failure, specifically F6 if I'm decoding the 100 right.

It's most likely fixable and if these are anything like old PCs and Commodores and such you can piggyback a known good chip of the same size\speed and test with that, just make sure not to short any pins to eachother.

 

[KenB123]

Oh really? I didn't know you could do that! Thanks for the advice!