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The little PLCC chip (U22) next to the crystal is a custom clock chip that multiplys the output of the crystal up the 50Mhz (which is then devided by 2 by the VLSI to get the 25MHZ CPU clock). The placement of the resistor signals to the clock chip and VLSI what speed the system should be...

Did a little bit more testing today, got the board to 7.1 from a scsi drive (after doing a little bit of shuffling around to get the correct system enabler on the HDD) :) I also tried swapping the main oscillator crystal from a more commonly available 32Mhz crystal (The original being...

Annnd, We have floppy(icon)! :) All the grief was caused by this: That was causing a short between RA1 and RA2. Annoyingly because of the way sprint works this dose not show up as a error when you run DRC..... Audio still dosen't sound correct and is very quiet so it looks like there is a...

A progress update: The board has now been populated enough for testing, and after finding and removing a short between /BERR and /HALT on the CPU the board now produces a slightly garbled chimes of death when powered on. This is good as if the board is working enough to produce a chime it must...

They do, I have one around here somewhere It'll probably be quite difficult to source one now, given they would have been pretty niche even back in the day and 2.5" scsi drives are all but extinct now It wouldn't be too difficult to reproduce though given it's just a straight through passive...

And V1.1 PCB's are here!

Boards are here, and in JLCPCB's new and rather fetching purple! Soldering the PLCC's and SOJ's: I did start trying to solder them by hand, but quickly remembered why I hate soldering PLCC's by hand and quickly went back to using a stencil and solder paste. It's just so much easier! And...

Should be all that's needed, I need to build one up to see if I made any other mistakes. I'm just annoyed as that was the fault that was stopping the V1.0's booting and I somehow forgot to fix it...

Awesome! I can finally get more than 8mb in my IIx. I should have everything needed in stock too, just have to add some of these PCB's to my next order with JLC :)

This is a ongoing project to create a 1:1 replica of the original Macintosh LC Logicboard This project is in a fairly advanced state now, The board has been drawn up and V1.0 boots with a few patches and one trace cut: This board has been fully tested and everything on it works, Not bad for a...

This is a ongoing project to create 1:1 replica's of the Macintosh LC III Logicboard Most of the hard work has hopefully been done on this one, a V1.0 PCB has been drawn up and sent off for manufacture: I'm currently awaiting the boards from china, should be here by mid next week More updates...