#jlcpcb

Flexible circuit boards manufacturing (JLCPCB, 2023)

A lot of firsts in this project — my first time using assembly service, the largest PCB I've ever ordered, the longest BOM, the most complex schematic ... Basically, it is the culmination of many years of work all brought together.

But speaking of firsts ...

New Boards Day!

They're here!

This is a project that has been a long time coming, and something I have wanted to do for a long time.

This is the largest, most complex PCB I have ever designed — a 9.6x9.6 inch (244x244mm) square, 4-layer, complete motherboard for my MC68030 homebrew computer project.

It is designed to support the Motorola MC68030 CPU, MC68882 FPU, two 72-pin SIMM sockets, 512kB ROM, two serial ports, one parallel port, PS/2 keyboard, 4-bpp VGA video, IDE hard drive, and three ISA expansion slots. A complete system all in a microATX form factor.

This builds on my previous work with the 68030, based heavily on my wire-wrap project and the boards that followed. It's a project over four years in the making. I have made a few improvements on the old design, like 16550-compatible serial ports and an updated memory map to support much more RAM in a contiguous space.

Keeping with my existing system designs, I've combined most of the logic into a set of CPLDs. This makes things like PCB layout and logic debugging so much easier. Most of the remaining discrete logic on the board is 74'245 bus transceivers for driving memory and the ISA slots.

I've kept the name "wrap030" in honor of the project's origin as a wire-wrapped prototype, despite the move to proper PCBs. It's just what I've been calling the project in my own head (and design files) all this time, so at this point no other name would feel right.

I of course wasted no time starting to assemble one, but I did stop myself from getting too carried away with the soldering iron. I want to be methodical and test each section before moving on to the next.

I have already found one major error in my board layout — the footprint for the VGA connector is backwards. I may need to bodge together some kind of adapter.

So far I've confirmed the minimalist AT power supply section works with no major shorts on power supply rails, and the reset circuit is working as expected. Next step is to try a free run test with the CPU to ensure the system clock and CPU are working. Once that is confirmed working, I can start loading logic for accessing ROM. My goal is to have it at least running BASIC on a serial terminal by VCFSW in June.

I've forked my existing wrap030 repository on GitHub for this new Wrap030-ATX, since it does make some breaking changes that will require updates to logic and programs. New repo is here:

I ordered some new PCBs for my 68030 project.

New Boards Day

I ordered some custom breakout boards from JLCPCB.

QFP-208

QFP-160

PC-AT & PC-ATX power supply headers

5V PCI

PS/2 & PC-AT keyboard

72-pin SIMM