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What techniques are there to "prototype" a component like a MC68020 processor? Since the pins are in a 13x13 geometry standard bread boards will not do. Are there something like bread boards for this type of application? Should I go with wire wrapping the MC and connect it to a components on breadboards using wires and band cables?

New to this, I have quite some experience in OS development as well as low level programming and compiler design. Not as much in hardware design. I thought I sink my teeth into a fully fledged nerd project with an old MC68020 from eBay and make it a really long-time project, taking my time.

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    \$\begingroup\$ Design a "carrier" PCB with a ZIF socket and the RAM, PSU, crystal and decoupling capacitors. \$\endgroup\$
    – pjc50
    Jul 4, 2017 at 15:32
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    \$\begingroup\$ I first thought of designing the "carrier PCB" for the processor alone. I then thought I'd need to add the crystal(s), but then I also needed the clock-signal-ICs (of course), then RAM... etc etc. This would end up being some sort of a developer board for the MC68020, right? Are there not any such PCBs around already? \$\endgroup\$
    – Mats
    Jul 4, 2017 at 15:40
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    \$\begingroup\$ searching for MC68020 dev board brings up .. someone's graduate thesis from Turkey in 1989, so probably not. dtic.mil/dtic/tr/fulltext/u2/a223984.pdf \$\endgroup\$
    – pjc50
    Jul 4, 2017 at 19:23
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    \$\begingroup\$ Ah yes! Good old 68020. When failure in your satellite/missile/jet fighter/nuclear power plant control system isn't an option. \$\endgroup\$
    – winny
    Jul 5, 2017 at 7:42

2 Answers 2

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The device looks like this: -

enter image description here

With pins on a 0.1" pitch so just get hold of some female headers that can be stacked and solder wires to the female pin headers.

Be aware that you will get some unusual results due to weakened power supply decoupling and lack of ground plane that can only be solved with a proper PCB tailored for the MC68020 processor.

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    \$\begingroup\$ I would be surprised if it worked at full speed with this setup - "unusual results" is understating it somewhat. \$\endgroup\$
    – pjc50
    Jul 4, 2017 at 15:31
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    \$\begingroup\$ Yes, that looks fairly familiar :) I know the IC package is PGA-169. Is that weakened power issue sounds worrying "something to consider" or a reason to rethink the project? Would it be hard to get a "decoupled" system to actually work? \$\endgroup\$
    – Mats
    Jul 4, 2017 at 15:31
  • \$\begingroup\$ I found this one and a follow-up on YouTube: youtube.com/watch?v=j8VcJ2l2N2M \$\endgroup\$
    – Mats
    Jul 10, 2017 at 20:24
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The easiest solution for a software developer is to get an evaluation board for the specific CPU. Sadly, for the MC680xx series, these boards are quite expensive.

For low level debugging of such CPU, you will need an ICE (In-circuit emulator), as the MC68020 doesn't have JTAG capability.

For a pure hardware debugging, there are wire wrap PGA sockets available, so it is possible (not easy) to build a prototype using wire wrap technique.

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  • \$\begingroup\$ Yes that would be easy :) I would like to build something hard. I have built quite a few hoppy applications as well as my own Arduino from scratch and I now want to up my game. Would the MC68020 lack of JTAG support make that a bad center piece of the project? Would you suggest another processor? \$\endgroup\$
    – Mats
    Jul 4, 2017 at 15:33
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    \$\begingroup\$ Do you have tens of thousands of USD for an ICE? Any modern device will have JTAG, and evaluation boards, which can start at less than 10$. The choice of CPU is up to you and really depends on your requirements. \$\endgroup\$
    – Lior Bilia
    Jul 4, 2017 at 15:57
  • \$\begingroup\$ Nope, not tens of thousands :) What CPUs would you recommend? \$\endgroup\$
    – Mats
    Jul 4, 2017 at 16:22
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    \$\begingroup\$ Literally any modern microcontroller would be more suitable; if you prefer 68k there is Coldfire electronics.stackexchange.com/questions/232190/… \$\endgroup\$
    – pjc50
    Jul 4, 2017 at 19:25
  • \$\begingroup\$ I'm going to go with one of the ColdFires and thanks for the Turkish/Californian paper :) \$\endgroup\$
    – Mats
    Jul 10, 2017 at 20:21

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