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I am designing a SBC that will feature the Motorola 68000 (or one of its descendants) but am having trouble finding new chips. The only chips that I have been able to find on Mouser or Digi-Key are the MC68SEC000AA10 and MC68SEC000AA16, both of which are NRND.

My questions are as follows:
1. Is there a modern (and non NRND) replacement for the MC68000? If so, what is it. 2. Should I (as a hobbyist) even worry about NRND/EOL parts for a system that I will build (at most) a handful of?

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  • \$\begingroup\$ To clarify, the replacement must be a MPU (not MCU) and must have the same ISA as the 68k. \$\endgroup\$ May 4, 2016 at 4:39
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    \$\begingroup\$ You've also overlooked the 68332 -- it's kind of a halfway house between a MPU and a MCU, and uses a 68k core, but is also NRND. \$\endgroup\$ May 6, 2016 at 0:07
  • \$\begingroup\$ Thanks for the suggestion. I think that I am going to stick with a "pure" MPU as I want to design everything except the MPU myself (as this is a purely academic pursuit). \$\endgroup\$ May 6, 2016 at 1:56

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The natural successor of the 68000 range of CPUs are the ColdFire microcontrollers designed for embedded platforms. They have sort of the same ISA, but some instructions are removed and some have been added. This means that they are mostly binary compatible, at least in user mode, but some instructions have to be trapped and emulated if you want to run completely unmodified 68000-code. The removed instructions are notably a lot of the byte/word addressing modes, meaning that it is more focused on 32-bit applications. They also have some very nice new instructions, for example the EMAC unit for doing DSP operations.

It is unclear to me what you mean to be the difference between an MPU and an MCU. I assume you mean that you want to attach external RAM, which is certainly possible with a lot of the ColdFire MPUs and MCUs. There are too many devices to list here, and you haven't given much to filter on, so you just have to search for a device that suits your needs.

If you're just building a handful, I don't see why you should worry about ICs which are marked end-of-life.

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  • \$\begingroup\$ By MPU I meant a system that did not have integrated RAM, ROM, or interface controllers (like the original 68k or 6502). \$\endgroup\$ May 4, 2016 at 5:48
  • \$\begingroup\$ I will look into ColdFire but as you have pointed out, I should have no issues with NRND/EOL components if I am only making a few boards. \$\endgroup\$ May 4, 2016 at 5:49
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If you really want the 68K in a modern part, there are soft cores for your FPGA of choice.

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