Motorola 68000 series
Introduced in 1979 the Motorola 68000 series was used in a wide range of computers through the 1980s and 1990s. Initially using a 32-bit instruction set and 32-bit registers combined with a 16-bit data bus, which Motorola dubbed a 16/32-bit processor, later iterations would implement fully 32-bit architectures, while remaining instruction compatible. The initial models provided 8-bit (68008) and 16-bit (68000, 68010) options for the external data bus allowing the use of cheaper support chips in markets that were typically 8-bit and 16-bit dominated in the early 1980s. The first fully 32-bit model, the 68020 introduced in 1984 (a year before Intel launched the 80386), initially appeared in UNIX workstations and its successors would be at the core of home computers in the 1990s. While 68000 series processors no longer appear in desktop systems, they can still be found in embedded applications.
Linux and Motorola 68000 series
Unsurprisingly the Motorola 68000 series was one of the first systems to have a Linux port (see Linux/m68k: Linux on Motorola's 68000 Processor | Linux Journal). Arguably Linux/m68k was the first port of Linux to a non-x86 architecture, initially starting off as a parallel fork of the Linux kernel, and later being incorporated into the mainline kernel, once work to support multiple platforms was in place (see Linus Torvalds 1997 M.Sc. thesis "Linux: a Portable Operating System").
A wide range of Motorola 68000 series systems are supported. Although a memory management unit (MMU) is required for support, which excludes some system variants using processors which didn't include the MMU or where the MMU is non-functional (systems without an MMU may be supported by μClinux (Wikipedia)). Looking around for a Linux distribution with Motorola 68000 series support and which doesn't require too much setup, it looks like Debian is the best bet.
Debian Linux had official release support in Debian 2.0 (Hamm) through Debian 3.1 (Sarge), and has continued to support the architecture through Debian - Ports. Currently a unofficial Linux/m68k network installation image is available for Debian 10 (buster) (https://cdimage.debian.org/cdimage/ports/10.0/m68k/iso-cd/). That sounds good, so let's give it a go...
QEMU
The wide range of systems that used the Motorola 68000 series means there are a lot of emulation options... Since we've looked at QEMU in previous emulation posts, let's see what QEMU offers for these systems...
QEMU has a relatively limited selection of system emulations for the Motorola 68000 series:
| Arnewsh Inc. SBC5206 | an5206 | evaluation board |
|---|---|---|
| NXP MCF5208 Evaluation Board | mcf5208evb | evaluation board |
| NeXT NeXTcube (Wikipedia) | next-cube | UNIX workstation |
| Apple Macintosh Quadra 800 (Wikipedia) | q800 | desktop system |
Note: with QEMU 6.0 support has been added for a virt machine that is more flexible than systems considered here (see QEMU M680x0 support [PDF]).
The QEMU wiki has a description of how to install Linux on the q800 system (Documentation/Platforms/m68k - QEMU), so that sounds like a good place to begin...
Checking Apple Support, EveryMac.com, Wikipedia the hardware specification for the 'q800' would be:
| System | Apple Macintosh Quadra 800 |
|---|---|
| CPU | 68040 @ 33 MHz, includes PMMU & FPU |
| RAM | 8 MiB (136 MiB max.) |
| Floppy | 3.5" 1.44MB |
| Storage | Emulex SCSI Processor (ESP236) controller |
| SCSI internal hard disk 230 MB or 500 MB | |
| SCSI 2x CD-ROM drive | |
| Video | framebuffer, 512 KiB or 1.0 MiB |
| Network | SONIC (DP83932) 10Mb/s ethernet AAUI-15 |
| Keyboard & Mouse | ADB |
Third-party processor clock upgrades could get the 68040 to 40 MHz or 50 MHz, and there was a PowerPC 601 @ 100 MHz upgrade processor option.
Since QEMU is not limited by the physical hardware, there is the option of having more memory than the system could support. For 'q800' it turns out that the maximum RAM is around 1,000 MiB (with 1.0 GiB problems appear).