Sun Solaris 1.x
Solaris is a Unix based operating system created by Sun Microsystems (now purchased by Oracle in 2010). It is the successor to SunOS and was released initially in June of 1992. The OS is based off of System V Unix and its first release was known internally as SunOS 5. This OS was typically used on SPARC based processors, up until 1994 when it began to support x86 and x86-64 based machines. Versions of Solaris up until version 8 are considered abandoned, with version 9's support ending in October 2014.

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https://github.com/phabrics/nme
qemu-system-sparc -M SS-5 -m 64 -cdrom Solaris_1.1.2.img -boot d -nographic -smp 1
You can create image with and use -hda sparc_disk.qcow2 to mount it.
qemu-img create -f qcow2 sparc_disk.qcow2 1G
use 'format' in installation to partition and create a filesystem.
Unfortunately Sun install CDs have partitions and installation fails since it cant access other partition. I tried something like
qemu-system-sparc -M SS-5 -m 64 -nographic -hda sparc_disk.qcow2 -smp 1 -drive file=Solaris_1.1.2.img,format=raw,media=cdrom,readonly=on -boot d
But didn't manage to make it work.