NetBSD
A member of the open source family of Berkeley Software Distribution (BSD) UNIX-like operating systems, along with FreeBSD and OpenBSD, NetBSD is available for a wide range of hardware platforms (Platforms supported by NetBSD), including support for many systems of historical interest.
QEMU and SPARC
The user-space and system emulator QEMU provides emulation of a number of 32-bit SPARC systems. The emulated Sun Microsystems machines are Mbus based 'sun4m' systems, which are widely supported by many operating systems. The first of the 'sun4m' systems, the SPARCserver 600MP series, was launched in 1991, with smaller servers and workstations following. The last of the 'sun4m' line left regular support from Sun back in 2000, but support remained in Solaris 9, which left support in 2014. As such these systems were in common use for well over a decade, and were sufficiently common to be used in control systems as well as in server rooms and as desktops.
The default 32-bit SPARC system emulated in QEMU is the Sun Microsystems SPARCstation 5 (Wikipedia), which is a mid-range UNIX workstation of the mid-1990s. The emulation provides:
- CPU: microSPARC II
- RAM: default 128 MiB, max. 256 MiB
- Disk controller: SCSI Sun esp
- Network controller: Sun LANCE ethernet (le)
- Graphics: Sun tcx
For its time these specs are quite respectable, and the server emulations provide alternatives supporting more memory (up to 1,856 MiB in my tests) and additional processors. Since the emulation isn't subject the the limitations of the actual hardware and its connections, processor, disk and network performance often exceed that of the originals.
Note: it is easier to install NetBSD/sparc on QEMU when using the OpenBIOS firmware (QEMU default) than when using Sun's OpenBoot. This suggests that there may be some specific support in NetBSD and QEMU for this configuration.