Solaris 2.0 only ran on desktop SPARCstations and a few other Sun machines.
Solaris 2.1 and 2.4 and later come in two flavors, SPARC and "x86".
Solaris 2.1 (and 2.2, ...) for SPARC run on all SPARCstations and clones, as well as all models of the Sun-4 family. The old FPU on the 4/110 and 4/2x0 is not supported, so floating point will be SLOW, but it does work.
Starting with 2.5 support for machines with kernel architecture "sun4" is dropped. I.e., the machines on which "uname -m" and "arch -k" return "sun4"; not the machines on which those commands return sun4c, sun4m, sun4u or sun4d. The unsupported machine include the sun4/110 (not to be confused with the SS4 @110MHz), sun4/2xx, sun4/3xx and sun4/4xx. These are all VME based deskside/server configurations.
All version of the SPARC PROMs should work under Solaris 2.x, but you can run into the following problems:
1) No part of the boot partition may be offset more than 1 GB
into the disk, unless you have a PROM with rev 2.6 or better.
Note that the number behind the point is not a fraction, it's
an integer. Hence 3.0 > 2.25 > 2.10 > 2.9 > 2.1 > 2.0 > 1.6.
2) If booting diskless, you need a link in the /tftpboot
directory, "tftpboot -> .". Admintool will make that
link automatically.
A Solaris port for the PowerPC has been completed, and has been released, effective Solaris 2.5.1.
Solaris 2.1, 2.4 and above for x86 have been released to end users. It runs on a wide range of high-end PC-architecture machines. "High-end" means: 16MB of RAM and an 80486 (or 33MHz or faster 80386DX). It will not run on your 4 MB 16MHz 386SX, so don't bother trying! Also, floating point hardware (80387-style) is absolutely required in 2.1. Starting with Solaris 2.4 for x86, a fp CO-processor is no-longer required, though still recommended. All three buses are supported: ISA, EISA, MCA. Some PCI devices are supported, though full bus nexus support for PCI is not there. See also 3.36.
To summarize all this, Jim Prescott gave this chart, which I've updated:
Solaris SunOS OpenWin Comments
1.0 4.1.1B 2.0
4.1.1_U1 2.0 sun3 EOL release (not named Solaris)
1.0.1 4.1.2 2.0 6[379]0-1[24]0 MP
1.1 4.1.3 3.0 SP Viking support
1.1C 4.1.3C 3.0 Classic/LX
1.1.1 4.1.3_U1 3.0_U1 4.1.3 + fixes + Classic/LX support
1.1.1 B 4.1.3_U1B 3.0_U1 1.1.1B + SS5/SS20 support
1.1.2 4.1.4 3_414 The "final" 4.x release (SS20 HS11)
2.0 5.0 3.0.1 sun4c only
2.1SPARC 5.1 3.1 Dec '92
2.1 x86 5.1 3.1 May '93
2.2SPARC 5.2 3.2 May '93
2.3SPARC 5.3 3.3 Nov '93
OpenWin 3.3 is X11R5 based: Display
PostScript instead of NeWS, no SunView.
It is still primarily OPEN LOOK.
The Spring 1995 OpenWin will be Motif
and COSE-based.
Statically linked BCP support
2.3 edition II SPARC Special Solaris 2.3 distribution for
Voyager and SparcStation 5
2.3 hardware 5/94 SPARC ??
2.3 hardware 8/94 SPARC Supports S24 (24 bits color for SS5),
POSIX 1003.2, Energy Start power management
and SunFastEthernet + patches.
2.4 5.4 3.4 From this moment on, the SPARC and x86
releases are in sync. Q3 '94
Adds motif runtime and headers (not mwm).
2.4 hardware 11/94 First SMCC release of 2.4
2.4 hardware 3/95 Second SMCC release of 2.4 (includes support
for booting from SSA)
2.5 5.5 3.5 UltraSPARC support, PCI support.
NFS V3, NFS/TCP, ACLs, CDE, Sendmail V8
name service cache, dynamic PPP
Posix threads, doors (new IPC mechanism)
many "BSD" type functions back in libc,
many "BSD" programs back in /usr/bin.
mixed mode BCP support (e.g., apps only
dynamically linked against libdl.so)
2.5 hardware 1/96 Creator3D support (Creator3D/FFB+ is not
supported in 2.5 11/95, though the files
are present but of unsupported,
"mostly works", beta quality)
2.5.1 Ultra-2 support, Sun Enterprise
server support. Large (32bit UID)
support. 64bit KAIO (aioread64/aiowrite64),
3.75 GB of virtual memory.
Pentium/Pentium Pro optimizations.
(upto 25% for certain database apps)
Ultra ZX support.
Initial and last PowerPC desktop release.
2.6 5.6 3.6 Largefiles, JVM + JIT, Hotjava,
Web based answerbook, BOOTP/DHCP, SNMP agents,
VLSM, in-kernel sockets, NTP, PAM,
CDE 1.2 as default desktop.