I had no idea there was a unix-like available at relatively reasonable cost before Linux. How is the c compiler, is there any way to compile some modern software for this?
That right there will be an even bigger showstopper for the build scripts of most things than anything else. During the early 90's we could run GCC and Comeau C++ and all that kind of thing on Coherent fine because those codebases were still built for wide portability even though things like BSD FFS had opened that up - there were still plenty of machines running System III and System V code that most people took care not to create gratuitous collisions if truncation happened. Even shortly post the advent of Linux, that had changed dramatically and basically turned on its head and the effort involved in backporting to any flavour of classic UNIX (not just Coherent) quickly became almost impossible.
The final releases of Coherent (4.2 is the last one IIRC) also fully supported the iBCS COFF binary standard, so binaries compiled for e.g. SCO Unix might work.
You could also try to build an old gcc version with the provided K&R compiler: https://www.autometer.de/unix4fun/coherent/coh_prog.html
I don't know about the current state of Coherent support, but the Wikipedia page has some resource links.
https://en.wikipedia.org/wiki/Coherent_%28operating_system%2...
That is why I posted the link.
Linux was not the first low-cost Unix for the PC.
Very roughly, it went:
* Unix only ran on proprietary kit. PCs were too small.
* The 286 came along, and SCO took over Microsoft Xenix and offered it as a 286 OS -- expensive, and stuff we take for granted now, like networking, X11, and a compiler, were all separate expensive extras.
* The 386 made Xenix a very credible usable OS, but it cost 10x as much as DOS or Windows. Commercial deployments in business, with no GUI, no networking, no compile, just statically-linked proprietary apps and dumb RS-232 terminals, mostly from Wyse.
* As PCs got more powerful, other companies offered expensive PC Unixes too, and SCO officially licensed the AT&T kernel: SCO Xenix became SCO Unix.
* Coherent came along with a very cheap and complete (but very limited) Unix-like OS.
* Minix came along, even cheaper and you could get the source code.
* It became possible to build and run BSD on PCs if you were a serious guru.
* GNU considered the BSD kernel and decided against it, going for Mach and the HURD instead. (Oops.)
* Linux came along and undercut Coherent, putting the MWC out of business.
* NetBSD and FreeBSD became somewhat usable if you were highly capable.
* Linux gradually became somewhat usable as a mainstream OS, with things like live CDs (Yggdrasil, Lasermoon Linux-FT) and installable modular distros with packaging (Red Hat Linux, Debian).
For 32-bit Coherent (4.0.0 and later) there is some 2.x GCC, but I have never used it and I doubt that it can compile software that is "modern" these days.