1991 Review of Coherent
Before Linux (just before Linux), there were other attempts
to bring a Unix-like OS to the masses. I came across this review
that I wrote in 1991.
I am writing this article using MicroEMACS under Coherent. Using
EMACS may not be an intelligent choice; I am totally unfamiliar
with it (I'm a vi user from way back), and am undoubtedly mere
keystrokes away from losing everything. However, this knowledge does
add excitement to the undertaking. Some people sky-dive; I write
with unfamiliar tools. Same thing, I think.
If you have somehow missed the full page ads in Byte, and have ignored
the spirited discussions on Bix and Prodigy and everywhere else, you
may not be aware that Coherent is a $99.95 Unix clone. The general
heightening of interest in Unix has put this product in the right
place at the right time. There is a lot of Unix curiosity out there,
and Coherent is a cheap way to take a test drive.
Coherent is sparing of your hard drive. You can install it
in as little as 7 megabytes (more is better, of course). If
I install SCO Xenix, it of course is much more expensive but also
requires 40 megabytes of precious drive space.
Coherent isn't really comparable to SCO. The SCO Xenix manual set
occupies more cubic inches than my computer itself; Coherent has
one manual (1,000+ pages). Coherent has 4 install disks; SCO's
set won't even fit in two thick plastic disk cases. Coherent costs
just under $100.00; SCO Xenix (with the development system) is ten times that.
SCO really does take half a day to install (I do this for a living) while
Coherent really does only take a half hour to a running system. Finally,
I definitely have not been recommending Coherent for business use!
I have been enthusiastically recommending Coherent to people
who want a taste of what Unix is all about, as a learning tool -
"Learn Unix at Home" or something like that.
Coherent is not without its detractors. I have seen some bitter
diatribes detailing its limitations, its bugs, and its deviation from
The True Path. I can only wonder what these sour-pusses expected
for their hundred dollars. This is a complete and working operating
system with a C compiler, an assembler, a debugger, support for DOS
disks, support for uucp, three editors (ed, vi and emacs), complete
manual pages on-line, support for multi-port serial cards and scsi drives,
games, mail, ram disks and some 200 typical Unix commands. In other
words, it may be a toy, but it is a finely engineered, highly crafted
and lovingly detailed plaything. Foo on the nay-sayers!
One complaint I have heard stems from the fact that the C compiler
only supports "small model" programs - that is, 64K of code and 64K of
data. One person I talked to insisted that you can't write "real"
programs with such limitations. No, I suppose you can't write the
next Lotus-killer on Coherent. You could write something better than
Visicalc though - the original of that ran on Z80's with
less than 48K of total memory! "Real" programs, indeed!
Another constant carping concerns uucp. Coherent's version is
certainly not the latest, and has a few traps for the unwary. However,
that's not unusual with uucp. I don't think anyone has ever set up
uucp correctly the very first time on a new system. Even I managed
to get it wrong more than once, but it was just
carelessness, haste and not bothering to read the manual that caused
all my problems.
Coherent's /bin/sh lacks some niceties and has some bugs. You
can't define a shell function. You can't include a new-line inside
double quotes (though you can with single quotes). There are a few
other little omissions and sins which the nit-pickers can tell
you all about.
The manual has taken its share of criticism. Rather than dividing
the commands into the traditional sections, Coherent has produced a
"Lexicon", which just lists everything alphabetically - commands,
library functions and all. Apparently the division of commands
into sections was ordained by some omnipotent being; the Coherent
haters certainly see this organization as blasphemous! I actually
like the manual. It includes definitions of terms for people new to
Unix or new to computing. For example, all of the following
address, alignment, arena, array, bit, bit map, buffer, byte,
cast, daemon, executable file, field, file, FILE, file descriptor,
filter, function, GMT, i-node, interrupt, lvalue, macro,
manifest constant, modulus, NULL, nyblle, object format, operator,
pattern, pipe, port, precedence, process, random access, ranlib,
read-only memory, register variable, root, rvalue, stack, standard error,
standard input, standard output, sticky bit, stream, structure,
superuser.. and more.
These aren't chintzy little definitions, either. Most are
at least half a page and some run two or three pages of unusually
lucid explanation. I can't think of any other place where as
much Unix related material is packed between two covers.
All in all, this has to be worth much more than the price charged.
If you need to learn because your boss has decided to "Unix" the
place, or if you are the boss and want to get a feel for the
territory, this is for you. You'll get at least a hundred hours
of fun (it will take you that long to try everything out) so it's
pretty cheap entertainment if nothing else.
I think I still have that Coherent manual here somewhere,
but I can't find it right now. It may have gotten tossed out
with the old BSD 386 manuals and the early Linux CD's. I wish
I could keep all this old stuff, but there's just too much of it.
Got something to add? Send me email.
Increase ad revenue 50-250% with Ezoic
More Articles by Tony Lawrence
Find me on Google+
© 2015-04-02 Tony Lawrence