Date   : Tue, 20 Sep 1988 22:00:52 GMT
From   : well!bandy@hplabs.hp.com (Andrew Scott Beals)
Subject: z-80 unix and unix-"like" shells

Let's clear things up.  There are three general classes of
objects that people are talking about:
       
       * Unix-like shells (CCP replacements)
       * Unix-like operating systems (ground-zero efforts)
       * Unix ported to the z80

Of the first class, Unix-like shells, there are any number, of which,
CNIX and MicroShell come to mind.  These allow you to do i/o redirection,
type multiple commands on a line and do "pipes" (not real pipes as the 
programs are executed sequentially).  These make using your CP/M
programs a bit more palitable, as the CCP is pretty ugly.

The second class are microcomputer operating systems designed to look
and feel somewhat like Unix. 

Mark Davidson mentioned an effort which was described to the C User's
Group a number of years ago.  This was the Marc operating system -
unfortunately I don't remember the name of the gentleman who did most
of the work on it, but when he died (due to an accident), Lauren
Weinstein (yes, that Lauren) took over the project for a while, but
decided to retire it when it simply got too big to run on the micros of
the day (this was around 1981).

Another effort in the unix look-alike class is the Cromix operating
system from Cromemco.  Yes, they're still in business and they still
maintain a uucp site.  They make postings every once in a while.
I'm not sure that Cromix runs on a z80, but I have heard that it
does.  Cromix also runs on Cromemco's 68000 machines and a port was
done to the Amiga by a gentleman who lives in the Great Northwet -
when he was down here during the summer he told Cromemco about it,
but I don't know what they thought of it.  He just re-wrote the i/o
drivers to get it working in glass-tty mode (no windowing system).

As to real live Unix for the z80, after Morrow Designs did their
MPU80 board, Unisoft did a v7 port (perhaps v6?) to that cpu.  The
MPU80 provides a number of features lacking in the z80, namely
memory mapping, decent arithmetic, kernel&user modes and instruction
traps.  User-mode processes aren't allowed to do (this is from
memory) i/o instructions or halts - the kernel is called whenver
a user process attempts such an instruction.  With the additional
hardware, a z80 starts to look like an 8-bit PDP-11.


For those of you with a yen to hack, you also might want to consider
doing a Minix port to your machine - if it has sufficient memory
and can map memory easily enough.
-- 
Andrew Scott Beals                  Ridu dum tiam vi povas, simiulo-knabo!
bandy@lll-crg.llnl.gov or {pacbell,lll-crg,hoptoad,hplabs,apple}!well!bandy


End of INFO-CPM Digest
******************************