Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!mcsun!ukc!strath-cs!cs.glasgow.ac.uk!bru-cc!eesrajm
From: eesrajm@cc.brunel.ac.uk (Andrew J Michael)
Newsgroups: comp.os.minix
Subject: Re: Help, need 68k HW info for minix68k to build dedicated minix HW
Summary: Don't use a 68008
Keywords: Hardware, memorymap, ticks
Message-ID: <1342@Terra.cc.brunel.ac.uk>
Date: 13 Feb 90 17:01:09 GMT
References: <1990Feb8.092653.4350@ericsson.se>
Organization: Brunel University, Uxbridge, UK
Lines: 33

Bosse Sandholm writes
>For our 68008 minix version we plan to buy atari-minix and start from there.

My advice is don't use a 68008.  I tried to run MINIX on a 68008 about a year
ago, and gave up because the 68008 isn't fast enough.  Sounds odd ??? 
Well ....

Consider the code in stfloppy.c, which tells the 1772 to carry out a command
and then waits for an interrupt when it has finished.  But suppose that the
1772 carries out the command very quickly (like a restore when the head is
already at track 0).  On a 68008 at 8MHz, the processor didn't exit from
the code setting up the controller fast enough, and a hardware interrupt 
appeared before the driver was ready to expect a signal.  Result; one broken
operating system.

On a 10MHz 68008 you might be OK, but bearing in mind that the 68008 only
has a 1Mb addressing range and is hardly likely to set the world on fire
with its speed, why bother ?

I have run MINIX on a 68020 board for nearly two years now.  In its current 
form (20MHz, no wait states) it delivers 6210 dhrystones/sec with a gcc
compiled kernel and dhry.c.

>Can a PC read the atari minix diskettes?

No, due to endian problems. However, you can transfer files via tar, provided
you have a recent version of tar on both machines.

>Can anybody supply us with the gcc 68000 crosscompiler for minix on a sun?

Certainly, if you canot find anyone nearer.  Drop me a line.

Andy Michael