Help, need 68k HW info for minix68k to build dedicated minix HW

Help, need 68k HW info for minix68k to build dedicated minix HW

Post by Bosse Sandho » Fri, 09 Feb 1990 18:26:53



We are a 5 people with mostly HW experience who want to build a 68008 computer
to run minix.

I have patched pc-minix up to 1.5.0 on my sun, i have not yet installed it on a pc.
For our 68008 minix version we plan to buy atari-minix and start from there.
To simplify the software labour we want to design the 68008 card as atari-
compatible as possible.

I have a few questions to those of you who have looked more deeply into
minix-68k and it hw-needs.

We are thinking of building the card with the following memory map,
how does it compare with atari?

        f0000-fffff  bootprom and monitor 64Kb
        e0000-effff  i/o
        00000-dffff  RAM  (bootprom shifted to lowest address during first 8
                           cpu cycles after reset.)

I/O     68681   two serieports, our monitorprogram supports this chip
                what serialports does minix68k support?
        2797    WD floppy controller, what does minix68k support?

TIMER   What rate of clock tick is minix68k setup for and what chip does
        atari support?
SCSI    We have not really been thinking of this yet, how is it implemented
        in atari.
What memory adresses does atari use for it's periferal chips.

Can atari minix diskettes be read by any other computer than an atari,
we would like to get atari 68k src to a sun for patching and archiving.
Can a PC read the atari minix diskettes?

Can anybody supply us with the gcc 68000 crosscompiler for minix on a sun?
We do not have ftp access.

If you can help us please respond.

Bo-Erik Sandholm
TN/ETX/TT/HL                    phone +46 8 719 1658
Ericsson telecom                Fax   +46 8 719 5319
126 25 Stockholm

..!uunet!sunic!ericom!snoddas!bosse

 
 
 

Help, need 68k HW info for minix68k to build dedicated minix HW

Post by Andrew J Micha » Thu, 15 Feb 1990 02:01:09


Bosse Sandholm writes

Quote:>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.

Quote:>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.

Quote:>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

 
 
 

1. 68k HW context registers

I saw some discussion floating around about using minix with a 68k MMU. Has anyone
gotten this sort of thing to work, and if so, on which processors (68000 w/PMMU, 68030,
etc.)?

How many context registers does a 68030 have anyway?

Post or Email.
Will summarize if warranted.

--

---
Dietrich Kappe

Center for Population Economics

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