From: woodman@bnr.ca (Dave Woodman)
Newsgroups: comp.os.misc
Subject: Re: Minix for the QL (was Re: QL serial lines)
Keywords: QL QDos
Date: 11 Apr 92 12:31:22 GMT
Organization: BNR Europe Ltd, Maidenhead

In article <1992Apr10.224926.29072@klaava.Helsinki.FI> torvalds@klaava.Helsinki.FI (Linus Benedict Torvalds) writes:
>In article <1992Apr09.164408.24670@bnr.uk> woodman@bnr.ca (Dave Woodman) writes:
>>
>>  Well (and Linus, you might not want to hear this, given your recent 
>>efforts), there is Minix available for QDOS...
>
>Oh yes, I'm definitely interested - especially if it is available as
>patches against PC-minix (but I assume they started off with a 68k
>port?).  Can somebody tell me how they did it? (and who are "they"
>anyway?) I know writing a floppy-driver wouldn't be much fun: with no

'They' is a him. The particular 'him' in question is Dave Walker
(d.j.walker.lon4905@oasis.icl.co.uk). And yes, it used to be ST Minix,
but it's getting better now...

>DMA I had to really optimize things in order to read the programmed IO
>for my own driver, and I think I never got it to work from basic ram
>(had to use eproms or expansion-ram - the inner loops that read the IO
>addresses were really tight: I was unable to use a cmp, had to use a
>subq, I think, to save a couple of cycles.  Something like that... 
B
>Debugging was hell :^). 
>
>Or does it all work on top of QDos? Much easier, but not as much fun. 
>But it /would/ be fun to refer to the microdrives as /dev/rmt0 :)

Yes again, it is implemented as a job under QDOS. I'm still waiting for my copy,
but apparently you have the choice of writing to devices directly, or using a 
QDOS file as a 'partition,' ie, the system sees the file as a device. With my
hardisk and Gold Card (16 MHz 'proper' 68000 and 2M RAM) this should serve 
quite nicely...

>
>Does QL-minix use the QDOS for multitasking too? Or does it use it's own
>scheduler within one QL task or what? Running atop QDOS should mean you
>can run minix while at the same time using SB and any other QL tasks -
>true or false?
>

As I say, I don't have my copy yet, but I would imagine that it uses it's own
scheduler. And yes, the author tells me that SB would be available, dependant 
on how much memory has been allocated to Minix. This might prove to be a 
problem on a 640K QL, but should prove quite possible on one with 896K (Trump
Card) or 2M (Gold Card).

>>  Most of your other problems have since been fixed, including the problem
>>with lack of power, and further developments are close.
>
>Well, there were newer versions of the QL coming out even while I was
>still active, so I'm not too surprised - with a reasonably fast 68020 or
>better and a better memory subsystem it might be a real pleasure to use. 
>I always liked QDos - one of my few gripes with it was the inability to
>use the second screen without disabling most of the system software (and
>being unable to map all the interrupts - I'd have liked to use the a-
>and f-line exceptions and some other things...)
>

The second screen is available under the Minerva ROM:- re-written QDOS. The 
Gold Card (again) shadows the internal RAM so making the basic QL hardware
much less relevant to the user. I'm afraid that the original set of 'mappable'
vectors remains the same, although QUANTA will supply you with a disk 
containing a disassembly of the ROMs with which you may do as you will. With 
then new QL compatible coming from Miracle soon, you won't be forced to use 
a lowely 68020 either:- they wern't impressed with the improvemant over the 
Gold Card...

>>							  The only thing
>>left is the problem of the RS232 interface giving problems. For a clue to
>>this, watch the handshake used on receive:- this is not held steady, even
>>on an idle line.
>
>If this was in the original specs, it might explain my problems: I never
>had access to an oscilloscope to test it all out.  It's a bit ironic
>that this would still be a problem - serial lines aren't exactly hard to
>handle, and it's a pity the QL didn't use more standard parts for them. 
>Some of the hardware solutions in the QL were definitely "interesting" -
>I assume it was cheaper that way originally, but it did hurt the
>reputation of the machine.

  Even this had a fix long ago:- an intelligent RS232 interface from Tandata.
This beastie is called the QCONNECT, and allows split-baud, gives you the 
ability to set a speed other than the main port speed, and provides a much
fuller RS232 signal set. 

>
>I fixed some of my problems with a better power-supply and regulator
>(home-brew, but they seemed to work), as well as additional heat-
>dissipation.  A pity really: I shouldn't have needed to, and I had a
>number of weird crashes before I got it all together.

Crashing was never one of my problems (unless I coded badly!), but the various 
ways of stopping these have been well documented for those of us that suffer.
I agree, though, you shouldn't have needed to put in the work.
>
>		Linus

Anyway, to give you an idea, here I am at home, in front of my trusty QL (no
other computers here!), 16MHz 68000 CPU, 2M RAM, Tandata QCONNECT chatting to 
my modem at 2400 baud, 40M hard disk, and yes, it is a pleasure to use. Oh, 
I have a 'real' keyboard on it too! All I need to do now is get some ED floppy
drives...

		Cheers,

			Dave.

-- 
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Newsgroups: comp.os.minix