LispOS on a 68000

[Greg Menke]

I hate to insert the evil "I", but there are some high integration x86
cpus, which makes homebrewing lots easier.  Onboard serial, digital I/O,
interrupt hardware and address decoding- that sort of thing.  AMD makes
some nice, fast 186/386 variants as well.  Somewhat farther afield,
Siemens/Dallas/Philips make some FAST 8051 variants- pretty slim on the
memory side, and no MMU, but circuit-wise they're simple and have lots
of free tools and code available.

Super-capable machines are great, but its satisfying to roll your own
dumpy little rig, load it up yourself and see it run-  even if it can't
do the really big jobs.

Gregm



Mike McDonald wrote:
> 
> >From lispos-request@math.gatech.edu  Thu May 14 12:18:04 1998
> >Resent-Date: Thu, 14 May 1998 14:46:43 -0400 (EDT)
> >Date: Thu, 14 May 1998 13:47:32 -0500
> >From: David Tillman <dtillman@cannonexpress.com>
> >To: lispos@math.gatech.edu
> >Subject: LispOS on a 68000
> >Resent-Message-ID: <"6r67o2.0.a75.JmpMr"@math>
> >Resent-From: lispos@math.gatech.edu
> >X-Mailing-List: <lispos@math.gatech.edu> archive/latest/2316
> >X-Loop: lispos@math.gatech.edu
> >Resent-Sender: lispos-request@math.gatech.edu
> >
> >
> >
> >
> >    How feasible would a Lisp/Scheme OS be on a 68000?
> >
> >    Please realize that I am in question-asking-mode here. I have no
> >    idea how Lisp internals are implemented. I am thinking about putting
> >    together a homebrew 68000 or 68030 and it would be nice to run
> >    something besides Forth on it. My concerns are:
> 
>   Wow! I haven't heard of anyone trying to hack a homebrewed system in
> years! Everyone seems to just buy an already built motherboard (most
> likely, a PC one) and then hack software. Sounds like fun. (Really
> sounds like things from my past. Say fifteens years ago! Anyone
> remeber a thing called the "Big Board"?) Are you building your own MB
> to learn how or what?
> 
> >        a. Speed - If I wirewrap it, I will be stuck to around 8-10MHz.
> >           Not exactly blazing. If I use a 68030, I will probably knock
> >           out a couple PCBs for it and speed won't be quite so much an
> >           issue.
> 
>   The 68030 would probably be nicer because of the MMU. Having a MMU
> under your control can be useful for things like garbage collection.
> 
> >        b. Implementation - I don't know enough about Lisp to actually make
> >           my own (not a pretty one, anyway). I could probably hack together
> >           some Lisp/Scheme looking thing, but that wouldn't be quite the same.
> 
>   Nah, it'd be BETTER! If you're going to build your own machine, why
> make it look like everyone else's? I was thinking that CMUCL might be
> a good base to start with but I don't think it has ever been ported to
> the 68Ks. Seems like it should be doable though. One thing that would
> be nice is support for multiple processes (aka threads). Then you
> could eventually have things like network deamons running in the
> background. Hmm, if the CADR code is ever found, that'd make an
> interesting base to work with. (In case you don't know, the CADR was a
> lisp machine built by MIT years ago. Same basic class of machine as
> you're talking about but built specificly to run lisp.)
> 
> >    Thoughts? Has this road been covered before? I would probably just
> >    communicate with it by way of serial at first; a nice bitmapped display
> >    wouldn't be too hard though.
> >
> >    -Dave
> 
>   Oh, we've yacked about the same type of thing for over a year now
> and some 2000+ messages! :-) We've been assuming the use of a standard
> PC as the machine though. Everything else has been an endless
> argument.
> 
>   Have fun and don't be afraid to go your own way!
> 
>   Mike McDonald
>   mikemac@mikemac.com