TI MSP430

larwe wrote:
> Gary Reichlinger wrote:
> 
>>>basis of its similarity to the PDP-11(1).
>>
>>      Do you guys belong to AARP?
> 
> Not yet, but the curmudgeonliness flux density is high in the
> engineering field, so it's forgivable that you would ask the
> question :)

What we really need is a PDP-8 on a chip.

-- 
"If you want to post a followup via groups.google.com, don't use
 the broken "Reply" link at the bottom of the article.  Click on 
 "show options" at the top of the article, then click on the 
 "Reply" at the bottom of the article headers." - Keith Thompson
More details at: <http://cfaj.freeshell.org/google/>
Also see <http://www.safalra.com/special/googlegroupsreply/>

On Sun, 09 Apr 2006 07:47:17 -0400, CBFalconer <cbfalconer@yahoo.com>
wrote:

>larwe wrote:
>> Gary Reichlinger wrote:
>> 
>>>>basis of its similarity to the PDP-11(1).
>>>
>>>      Do you guys belong to AARP?
>> 
>> Not yet, but the curmudgeonliness flux density is high in the
>> engineering field, so it's forgivable that you would ask the
>> question :)
>
>What we really need is a PDP-8 on a chip.

Actually, Lewin appears to be working on something older.  I think his
ulterior motive, though, is to give those "curmudgeons" here something
to go waste their time on so that his competition dwindles away and
he's in a better position towards his goal of world domination.  ;)

Jon

P.S.  Although I worked on PDP-8s, recall the 14" drive patters, the
DecTapes, and kicking an 8k drum memory to get it working again, I
don't really like the instruction set that much today.  Still have my
pdp-8 manuals around, though.  And the little nifty instruction card.

Jonathan Kirwan wrote:
> CBFalconer <cbfalconer@yahoo.com> wrote:
>> larwe wrote:
>>> Gary Reichlinger wrote:
>>>
>>>>> basis of its similarity to the PDP-11(1).
>>>>
>>>>      Do you guys belong to AARP?
>>>
>>> Not yet, but the curmudgeonliness flux density is high in the
>>> engineering field, so it's forgivable that you would ask the
>>> question :)
>>
>> What we really need is a PDP-8 on a chip.
> 
> Actually, Lewin appears to be working on something older.  I think
> his ulterior motive, though, is to give those "curmudgeons" here
> something to go waste their time on so that his competition
> dwindles away and he's in a better position towards his goal of
> world domination.  ;)
> 
> P.S.  Although I worked on PDP-8s, recall the 14" drive patters,
> the DecTapes, and kicking an 8k drum memory to get it working
> again, I don't really like the instruction set that much today. 
> Still have my pdp-8 manuals around, though.  And the little nifty
> instruction card.

I first encountered one before getting into computers at all, when
on a visit to Berkeley circa 1963 I found an old acquaintance
(forget his name, but a physicist from AECL, Chalk River) had
acquired one.  It was a marvel of compactness - occupied only one
relay rack, together with the free standing ASR33.  Didn't even
require conditioned power lines, IIRC.

-- 
"If you want to post a followup via groups.google.com, don't use
 the broken "Reply" link at the bottom of the article.  Click on 
 "show options" at the top of the article, then click on the 
 "Reply" at the bottom of the article headers." - Keith Thompson
More details at: <http://cfaj.freeshell.org/google/>
Also see <http://www.safalra.com/special/googlegroupsreply/>

larwe wrote:
> Marc Ramsey wrote:
> 
> 
>>>MSP430 is a truly elegant architecture, there's no denying it. von
>>
>>Of course, the architecture is a simplified version of the TMS9900 CPU,
>>which was derived from the TI 990 minicomputer, which was in turn a
>>rip-off of the PDP-11 ISA, with slight changes (fewer addressing modes,
> 
> 
> LOL. You know, writing this most recent book is so amusing. I think I
> could probably use 75% of it as responses in c.a.e.
> 
> "Now, it's an obscure but well-recognized ritual amongst engineers and
> computer scientists to gauge the architecture of any new device on the
> basis of its similarity to the PDP-11(1). The strongest term of
> approbation you can use for a CPU design is to say "It's just like a
> PDP-11!". Exactly why this is universally regarded as a Good Thing is
> not exactly clear, but in any case, this epithet is frequently applied
> to the MSP430. (I've always felt that this is the same sort of
> statement as saying "My 2007 Mercedes convertible is just like a 1965
> International Harvester Scout light truck. They both have pneumatic
> tires and a removable roof!"). What I think these people probably
> mean is that the MSP430 has a very nice orthogonal instruction set and
> simple memory addressing scheme.

Funny.  When I looked at a PIC, my
first reaction was that "it was just
like a PDP-8".

Gary Reichlinger wrote:

> On 8 Apr 2006 17:43:20 -0700, "larwe" <zwsdotcom@gmail.com> wrote:
> 
> 
>>"Now, it's an obscure but well-recognized ritual amongst engineers and
>>computer scientists to gauge the architecture of any new device on the
>>basis of its similarity to the PDP-11(1). 
> 
> 
>      Do you guys belong to AARP?  


Personally, no.  But I could join if
I wanted. (:

CBFalconer wrote:
> larwe wrote:
> 
>>Gary Reichlinger wrote:
>>
>>
>>>>basis of its similarity to the PDP-11(1).
>>>
>>>     Do you guys belong to AARP?
>>
>>Not yet, but the curmudgeonliness flux density is high in the
>>engineering field, so it's forgivable that you would ask the
>>question :)
> 
> 
> What we really need is a PDP-8 on a chip.


Rather not - but some PIC's are pretty close with all
the built-in limitations of a PDP-8.

My vote to PDP-11.

Been there - used both, a couple of years ago.

-- 

Tauno Voipio
tauno voipio (at) iki fi

Gary Reichlinger <reichln@navix.net> writes:
> On 8 Apr 2006 17:43:20 -0700, "larwe" <zwsdotcom@gmail.com> wrote:
> 
> >"Now, it's an obscure but well-recognized ritual amongst engineers and
> >computer scientists to gauge the architecture of any new device on the
> >basis of its similarity to the PDP-11(1). 
> 
>      Do you guys belong to AARP?  

Watch your mouth there, you young whippersnapper!
We do not mention the "O" word in polite company.

In article <4438F445.5EF07B7D@yahoo.com>, cbfalconer@yahoo.com says...
> larwe wrote:
> > Gary Reichlinger wrote:
> > 
> >>>basis of its similarity to the PDP-11(1).
> >>
> >>      Do you guys belong to AARP?
> > 
> > Not yet, but the curmudgeonliness flux density is high in the
> > engineering field, so it's forgivable that you would ask the
> > question :)
> 
> What we really need is a PDP-8 on a chip.
> 
> 
"He who does not study is doomed to repeat it."
(couldn't track down the author).

Intersil 6100.

Mark Borgerson

Jonathan Kirwan wrote:
> On Sun, 09 Apr 2006 00:16:04 GMT, Marc Ramsey <marc@ranlog.comREMOVE>
> wrote:
> 
>> larwe wrote:
>>> MSP430 is a truly elegant architecture, there's no denying it. von
>>> Neumann simplicity, totally transparent handling of registers and
>>> addressing modes; I really can't find much to fault with it (except
>>> maybe the way info memory is handled). But:
>> Of course, the architecture is a simplified version of the TMS9900 CPU, 
>> which was derived from the TI 990 minicomputer, which was in turn a 
>> rip-off of the PDP-11 ISA, with slight changes (fewer addressing modes, 
>> allowing twice as many registers) to avoid patent issues...
> 
> I have a few comments about a pdp-11 comparison at:
> 
>   http://users.easystreet.com/jkirwan/new/msp430.html
> 
> Jon

Your comments are (as far as I can tell) factually correct, but the 
reaction that springs to mind is "so what?".  As an embedded programmer, 
I really do not care how a particular embedded micro compares to an old 
minicomputer cpu (other than for historic interest, of course - in which 
case it definitely is interesting).  And as for possibly misleading 
marketing from TI - it's not exactly new or unusual!

What is much more relevant is whether the register set and addressing 
modes of the msp430 really are appropriate for their target 
applications, or whether they would have been better off with the PDP-11 
arrangement.  I'm far from convinced - certainly, the example you gave 
(PC-relative CALL) is obscure indeed, and I think the benefit of more 
registers well outweighs this missing feature.

One thing that is definitely missed, however, is all four addressing 
modes as the destination for two-operand instructions.  At the very 
least, there should have been a hack in the MOV instruction to allow @Rn 
and @Rn+ modes in the destination.

As for the missing PDP-11 addressing modes, they are not such a great 
loss.  The indirect modes are almost entirely superfluous when you have 
enough registers to hold pointers in registers, rather than having to 
have them in memory or on the stack.  It's not often that pointers to 
pointers turn up, at least not in embedded programming.  Auto-decrement 
modes are nice, but how often are they used in practice?  *(p++) far 
outweighs *(--p), as long as you have a stack pointer and push/pop 
instructions.  Perhaps it would be a useful mode for MOV, but not otherwise.

So if you want to say that the msp430 is not as close to the PDP-11 as 
TI marketing seems to think, then I fully agree.  But if you think 
that's a bad thing, then I disagree.

mvh.,

David

Mark Borgerson wrote:
> In article <4438F445.5EF07B7D@yahoo.com>, cbfalconer@yahoo.com says...
> > larwe wrote:
> > > Gary Reichlinger wrote:
> > >
> > >>>basis of its similarity to the PDP-11(1).
> > >>
> > >>      Do you guys belong to AARP?
> > >
> > > Not yet, but the curmudgeonliness flux density is high in the
> > > engineering field, so it's forgivable that you would ask the
> > > question :)
> >
> > What we really need is a PDP-8 on a chip.
> >
> >
> "He who does not study is doomed to repeat it."
> (couldn't track down the author).
>
> Intersil 6100.

Many years ago DEC was giving away sample chips with a PDP-11 on them.
I got one and started to design a small system round it, but never got
round to building it.

Leon