[TUHS] Need a new PDP-11 or VAX?

[TUHS] Need a new PDP-11 or VAX?

[David Barto]

Larry McVoy said:
On Apr 28, 2013, at 7:00 PM, tuhs-request at minnie.tuhs.org wrote:

> We build source management systems and we still drop into assembler for
> some stuff.  For example, we want to give ourselves a stack traceback
> when something dies.  Another example is inner loops that are performance
> critical, we stare at the assembler.

I don't mind staring at the assembly, I just don't want to hand crank it any longer. :-/

I'll spend quite some time fussing with the compiler and optimization flags to get loops to run at maximum speed before I'll take the assembly in hand to 'make it right.'

For stack traces, I've found the GNU compiler support for stack tracing quite handy and for my company it works quite well.

On the discussion of x86 assembly, I have to agree that it is horrific. I'll take ARM (and I have done context switchers and trap handers in ARM) any time.

	David Barto

/my name in your iPhone, it is more likely than you think.

[TUHS] Need a new PDP-11 or VAX?

[Ronald Natalie]

> 
> For anyone who's into really CISC architectures, check out the iAPX432.
> 
> -

Ah, the Ada chip.   Biggest problem is by the time it was available, it was beastly slow compared to just about everything else out there.

[TUHS] Need a new PDP-11 or VAX?

[Peter Jeremy]

On 2013-Apr-27 15:41:46 -0700, Larry McVoy <lm at bitmover.com> wrote:
>What I'd like is a new 64 bit PDP-11.

That might be fun to program in assembler but I suspect the
performance would suck.  The ISA complexity implies a microcoded
implementation (with all the associated overheads).  And compilers
generally have difficulty taking advantage of complex ISAs.

>  That assembler was wonderful to
>read and write, only a short distance from C.

Agreed.

>  x86 makes me puke.

Likewise.  Warts upon warts...  It's an abomination.

>  MIPS
>and Alpha aren't much better (I was hoping for better from Alpha but they
>seemed like they copied MIPS).

I disagree on the Alpha.  Apart from the idiotic decision to combine
imprecise exceptions with needing software support for IEEE FP, I
thought it was a very clean and well designed architecture.  It wasn't
fun to program in directly but it was intended for use with compiled
languages.  The designers went to a fair amount of effort to avoid
embedding bottlenecks in the language.

For anyone who's into really CISC architectures, check out the iAPX432.

-- 
Peter Jeremy
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[TUHS] Need a new PDP-11 or VAX?

[John Cowan]

Larry McVoy scripsit:

> Ideally with 32 bit ints, 64 bit longs, 32 or 64 bit pointers in the 
> compiler, obviously more registers, and nothing like the vax.        

Sounds right.  I'm torn between the 8 addressing modes of the PDP-11 and
32 registers, or the 16 addressing modes of the Vax and only 16 registers.
In either case, 32-bit instructions allow all operands to have full
addressing mode on both source and destination rather than just a register
for one or the other.  The byte/word bit of the memory instructions would
become 2 bits for byte/short/int/long.  One issue is whether to have
a single 32-bit index in modes 6 and 7, or provide a full 64-bit index
with two trailing 32-bit words.  Branches can have much bigger offsets,
which is good.

The FPP needs a complete overhaul: it should look pretty much
like the main ISA, and of course use IEEE format operands.  Hmm,
perhaps get *really* modern and use 3 bits of size for byte/short/
int/long/float32/float64/decimal64/decimal128, where the last two are
IEEE 754:2008 decimal floating point values.

> I'm too dumb to get it but I never warmed up to the vax.

When I saw it had 256 opcodes I knew I was never going to master it, no
matter how orthogonal it was.  (I came from the PDP-8 to the PDP-11.)
Little did I know the Last ISA would have thousands and thousands of
opcodes!

-- 
Note that nobody these days would clamor for fundamental laws        John Cowan
of *the theory of kangaroos*, showing why pseudo-kangaroos are   cowan at ccil.org
physically, logically, metaphysically impossible.    http://www.ccil.org/~cowan
Kangaroos are wonderful, but not *that* wonderful.     --Dan Dennett on zombies

[TUHS] Need a new PDP-11 or VAX?

[Larry McVoy]

On Sat, Apr 27, 2013 at 09:39:11PM -0400, John Cowan wrote:
> Larry McVoy scripsit:
> 
> > What I'd like is a new 64 bit PDP-11.  
> 
> With a 16-bit instruction stream still, or with wider instructions and
> more registers, almost but not quite entirely unlike the Vax?

Ideally with 32 bit ints, 64 bit longs, 32 or 64 bit pointers in the 
compiler, obviously more registers, and nothing like the vax.  Maybe
I'm too dumb to get it but I never warmed up to the vax.

National 32032 was closer.

> De plichten van een docent zijn divers,         John Cowan
> die van het gehoor ook.                         cowan at ccil.org
>       --Edsger Dijkstra                         http://www.ccil.org/~cowan

Much thanks for a .sig that is in Dutch, brings back some memories.
-- 
---
Larry McVoy                lm at bitmover.com           http://www.bitkeeper.com

[TUHS] Need a new PDP-11 or VAX?

[Larry McVoy]

The 68020 came close.

On Sun, Apr 28, 2013 at 01:38:47PM +1000, Nick Downing wrote:
> I think the 68K came fairly close to what you guys are asking for, with its
> addressing modes like (a0)+ and so on. it's only 32 bit but that's better
> than 16 bit :) the problem I have with 68K is that while the assembly
> language is basically orthogonal the machine code is not, there are too
> many exceptions in the encoding, which I think was done to save precious
> code space. (Kind of like ARM Thumb code -- and by the way you may find ARM
> more PDP11-like than the other archs you mentioned). Anyway, some of the
> latest 68K such as Dragonball(?) have gone some way towards correcting this
> deficiency by not implementing many of the more irregular insns.
> cheers, Nick
> On Apr 28, 2013 12:00 PM, "John Cowan" <cowan at mercury.ccil.org> wrote:
> 
> > Larry McVoy scripsit:
> >
> > > What I'd like is a new 64 bit PDP-11.
> >
> > With a 16-bit instruction stream still, or with wider instructions and
> > more registers, almost but not quite entirely unlike the Vax?
> >
> > --
> > De plichten van een docent zijn divers,         John Cowan
> > die van het gehoor ook.                         cowan at ccil.org
> >       --Edsger Dijkstra                         http://www.ccil.org/~cowan
> > _______________________________________________
> > TUHS mailing list
> > TUHS at minnie.tuhs.org
> > https://minnie.tuhs.org/mailman/listinfo/tuhs
> >

> _______________________________________________
> TUHS mailing list
> TUHS at minnie.tuhs.org
> https://minnie.tuhs.org/mailman/listinfo/tuhs


-- 
---
Larry McVoy                lm at bitmover.com           http://www.bitkeeper.com

[TUHS] Need a new PDP-11 or VAX?

[Nick Downing]

I think the 68K came fairly close to what you guys are asking for, with its
addressing modes like (a0)+ and so on. it's only 32 bit but that's better
than 16 bit :) the problem I have with 68K is that while the assembly
language is basically orthogonal the machine code is not, there are too
many exceptions in the encoding, which I think was done to save precious
code space. (Kind of like ARM Thumb code -- and by the way you may find ARM
more PDP11-like than the other archs you mentioned). Anyway, some of the
latest 68K such as Dragonball(?) have gone some way towards correcting this
deficiency by not implementing many of the more irregular insns.
cheers, Nick
On Apr 28, 2013 12:00 PM, "John Cowan" <cowan at mercury.ccil.org> wrote:

> Larry McVoy scripsit:
>
> > What I'd like is a new 64 bit PDP-11.
>
> With a 16-bit instruction stream still, or with wider instructions and
> more registers, almost but not quite entirely unlike the Vax?
>
> --
> De plichten van een docent zijn divers,         John Cowan
> die van het gehoor ook.                         cowan at ccil.org
>       --Edsger Dijkstra                         http://www.ccil.org/~cowan
> _______________________________________________
> TUHS mailing list
> TUHS at minnie.tuhs.org
> https://minnie.tuhs.org/mailman/listinfo/tuhs
>
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[TUHS] Need a new PDP-11 or VAX?

[John Cowan]

Larry McVoy scripsit:

> What I'd like is a new 64 bit PDP-11.  

With a 16-bit instruction stream still, or with wider instructions and
more registers, almost but not quite entirely unlike the Vax?

-- 
De plichten van een docent zijn divers,         John Cowan
die van het gehoor ook.                         cowan at ccil.org
      --Edsger Dijkstra                         http://www.ccil.org/~cowan

[TUHS] Need a new PDP-11 or VAX?

[Ronald Natalie]

On Apr 27, 2013, at 5:26 PM, Dave Horsfall <dave at horsfall.org> wrote:

> http://blog.dynamoo.com/2013/04/need-new-pdp-11-or-vax.html

That brings to mind "Ron's rule of computing."   Back when 780's were the bomb, one of the managers told me that soon they would have a computer the performance of the 780 that would sit on a desktop and they'd give me one for myself and I'd be happy.     I told them, no, my expectations would also increase.

Ron's rule of computing:    I need a computer this (holding my arms out about as wide as the 780 CPU cabinet) big.

[TUHS] Need a new PDP-11 or VAX?

[Ronald Natalie]

On Apr 27, 2013, at 6:41 PM, Larry McVoy <lm at bitmover.com> wrote:

> What I'd like is a new 64 bit PDP-11.  That assembler was wonderful to
> read and write, only a short distance from C.  x86 makes me puke.  MIPS
> and Alpha aren't much better (I was hoping for better from Alpha but they
> seemed like they copied MIPS).

Or more properly the SPIM, as DEC ran both the Alpha and the MIPS in the LSB first mode.

[TUHS] Need a new PDP-11 or VAX?

[Dave Horsfall]

[ Yeah, I realised I was unsubscribed when my provider went gaga ]

On Sat, 27 Apr 2013, Larry McVoy wrote:

> What I'd like is a new 64 bit PDP-11.  That assembler was wonderful to
> read and write, only a short distance from C.

Sounds like the same concept as PL/360 (not to be confused with APL\360).

> x86 makes me puke.

x86 should've been drowned at birth.

> MIPS
> and Alpha aren't much better (I was hoping for better from Alpha but they
> seemed like they copied MIPS).

I believe you're right.

-- Dave

[TUHS] Need a new PDP-11 or VAX?

[Larry McVoy]

What I'd like is a new 64 bit PDP-11.  That assembler was wonderful to
read and write, only a short distance from C.  x86 makes me puke.  MIPS
and Alpha aren't much better (I was hoping for better from Alpha but they
seemed like they copied MIPS).

On Sun, Apr 28, 2013 at 07:26:43AM +1000, Dave Horsfall wrote:
> http://blog.dynamoo.com/2013/04/need-new-pdp-11-or-vax.html
> 
> -- Dave
> _______________________________________________
> TUHS mailing list
> TUHS at minnie.tuhs.org
> https://minnie.tuhs.org/mailman/listinfo/tuhs

-- 
---
Larry McVoy                lm at bitmover.com           http://www.bitkeeper.com

[TUHS] Need a new PDP-11 or VAX?

[Dave Horsfall]

http://blog.dynamoo.com/2013/04/need-new-pdp-11-or-vax.html

-- Dave