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

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

[Dave Horsfall]

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

-- 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]

[ 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?

[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?

[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?

[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?

[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?

[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?

[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] curmudgeon credit

[Aharon Robbins]

> 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.

True.

> x86 makes me puke.  MIPS and Alpha aren't much better

Dunno if this is the right forum, but I have to wonder about the fact
that many old-time Unix and Plan 9 folks rant and rave about different
architectures.  (I mean, I know people who are *still* pining for the
DEC-10 with TOPS-10 and TOPS-20.)

IF you are not writing the compiler or the low level OS routines, what
freaking difference does it make?  I've been doing C, Unix, C++, Linux,
etc., for over 30 years, and what matters to me more are things like
what facilities are in my C library, how standards compliant a system is,
whether the library and OS behave like they should (cf MirBSD, which is
brain dead on at least 2 counts), and so on.

The only assembly language I ever learned was the PDP-11, and that was
on a Univac system using an assembler and simulator written in Algol-W
circa 1979.   And I agree, the architecture was beautiful.

But even though my home systems and much of my work has been on x86 Linux
for close to 20 years, I don't find myself constantly moaning and groaning
that the underlying instruction set isn't clean and elegant.

So other than the curmudgeon credit, what am I missing?

Arnold

[TUHS] curmudgeon credit

[Nick Downing]

Well, I don't like wasted silicon, and although granted the price of x86
cpu's is set more by the market than the manufacturing cost, today's cpu's
are essentially recompiling the code from an archaic cisc instruction set
with 8 (x86) or 16 (amd64) registers and riddled with exceptions, to a vliw
type risc instruction set with many more registers, and doing it on the fly
with all the disadvantages that that involves such as not knowing what is
ahead in the instruction stream until it happens so that nearly everything
is speculative, dealing with restartable instructions, etc, etc... when a
compiler which knows the difference between code and data, and can perform
reasonable static analysis, could do so much of a better job... granted (1)
vliw is a waste of space, but for applications where that matters you can
just code in java and run on a hotspot vm and (2) certain runtime
information is available to the on-the-fly x86 translator that improves
performance and can't be derived by static analysis, but this can be
gathered by profiling and fed to the optimizing compiler. so to sum up, in
my opinion there is a need for a highly orthogonal risc-like isa to free up
lots of silicon to be used for extra math units etc, and/or save cpu cost
by moving functionality from hardware to software, improve reliability and
shorten cpu design cycles (because extra complexity = more potential for
bugs). one other point that remains to be mentioned is that the x86 isa
acts like an abstraction layer that gives chip designers the freedom to
radically change the chip internals without breaking compatibility and this
is a Very Good Thing, hence i propose that the mentioned vliw risc
orthogonal isa not be set in stone, i.e. bitfields are assigned or deleted,
to control whatever functional units, registers, buses etc are present in
each release of the chip, so any binary releases of software packages would
have to be in an intermediate format such as llvm or similar. (java
bytecode is maybe too high level for stuff like linux kernel, etc). just my
2c worth :)
cheers, Mixk
On Apr 28, 2013 4:33 PM, "Aharon Robbins" <arnold at skeeve.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.
>
> True.
>
> > x86 makes me puke.  MIPS and Alpha aren't much better
>
> Dunno if this is the right forum, but I have to wonder about the fact
> that many old-time Unix and Plan 9 folks rant and rave about different
> architectures.  (I mean, I know people who are *still* pining for the
> DEC-10 with TOPS-10 and TOPS-20.)
>
> IF you are not writing the compiler or the low level OS routines, what
> freaking difference does it make?  I've been doing C, Unix, C++, Linux,
> etc., for over 30 years, and what matters to me more are things like
> what facilities are in my C library, how standards compliant a system is,
> whether the library and OS behave like they should (cf MirBSD, which is
> brain dead on at least 2 counts), and so on.
>
> The only assembly language I ever learned was the PDP-11, and that was
> on a Univac system using an assembler and simulator written in Algol-W
> circa 1979.   And I agree, the architecture was beautiful.
>
> But even though my home systems and much of my work has been on x86 Linux
> for close to 20 years, I don't find myself constantly moaning and groaning
> that the underlying instruction set isn't clean and elegant.
>
> So other than the curmudgeon credit, what am I missing?
>
> Arnold
> _______________________________________________
> TUHS mailing list
> TUHS at minnie.tuhs.org
> https://minnie.tuhs.org/mailman/listinfo/tuhs
>
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[TUHS] curmudgeon credit

[Aaron J. Grier]

On Sun, Apr 28, 2013 at 05:08:28PM +1000, Nick Downing wrote:
> Well, I don't like wasted silicon

obviously not speaking for my employer here, but my understanding is
that you can't power up all the existing real-estate on modern silicon
and still meet power envelopes.  the extra silicon isn't wasted: it
merely functions as a heat-sink when it's not being utilized.  :)

are there any synthesizable (hardware description language) versions of
PDP or VAX available?  seems like hybrid FPGA / SW emulation platforms
would be an interesting experimentation space.

-- 
  Aaron J. Grier | "Not your ordinary poofy goof." | agrier at poofygoof.com

[TUHS] curmudgeon credit

[emu]

Quoting "Aaron J. Grier" <agrier at poofygoof.com>:

> are there any synthesizable (hardware description language) versions of
> PDP or VAX available?  seems like hybrid FPGA / SW emulation platforms
> would be an interesting experimentation space.

Few PDP11s (VHDL?) are out there, no VAX in the wild as far as I know ...

[TUHS] curmudgeon credit

[David Evans]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain, Size: 763 bytes --]

On 14 May 2013, at 07:52, emu at e-bbes.com wrote:

> Quoting "Aaron J. Grier" <agrier at poofygoof.com>:
> 
>> are there any synthesizable (hardware description language) versions of
>> PDP or VAX available?  seems like hybrid FPGA / SW emulation platforms
>> would be an interesting experimentation space.
> 
> Few PDP11s (VHDL?) are out there, no VAX in the wild as far as I know …
> 

Yes; I've run 7th Edition on

http://pdp2011.sytse.net/wordpress/

Was too lazy to get 2.11BSD working and I see that it has progressed a lot in the year since I tried it. I think I played with

http://opencores.org/project,w11

too but I can't remember what I did.

I've spent most time with an -8 and there are a couple of -10s out there but then that's not Unix...

[TUHS] curmudgeon credit

[Larry McVoy]

On Sun, Apr 28, 2013 at 08:34:53AM +0300, Aharon Robbins 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.
> 
> True.

> IF you are not writing the compiler or the low level OS routines, what
> freaking difference does it make?  

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 expect the world to suddenly sit up and decide that it is important
to do what I want and give me my 64 bit PDP-11, but if that happened I'd
cheer :)

I think part of it is a yearning for simpler times.  That architecture 
was just so pleasant, you could move quite easily from C to assembler
and back again.  If I had to teach CS these days I'd prefer that 
assembler (but actually using it would be a disservice to the kids,
you want them to know x86 or ARM at this point).
-- 
---
Larry McVoy                lm at bitmover.com           http://www.bitkeeper.com

[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?

[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?

[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?

[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.