Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Eric Smith 
On Mon, Jul 1, 2019 at 3:10 PM Seth J. Morabito  wrote:

> An interesting question! It's true that none of the simulators currently
> do microcode simulation, but I don't see why they couldn't. Certain
> assumptions about clock calibration may be in question, but I'm not
> sure. Even if they were, I think it's a surmountable problem and not
> fundamentally impossible given SIMH's architecture.


I've done microcode level simulation of various systems including four
generations of HP calculators.

I've done some work toward microcode level simulation of the LSI-11,
Western Digital WD16, and Western Digital Pascal Microengine, all of which
use the same chipset with different microcode and macroinstruction decode
PLAs.  I got to the point where the Pascal Microengine can successfully
execute the first few p-code instructions of a boot ROM. (Note that the
most common versions of the WD Pascal Microengine don't actually have a
boot ROM.)

While I have dumped the microcode for the LSI-11, WD16, and multiple
microcode releases of the Pascal Microengine, I have only completed
transcription from photomicrographs of the PLAs of the Pascal Microengine.
The PLAs of the LSI-11 and WD16 still need to be transcribed.

A partially reverse-engineered disassembly of the LSI-11 microcode is in
this github repo:
https://github.com/brouhaha/lsi11uc
Without the transcribed PLAs, it isn't complete or useful.

Best regards,
Eric
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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Paul Koning 


> On Jul 1, 2019, at 5:09 PM, Seth J. Morabito  wrote:
> 
> 
> Lars Brinkhoff writes:
> 
>> Bob Supnik wrote:
>>> The J-11 based simulators (11/73 and up) are the only ones that were
>>> verified against actual machine microcode.
>> 
>> Speaking of which.  Someone claimed SIMH wouldn't be well suited for a
>> microcode level simulation.  Is there any truth to this?  If so why?
> 
> An interesting question! It's true that none of the simulators currently
> do microcode simulation, but I don't see why they couldn't. Certain
> assumptions about clock calibration may be in question, but I'm not
> sure. Even if they were, I think it's a surmountable problem and not
> fundamentally impossible given SIMH's architecture.

I can see no theoretical issues, but a number of practical ones.

("In theory, there is no difference between theory and practice. But, in 
practice, there is." -- Jan L.A. van de Snepscheut)

The programmer ISA is usually well documented, minimally in programmer's 
manuals and sometimes in formal standards.  The micro-architecture is 
documented in internal design specs that often have not survived and may not 
have been updated to reflect the actual design as shipped.  

Schematics and ROM contents, if accurate, may help but are not sufficient if 
parts of the micro-architecture are buried inside chips whose internals are not 
exposed in those documents.

Micro-architectures typically are done separately for each product, so a given 
family (like PDP-11 or VAX) might have a dozen vastly different ones.

Micro-programs are often very wide and directly manipulate many low level 
controls.  So a micro-architecture simulator would be a whole lot more 
complicated than the ISA simulator (and as a consequence much slower).

If the micro-architecture simulation is accurate, it would give an accurate ISA 
simulation.  But then again, if it's possible to build an accurate simulation 
one might as well put the effort into making the ISA simulation accurate.

---
An analogous case comes to mind.  It's possible (and has been done) to build a 
VHDL model of a PDP-11.  That's a separate design, just as SIMH is, and both 
may have discrepancies from the original hardware.  If you have enough detail 
you could build a VHDL model of the original design, which might be interesting 
-- for example, it would allow you to explore undocumented aspects of the 
machine operation.

I've actually done this (in part, the work is not nearly complete) for the CDC 
6600.  For that machine, full transistor-level schematics exist, so a gate 
level accurate VHDL model would seem to be possible.  It's actually 
surprisingly hard mostly because in that machine timing is on the hairy edge of 
not working -- you must simulate the gate delays to come even close, and some 
of the wire delays.  If you do so then easy parts like the peripheral 
processors work, but harder parts like the instruction scheduling machinery are 
so "on the edge" that they stubbornly refuse to work.

I suppose translating, say, PDP-11/20 or EL-X8 schematics to gate level VHDL 
models would be possible.  Whether anyone would find it worth the trouble is 
another question.

paul



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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Seth J. Morabito 

Lars Brinkhoff writes:

> Bob Supnik wrote:
>> The J-11 based simulators (11/73 and up) are the only ones that were
>> verified against actual machine microcode.
>
> Speaking of which.  Someone claimed SIMH wouldn't be well suited for a
> microcode level simulation.  Is there any truth to this?  If so why?

An interesting question! It's true that none of the simulators currently
do microcode simulation, but I don't see why they couldn't. Certain
assumptions about clock calibration may be in question, but I'm not
sure. Even if they were, I think it's a surmountable problem and not
fundamentally impossible given SIMH's architecture.

-Seth
--
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  Poulsbo, WA, USA
  w...@loomcom.com
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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Arthur Krewat 
If anyone is interested, I MIGHT have an SMD controller from a 
Vax-11/750 - it would be UNIBUS.


I also have a pair of 9" SMD drives from a Sun 3 - but not sure I want 
to part with them. They would have to be wiped first anyway - they have 
defense contractor stuff on them :)



On 7/1/2019 2:27 PM, Ethan Dicks wrote:

On Mon, Jul 1, 2019 at 1:14 PM Johnny Billquist  wrote:

If we talk about running actual hardware, then you can run SCSI on
Unibus systems as well

I would love to have a Unibus SCSI controller but I haven't seen any
under $500.  I have UDA50s, since those are abundant, and RL11s but
that's about it for Unibus hard disk controllers.  I'm sad I had to
leave a pair of clean and working RK07s behind in 1993 but there was
just no room for them.

-ethan
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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Johnny Billquist 

On 2019-07-01 20:27, Ethan Dicks wrote:

On Mon, Jul 1, 2019 at 1:14 PM Johnny Billquist  wrote:

If we talk about running actual hardware, then you can run SCSI on
Unibus systems as well


I would love to have a Unibus SCSI controller but I haven't seen any
under $500.  I have UDA50s, since those are abundant, and RL11s but
that's about it for Unibus hard disk controllers.  I'm sad I had to
leave a pair of clean and working RK07s behind in 1993 but there was
just no room for them.


Well, I never warmed up to the RK06/07. Slow and finicky, in my experience.

But then again, I also happen to have a Unibus SCSI controller...
But yes, they are not cheap these days.

  Johnny

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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Johnny Billquist 
Just as an FYI: An RP04/05/06 is 22" wide, if we talk about the whole 
disk cabinet, and that is excluding the DCL side cabinet. The DCL added 
another 9" for a total of 31 inch. An RP07 with side covers is 26.5 inch.


  Johnny

On 2019-07-01 13:31, Clem cole wrote:
19” form factor for the disks drive fir the space in the 19” relay rack. 
  You’re right the platters themselves were smaller.  The disks were 
referred too by the mechanical FF.  19, 8, 5.25 etc.


Sent from my PDP-7 Running UNIX V0 expect things to be almost but not 
quite.


On Jul 1, 2019, at 12:07 AM, Eric Smith > wrote:


On Sun, Jun 30, 2019, 19:37 Clem cole > wrote:


You can use RH70 (massbus controllers) and just use the larger
(originally expensive) 19” disks from the early days.


14 inch, but who's counting.  :-)

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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Ethan Dicks 
On Mon, Jul 1, 2019 at 1:14 PM Johnny Billquist  wrote:
> If we talk about running actual hardware, then you can run SCSI on
> Unibus systems as well

I would love to have a Unibus SCSI controller but I haven't seen any
under $500.  I have UDA50s, since those are abundant, and RL11s but
that's about it for Unibus hard disk controllers.  I'm sad I had to
leave a pair of clean and working RK07s behind in 1993 but there was
just no room for them.

-ethan
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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Johnny Billquist 
If we talk about running actual hardware, then you can run SCSI on 
Unibus systems as well. And if we're talking simulation, you can pretty 
much run any disk size you want, if you go with MSCP.


Pretty much all SCSI controllers for PDP-11s appeared as MSCP 
controllers anyway.


  Johnny

On 2019-07-01 03:29, Clem cole wrote:

Btw.  The biggest advantage of the later model qbus systems is some larger but 
cheaper scsi options  that dec released later in life but none of that has ever 
mattered to me in practice when running simh.  You can use RH70 (massbus 
controllers) and just use the larger (originally expensive) 19” disks from the 
early days.

Sent from my PDP-7 Running UNIX V0 expect things to be almost but not quite.


On Jun 30, 2019, at 8:52 PM, Will Senn  wrote:

All,

Is there any particular reason to choose one model of PDP-11 over another in 
the sim? I am a user who is usually only interested in using one of the various 
programming languages available on the dec oses - I frequently use RT-11 for 
BASIC or ASSEMBLY and Unix V6 and V7 for C and for fun, as well as an 
occasional foray into RSTS-E and lately RSX 11-M Plus to try and find the 
perfect OS for as many programming languages as I can get in one place. In my 
language/os explorations, I generally just grab somebody's example ini file or 
take a default machine 11/40 or 11/94, but it's been pretty will-nilly on my 
part. I'd like to have some kind of rationale related to necessity, but it 
doesn't really seem to make much difference. I know the 11/45 had split I/D, 
making it 'better' than the 11/40 and that the unibus is different than the 
q-bus and I'm sure the hardware support is different between the models, but I 
haven't really been prevented from running anything that is runnable... but of 
course, if I was prevented, I just chalked it up to who knows why that didn't 
work, so I might never know if I'm missing out on the El Dorado of ancient 
OSes. Does anyone have some guidelines to help choose which model configuration 
is appropriate for various needs? Or, in this day and age of endless supplies 
of ram and memory, should I just load it up to the biggest, baddest, pdp-11 of 
all time and leave it at that (and if so, which one is that?).

Thanks for the assist.

Regards,

Will

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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Eric Smith 
On Mon, Jul 1, 2019 at 5:31 AM Clem cole  wrote:

> 19” form factor for the disks drive fir the space in the 19” relay rack.
> You’re right the platters themselves were smaller.  The disks were referred
> too by the mechanical FF.  19, 8, 5.25 etc.
>

The DEC RP and RM drives were not rack-mount, and the drives were much
wider than 19-inch.
The entire industry referred to disk size in terms of the platter diameter,
which went from 14 to 8 to 5.25 to 3.5 to 2.5 inches. The drives were
always wider than the stated platter diameter.
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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Eric Smith 
On Mon, Jul 1, 2019 at 10:00 AM Lars Brinkhoff  wrote:

> Speaking of which.  Someone claimed SIMH wouldn't be well suited for a
> microcode level simulation.  Is there any truth to this?  If so why?
>

I haven't dug into the SIMH code all that much, but there's no obvious
reason that SIMH can't simulate a microcode engine.

IIRC Bob has written that no one has succeeded at building an alternate J11
hardware implementation, e.g., in an FPGA., because the microcode is not
entirely ROM. There is a fairly large (for the time) PLA forming part of
the control store. The PLA could be transformed into a ROM, but IIRC it has
_many_ inputs, so the ROM would be YUGE.

Almost 20 years ago I wrote a program to translate the PLA into VHDL
directly instantiating Xilinx 4LUT primitives to see how much resources it
would consume in e.g. a Spartan 3 FPGA. I don't recall the numbers, but it
didn't seem insurmountable at the time, and with today's bigger FPGAs and
6LUTs, it's even less of a problem.

Also, I think the synthesis tools are good enough that just giving the PLA
equations to synthesis would be fine, and my scheme of programmatically
transforming the equations to LUT instantiations is totally unnecessary.

Eric
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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Will Senn 

On 7/1/19 9:48 AM, Bob Supnik wrote:

If I may interject a serious note...

The J-11 based simulators (11/73 and up) are the only ones that were 
verified against actual machine microcode. The 11/73 system was the 
only one verified against its board and system specification. The 
others are all derivatives.


I always debug with the 11/73. It has 4M memory, I/D space, and access 
to large disks via the MSCP controller.


/Bob

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Thank you, Bob! I'll take this as canonical and run with it :).

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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Lars Brinkhoff 
Bob Supnik wrote:
> The J-11 based simulators (11/73 and up) are the only ones that were
> verified against actual machine microcode.

Speaking of which.  Someone claimed SIMH wouldn't be well suited for a
microcode level simulation.  Is there any truth to this?  If so why?

Asking for a friend.

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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Bob Supnik 

If I may interject a serious note...

The J-11 based simulators (11/73 and up) are the only ones that were 
verified against actual machine microcode. The 11/73 system was the only 
one verified against its board and system specification. The others are 
all derivatives.


I always debug with the 11/73. It has 4M memory, I/D space, and access 
to large disks via the MSCP controller.


/Bob

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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Tim Wilkinson 
Back in 85 have had applications to purchase a 785 – 780-750-730 then 725 
rejected, we were fortunately given a 750 by a sister company who were 
upgrading to a 785, but they took their disks. So we had to buy for ourselves.



To keep the bean counter happy we went for a System Industries controller and 4 
super Eagles.



But back then there was a problem with the eagles and all 4 had to be swapped 
out 4 times.



Carrying them up stairs to the computer room was not fun. The platter size may 
have been reduced. But the weight!!!



Tim

From: Simh [mailto:simh-boun...@trailing-edge.com] On Behalf Of Clem Cole
Sent: 01 July 2019 14:08
To: Patrick Finnegan 
Cc: SIMH 
Subject: Re: [Simh] Which PDP-11 to choose



I can not say why it followed that naming convention, but it did.   The drives 
of that day were referred to as 19" technology since that's how they mounted.   
FWIW:   Most manufacturers at the time used the same platter size as the 
original IBM 1311 (which as you pointed out was 14"), but not everyone, for 
instance, the Fujitsu Eagle used 10.5-inch platter.   FWIW:  I answered a bunch 
of this in: 
https://www.quora.com/How-do-hard-drives-get-smaller-and-smaller-in-size-bigger-and-bigger-in-capacity-every-year-when-the-fundamental-physical-processes-behind-them-do-not-change/answer/Clem-Cole



On Mon, Jul 1, 2019 at 8:52 AM Patrick Finnegan mailto:p...@computer-refuge.org> > wrote:





On Mon, Jul 1, 2019 at 7:32 AM Clem cole mailto:cl...@ccc.com> 
> wrote:

19” form factor for the disks drive fir the space in the 19” relay rack.  
You’re right the platters themselves were smaller.  The disks were referred too 
by the mechanical FF.  19, 8, 5.25 etc.



But, 8" hard drives have 8" platters, and 5.25" hard drives have 5.25" 
platters. The casing on a the 5.25" drive in front of me is almost 6" wide.



Pat



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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Clem Cole 
I can not say why it followed that naming convention, but it did.   The
drives of that day were referred to as 19" technology since that's how they
mounted.   FWIW:   Most manufacturers at the time used the same platter
size as the original IBM 1311 (which as you pointed out was 14"), but not
everyone, for instance, the Fujitsu Eagle used 10.5-inch platter.   FWIW:
I answered a bunch of this in:
https://www.quora.com/How-do-hard-drives-get-smaller-and-smaller-in-size-bigger-and-bigger-in-capacity-every-year-when-the-fundamental-physical-processes-behind-them-do-not-change/answer/Clem-Cole


On Mon, Jul 1, 2019 at 8:52 AM Patrick Finnegan 
wrote:

>
>
> On Mon, Jul 1, 2019 at 7:32 AM Clem cole  wrote:
>
>> 19” form factor for the disks drive fir the space in the 19” relay rack.
>> You’re right the platters themselves were smaller.  The disks were referred
>> too by the mechanical FF.  19, 8, 5.25 etc.
>>
>>
> But, 8" hard drives have 8" platters, and 5.25" hard drives have 5.25"
> platters. The casing on a the 5.25" drive in front of me is almost 6" wide.
>
> Pat
>
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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Patrick Finnegan 
On Mon, Jul 1, 2019 at 7:32 AM Clem cole  wrote:

> 19” form factor for the disks drive fir the space in the 19” relay rack.
> You’re right the platters themselves were smaller.  The disks were referred
> too by the mechanical FF.  19, 8, 5.25 etc.
>
>
But, 8" hard drives have 8" platters, and 5.25" hard drives have 5.25"
platters. The casing on a the 5.25" drive in front of me is almost 6" wide.

Pat
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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Clem cole 
19” form factor for the disks drive fir the space in the 19” relay rack.  
You’re right the platters themselves were smaller.  The disks were referred too 
by the mechanical FF.  19, 8, 5.25 etc.   

Sent from my PDP-7 Running UNIX V0 expect things to be almost but not quite. 

> On Jul 1, 2019, at 12:07 AM, Eric Smith  wrote:
> 
>> On Sun, Jun 30, 2019, 19:37 Clem cole  wrote:
>> You can use RH70 (massbus controllers) and just use the larger (originally 
>> expensive) 19” disks from the early days. 
> 
> 
> 14 inch, but who's counting.  :-)
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Re: [Simh] Which PDP-11 to choose

2019-07-01 Thread Johnny Billquist 

On 2019-07-01 06:07, Eric Smith wrote:
On Sun, Jun 30, 2019, 19:37 Clem cole > wrote:


You can use RH70 (massbus controllers) and just use the larger
(originally expensive) 19” disks from the early days.


14 inch, but who's counting.  :-)


Also, even the largest massbus disks weren't that large. And the RP07, 
being the largest, was not really supported that well on the PDP-11. In 
reality you could only run it on an 11/70, and at roughly half a gig, 
it's rather small today.


MSCP disks have the advantage of being able to be arbitrary size, and 
can be very big, and are supported by all models.


Also, speaking of models, I would usually recommend something with 
22-bit addressing and split I/D space. So no 11/40. 11/70 would be my 
choice for a Unibus machine, and 11/93 for a Qbus.
The slight advantage of an 11/93 is the TOY clock. Otherwise it's the 
same as the 11/73 and 11/83.


11/94 is also an option if you want to pretend Unibus, and it can take a 
little bit more ram than an 11/70.


So, large machine, and then put in 4M of memory (more or less, depending 
on model), a couple of really big MSCP disks, and off you go.


  Johnny

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Re: [Simh] Which PDP-11 to choose

2019-06-30 Thread Eric Smith 
On Sun, Jun 30, 2019, 19:37 Clem cole  wrote:

> You can use RH70 (massbus controllers) and just use the larger (originally
> expensive) 19” disks from the early days.
>

14 inch, but who's counting.  :-)

>
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Re: [Simh] Which PDP-11 to choose

2019-06-30 Thread Clem cole 
Btw.  The biggest advantage of the later model qbus systems is some larger but 
cheaper scsi options  that dec released later in life but none of that has ever 
mattered to me in practice when running simh.  You can use RH70 (massbus 
controllers) and just use the larger (originally expensive) 19” disks from the 
early days. 

Sent from my PDP-7 Running UNIX V0 expect things to be almost but not quite. 

> On Jun 30, 2019, at 8:52 PM, Will Senn  wrote:
> 
> All,
> 
> Is there any particular reason to choose one model of PDP-11 over another in 
> the sim? I am a user who is usually only interested in using one of the 
> various programming languages available on the dec oses - I frequently use 
> RT-11 for BASIC or ASSEMBLY and Unix V6 and V7 for C and for fun, as well as 
> an occasional foray into RSTS-E and lately RSX 11-M Plus to try and find the 
> perfect OS for as many programming languages as I can get in one place. In my 
> language/os explorations, I generally just grab somebody's example ini file 
> or take a default machine 11/40 or 11/94, but it's been pretty will-nilly on 
> my part. I'd like to have some kind of rationale related to necessity, but it 
> doesn't really seem to make much difference. I know the 11/45 had split I/D, 
> making it 'better' than the 11/40 and that the unibus is different than the 
> q-bus and I'm sure the hardware support is different between the models, but 
> I haven't really been prevented from running anything that is runnable... but 
> of course, if I was prevented, I just chalked it up to who knows why that 
> didn't work, so I might never know if I'm missing out on the El Dorado of 
> ancient OSes. Does anyone have some guidelines to help choose which model 
> configuration is appropriate for various needs? Or, in this day and age of 
> endless supplies of ram and memory, should I just load it up to the biggest, 
> baddest, pdp-11 of all time and leave it at that (and if so, which one is 
> that?).
> 
> Thanks for the assist.
> 
> Regards,
> 
> Will
> 
> -- 
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Re: [Simh] Which PDP-11 to choose

2019-06-30 Thread Clem cole 
IMO if you want to program the system split ID is helpful as 64k is very small. 
 Thus the 11/70 or 11/44 are my go to systems.  Your call.  

Sent from my PDP-7 Running UNIX V0 expect things to be almost but not quite. 

> On Jun 30, 2019, at 8:52 PM, Will Senn  wrote:
> 
> All,
> 
> Is there any particular reason to choose one model of PDP-11 over another in 
> the sim? I am a user who is usually only interested in using one of the 
> various programming languages available on the dec oses - I frequently use 
> RT-11 for BASIC or ASSEMBLY and Unix V6 and V7 for C and for fun, as well as 
> an occasional foray into RSTS-E and lately RSX 11-M Plus to try and find the 
> perfect OS for as many programming languages as I can get in one place. In my 
> language/os explorations, I generally just grab somebody's example ini file 
> or take a default machine 11/40 or 11/94, but it's been pretty will-nilly on 
> my part. I'd like to have some kind of rationale related to necessity, but it 
> doesn't really seem to make much difference. I know the 11/45 had split I/D, 
> making it 'better' than the 11/40 and that the unibus is different than the 
> q-bus and I'm sure the hardware support is different between the models, but 
> I haven't really been prevented from running anything that is runnable... but 
> of course, if I was prevented, I just chalked it up to who knows why that 
> didn't work, so I might never know if I'm missing out on the El Dorado of 
> ancient OSes. Does anyone have some guidelines to help choose which model 
> configuration is appropriate for various needs? Or, in this day and age of 
> endless supplies of ram and memory, should I just load it up to the biggest, 
> baddest, pdp-11 of all time and leave it at that (and if so, which one is 
> that?).
> 
> Thanks for the assist.
> 
> Regards,
> 
> Will
> 
> -- 
> GPG Fingerprint: 68F4 B3BD 1730 555A 4462  7D45 3EAA 5B6D A982 BAAF
> 
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[Simh] Which PDP-11 to choose

2019-06-30 Thread Will Senn 

All,

Is there any particular reason to choose one model of PDP-11 over 
another in the sim? I am a user who is usually only interested in using 
one of the various programming languages available on the dec oses - I 
frequently use RT-11 for BASIC or ASSEMBLY and Unix V6 and V7 for C and 
for fun, as well as an occasional foray into RSTS-E and lately RSX 11-M 
Plus to try and find the perfect OS for as many programming languages as 
I can get in one place. In my language/os explorations, I generally just 
grab somebody's example ini file or take a default machine 11/40 or 
11/94, but it's been pretty will-nilly on my part. I'd like to have some 
kind of rationale related to necessity, but it doesn't really seem to 
make much difference. I know the 11/45 had split I/D, making it 'better' 
than the 11/40 and that the unibus is different than the q-bus and I'm 
sure the hardware support is different between the models, but I haven't 
really been prevented from running anything that is runnable... but of 
course, if I was prevented, I just chalked it up to who knows why that 
didn't work, so I might never know if I'm missing out on the El Dorado 
of ancient OSes. Does anyone have some guidelines to help choose which 
model configuration is appropriate for various needs? Or, in this day 
and age of endless supplies of ram and memory, should I just load it up 
to the biggest, baddest, pdp-11 of all time and leave it at that (and if 
so, which one is that?).


Thanks for the assist.

Regards,

Will

--
GPG Fingerprint: 68F4 B3BD 1730 555A 4462  7D45 3EAA 5B6D A982 BAAF

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