Re: PDP-11/70 Boards

[Tony Duell via cctalk]

On Thu, Dec 9, 2021 at 12:26 PM Rob Jarratt  wrote:
>
> Hello Tony,
>
> > The power bricks draw very little current with no load on the output and 
> > 2.5A
> > would be fine to power one up.
>
>
> Are you saying that I can test them with no load? I thought they would need 
> some load?

I'm pretty sure I've run them with no load and they have been fine.
Note that the regulation is not that good, the voltage may be a little
high with no load, and if you tweak it down with the preset you'll
have to turn it up again when you run the PDP11 off said bricks.

Also note that they are switching regulators. As a result, 2.5A input
current at say 20V would give a good few amps (10A if they were 100%
efficient, more like 8A in practice I would guess) at the output.

-tony

RE: PDP-11/70 Boards

[Rob Jarratt via cctalk]

Hello Tony,

> The power bricks draw very little current with no load on the output and 2.5A
> would be fine to power one up.


Are you saying that I can test them with no load? I thought they would need 
some load?


> 
> Most, if not all, of the  power bricks start by rectifying and smoothing the 
> AC
> input. As a result they will run off a DC input too.
> You can test them using a bench supply,  normally do.
> 
> One final thing. Do not, (as I did when younger and even more foolish)
> disable the over-current trip in a power brick. If the crowbar operates, you
> will end up with transistors blown off the PCB.
> 
> 
> -tony

Re: PDP-11/70 Boards

[Tony Duell via cctalk]

On Wed, Dec 8, 2021 at 9:58 PM Rob Jarratt via cctalk
 wrote:

> > I have a variac rated at 2.5A. I am not quite sure whether that would be
> > sufficient to test the bricks individually. Otherwise, I guess one of these
> > would do the trick https://cpc.farnell.com/block/steu250-48/transformer-
> > 250va-230-400v-2-x/dp/TF01418?st=24v%20transformer ?
>
> So, to supply the bricks on the bench, would a variac rated at 2.5A be OK? I 
> am not sure I know how much current the bricks will draw at 20VAC, and at 
> what voltage the 2.5A rating is given. Otherwise, would this do the trick? 
> https://cpc.farnell.com/block/steu250-48/transformer-250va-230-400v-2-x/dp/TF01418?st=24v%20transformer

Most Variacs do not provide isolation between the input and output,
that is they are variable _autotransformers_. So if you use one to
test a power brick, the latter is directly connected to the mains
supply. Connecting an earthed 'scope to any point in said power brick
will then blow fuses at least. Touching any point in the power brick
could give you a nasty shock.

The power bricks draw very little current with no load on the output
and 2.5A would be fine to power one up.

Most, if not all, of the  power bricks start by rectifying and
smoothing the AC input. As a result they will run off a DC input too.
You can test them using a bench supply,  normally do.

One final thing. Do not, (as I did when younger and even more foolish)
disable the over-current trip in a power brick. If the crowbar
operates, you will end up with transistors blown off the PCB.


-tony

RE: PDP-11/70 Boards

[Will Cooke via cctalk]

> On 12/08/2021 5:14 PM Rob Jarratt  wrote:


> 
> 
> The problem is that it isn't marked with a wattage, just a current, which 
> left me wondering at what voltage. Although Will Cooke's response seems to be 
> that the voltage doesn't matter, so at 240VAC it would be 600W. Can that be 
> right?


My previous response was a bit misleading and not completely accurate. Sorry. I 
was trying to rush out the door.


Variacs are rated for max current. In the stated case, 2.5 amps. They can 
provide that current at any output voltage. So, the maximum wattage (actually 
volts-amps, which is a bit different) will be 2.5 amps * highest output 
voltage. (Some are possibly rated at for that current when the output voltage 
does not exceed the input. They can usually go higher than the input by 20% or 
so) They can provide that same current at any voltage UP TO that max output 
voltage. In theory, they could provide higher current at lower output voltages. 
The magnetic flux is proportional to current times turns (of wire on the core.) 
A lower output voltage implies fewer turns. BUT, the rest of the transformer is 
not designed for that higher current. So it is a bad idea to try to pull more 
than the rated current. However, pulling that rated current at any output 
voltage up to the input voltage is fine.


You can get a pretty good idea how much power a variac (or any transformer) can 
handle by its weight and size. The 3 amp variable transformer I have on my 
bench weighs about 25 pounds. It is a 120V input so that is about 360 
volt-amps. One that can handle 600 volt-amps will weight around twice as much 
(the relationship isn't linear, though.)


Why do I keep saying volt-amps instead of Watts? Watts are actual power. 
Volt-amps are apparent power. If there are capacitors or inductors in the 
circuit the current and voltage will be out of phase. That phase change means 
the current and voltage won't peak at the same time and therefore the actual 
amount of power used will be less than it "appears" by multiplying volts * 
amps. But the core and winding of the tranformer will still have to handle the 
apparent power, even though the actual power used is less. The actual power 
used is the apparent power times the cosine of the angular difference in phase.


I'm not familiar with the DEC power supplies, but it is almost certain they 
have capacitor input power supplies. That means a phase change. That means, 
then, that your input supply will need to provide more apparent power than 
actual power used. A rough approximation is to double the input from what the 
supply outputs, assuming reasonable efficient supplies. So if one of those DEC 
supplies provides, say, 5 volts at 10 amps, that is 50 watts output. I would 
start with a variac (or whatever) that can supply 100 volt-amps at the input 
voltage. So, for 20V input it would need 5 amps.


Will

Re: PDP-11/70 Boards

[Mike Katz via cctalk]

That would depend on the type and size of wire (solid core, stranded, 
strands of stranded, etc.).


On 12/8/2021 5:06 PM, pbir...@gmail.com wrote:

Seems to me that the actual coil resistance will limit the max-current at lower 
voltages.  20 A through wire sized for 1 A seems ... unlikely?

-Original Message-
From: cctalk  On Behalf Of Mike Katz via cctalk
Sent: Wednesday, December 8, 2021 5:58 PM
To: General Discussion: On-Topic and Off-Topic Posts ; 
wrco...@wrcooke.net
Subject: Re: PDP-11/70 Boards

More accurately up to it's rated wattage "Power = Voltage * Current"
after all.

If you have a 100W max variac you can draw 20A @ 5V (approx) but only 1A at 
100V.

On 12/8/2021 4:44 PM, Mike Katz via cctalk wrote:

"As a general rule, a variable transformer (Variac) can provide full
rated current at any output voltage. So a 2.5A unit can provide 2.5 A
at 1V, 10V, 120V, etc. With a 20V output, that is 50 VA (Watts, sort
of)."

Up to the current rating of the variac.  When you draw more current
than the transformer can deliver then the voltage will sag.

On 12/8/2021 4:22 PM, Will Cooke via cctalk wrote:

On 12/08/2021 3:58 PM Rob Jarratt via cctalk 
wrote:
So, to supply the bricks on the bench, would a variac rated at 2.5A
be OK? I am not sure I know how much current the bricks will draw at
20VAC, and at what voltage the 2.5A rating is given. Otherwise,
would this do the trick?
https://cpc.farnell.com/block/steu250-48/transformer-250va-230-400v-
2-x/dp/TF01418?st=24v%20transformer

Thanks

Rob



JRJ

As a general rule, a variable transformer (Variac) can provide full
rated current at any output voltage.  So a 2.5A unit can provide 2.5
A at 1V, 10V, 120V, etc.  With a 20V output, that is 50 VA (Watts,
sort of).

Will

"I was born not knowing and have had only a little time to change
that here and there."
Richard Feynman

RE: PDP-11/70 Boards

[Rob Jarratt via cctalk]

> -Original Message-
> From: cctalk  On Behalf Of Mike Katz via
> cctalk
> Sent: 08 December 2021 22:58
> To: General Discussion: On-Topic and Off-Topic Posts
> ; wrco...@wrcooke.net
> Subject: Re: PDP-11/70 Boards
> 
> More accurately up to it's rated wattage "Power = Voltage * Current"
> after all.
> 
> If you have a 100W max variac you can draw 20A @ 5V (approx) but only 1A at
> 100V.


The problem is that it isn't marked with a wattage, just a current, which left 
me wondering at what voltage. Although Will Cooke's response seems to be that 
the voltage doesn't matter, so at 240VAC it would be 600W. Can that be right?


> 
> On 12/8/2021 4:44 PM, Mike Katz via cctalk wrote:
> > "As a general rule, a variable transformer (Variac) can provide full
> > rated current at any output voltage. So a 2.5A unit can provide 2.5 A
> > at 1V, 10V, 120V, etc. With a 20V output, that is 50 VA (Watts, sort
> > of)."
> >
> > Up to the current rating of the variac.  When you draw more current
> > than the transformer can deliver then the voltage will sag.
> >
> > On 12/8/2021 4:22 PM, Will Cooke via cctalk wrote:
> >>
> >>> On 12/08/2021 3:58 PM Rob Jarratt via cctalk 
> >>> wrote:
> >>> So, to supply the bricks on the bench, would a variac rated at 2.5A
> >>> be OK? I am not sure I know how much current the bricks will draw at
> >>> 20VAC, and at what voltage the 2.5A rating is given. Otherwise,
> >>> would this do the trick?
> >>> https://cpc.farnell.com/block/steu250-48/transformer-250va-230-400v-
> >>> 2-x/dp/TF01418?st=24v%20transformer
> >>>
> >>> Thanks
> >>>
> >>> Rob
> >>>
> >>>
> >>>>> JRJ
> >> As a general rule, a variable transformer (Variac) can provide full
> >> rated current at any output voltage.  So a 2.5A unit can provide 2.5
> >> A at 1V, 10V, 120V, etc.  With a 20V output, that is 50 VA (Watts,
> >> sort of).
> >>
> >> Will
> >>
> >> "I was born not knowing and have had only a little time to change
> >> that here and there."
> >> Richard Feynman
> >

RE: PDP-11/70 Boards

[Will Cooke via cctalk]

Variable transformers (generic. Variac is a trademarked brand of them) are 
rated in amps output, not in watts or, more accurately, volt-amps. That is 
because they are rated to deliver that current at ANY voltage. The main 
limiting factor is flux density in the core. The flux density is proportional 
to the current. So, the rated current (e.g. 2.5 amps in the original question) 
can be drawn at ANY output voltage without overloading the core. At 1V out, you 
get 2.5 volt-amps. At 120V out you get 300 volt-amps. The current is the same, 
so the IR (resistive) losses of voltage are the same.

If you draw more current than the rated current, then the core will be 
overloaded. It will most likely overheat and will possibly be permanently 
damaged. In addition, the IR losses will increase, causing more overheating.

> On 12/08/2021 5:06 PM pbir...@gmail.com wrote:
> 
> 
> Seems to me that the actual coil resistance will limit the max-current at 
> lower voltages. 20 A through wire sized for 1 A seems ... unlikely?
> 
> -Original Message-
> From: cctalk  On Behalf Of Mike Katz via cctalk
> Sent: Wednesday, December 8, 2021 5:58 PM
> To: General Discussion: On-Topic and Off-Topic Posts ; 
> wrco...@wrcooke.net
> Subject: Re: PDP-11/70 Boards
> 
> More accurately up to it's rated wattage "Power = Voltage * Current"
> after all.
> 
> If you have a 100W max variac you can draw 20A @ 5V (approx) but only 1A at 
> 100V.
> 
> On 12/8/2021 4:44 PM, Mike Katz via cctalk wrote:
> > "As a general rule, a variable transformer (Variac) can provide full
> > rated current at any output voltage. So a 2.5A unit can provide 2.5 A
> > at 1V, 10V, 120V, etc. With a 20V output, that is 50 VA (Watts, sort
> > of)."
> > Up to the current rating of the variac. When you draw more current
> > than the transformer can deliver then the voltage will sag.
> > On 12/8/2021 4:22 PM, Will Cooke via cctalk wrote:
> > >
> >>> On 12/08/2021 3:58 PM Rob Jarratt via cctalk 
> >>> wrote:
> >>> So, to supply the bricks on the bench, would a variac rated at 2.5A
> >>> be OK? I am not sure I know how much current the bricks will draw at
> >>> 20VAC, and at what voltage the 2.5A rating is given. Otherwise,
> >>> would this do the trick?
> >>> https://cpc.farnell.com/block/steu250-48/transformer-250va-230-400v-
> >>> 2-x/dp/TF01418?st=24v%20transformer
> >>>
> >>> Thanks
> >>>
> >>> Rob
> >>>
> >>>
> >>>>> JRJ
> >> As a general rule, a variable transformer (Variac) can provide full
> >> rated current at any output voltage. So a 2.5A unit can provide 2.5
> >> A at 1V, 10V, 120V, etc. With a 20V output, that is 50 VA (Watts,
> >> sort of).
> >>
> >> Will
> >>
> >> "I was born not knowing and have had only a little time to change
> >> that here and there."
> >> Richard Feynman
> >

"I was born not knowing and have had only a little time to change that here and 
there."
Richard Feynman

RE: PDP-11/70 Boards

[pbirkel--- via cctalk]

Seems to me that the actual coil resistance will limit the max-current at lower 
voltages.  20 A through wire sized for 1 A seems ... unlikely?

-Original Message-
From: cctalk  On Behalf Of Mike Katz via cctalk
Sent: Wednesday, December 8, 2021 5:58 PM
To: General Discussion: On-Topic and Off-Topic Posts ; 
wrco...@wrcooke.net
Subject: Re: PDP-11/70 Boards

More accurately up to it's rated wattage "Power = Voltage * Current" 
after all.

If you have a 100W max variac you can draw 20A @ 5V (approx) but only 1A at 
100V.

On 12/8/2021 4:44 PM, Mike Katz via cctalk wrote:
> "As a general rule, a variable transformer (Variac) can provide full 
> rated current at any output voltage. So a 2.5A unit can provide 2.5 A 
> at 1V, 10V, 120V, etc. With a 20V output, that is 50 VA (Watts, sort 
> of)."
>
> Up to the current rating of the variac.  When you draw more current 
> than the transformer can deliver then the voltage will sag.
>
> On 12/8/2021 4:22 PM, Will Cooke via cctalk wrote:
>>
>>> On 12/08/2021 3:58 PM Rob Jarratt via cctalk 
>>> wrote:
>>> So, to supply the bricks on the bench, would a variac rated at 2.5A 
>>> be OK? I am not sure I know how much current the bricks will draw at 
>>> 20VAC, and at what voltage the 2.5A rating is given. Otherwise, 
>>> would this do the trick?
>>> https://cpc.farnell.com/block/steu250-48/transformer-250va-230-400v-
>>> 2-x/dp/TF01418?st=24v%20transformer
>>>
>>> Thanks
>>>
>>> Rob
>>>
>>>
>>>>> JRJ
>> As a general rule, a variable transformer (Variac) can provide full 
>> rated current at any output voltage.  So a 2.5A unit can provide 2.5 
>> A at 1V, 10V, 120V, etc.  With a 20V output, that is 50 VA (Watts, 
>> sort of).
>>
>> Will
>>
>> "I was born not knowing and have had only a little time to change 
>> that here and there."
>> Richard Feynman
>

Re: PDP-11/70 Boards

[Mike Katz via cctalk]

More accurately up to it's rated wattage "Power = Voltage * Current" 
after all.


If you have a 100W max variac you can draw 20A @ 5V (approx) but only 1A 
at 100V.


On 12/8/2021 4:44 PM, Mike Katz via cctalk wrote:
"As a general rule, a variable transformer (Variac) can provide full 
rated current at any output voltage. So a 2.5A unit can provide 2.5 A 
at 1V, 10V, 120V, etc. With a 20V output, that is 50 VA (Watts, sort 
of)."


Up to the current rating of the variac.  When you draw more current 
than the transformer can deliver then the voltage will sag.


On 12/8/2021 4:22 PM, Will Cooke via cctalk wrote:


On 12/08/2021 3:58 PM Rob Jarratt via cctalk  
wrote:
So, to supply the bricks on the bench, would a variac rated at 2.5A 
be OK? I am not sure I know how much current the bricks will draw at 
20VAC, and at what voltage the 2.5A rating is given. Otherwise, 
would this do the trick? 
https://cpc.farnell.com/block/steu250-48/transformer-250va-230-400v-2-x/dp/TF01418?st=24v%20transformer


Thanks

Rob



JRJ
As a general rule, a variable transformer (Variac) can provide full 
rated current at any output voltage.  So a 2.5A unit can provide 2.5 
A at 1V, 10V, 120V, etc.  With a 20V output, that is 50 VA (Watts, 
sort of).


Will

"I was born not knowing and have had only a little time to change 
that here and there."

Richard Feynman

Re: PDP-11/70 Boards

[Mike Katz via cctalk]

"As a general rule, a variable transformer (Variac) can provide full 
rated current at any output voltage. So a 2.5A unit can provide 2.5 A at 
1V, 10V, 120V, etc. With a 20V output, that is 50 VA (Watts, sort of)."


Up to the current rating of the variac.  When you draw more current than 
the transformer can deliver then the voltage will sag.


On 12/8/2021 4:22 PM, Will Cooke via cctalk wrote:



On 12/08/2021 3:58 PM Rob Jarratt via cctalk  wrote:
So, to supply the bricks on the bench, would a variac rated at 2.5A be OK? I am 
not sure I know how much current the bricks will draw at 20VAC, and at what 
voltage the 2.5A rating is given. Otherwise, would this do the trick? 
https://cpc.farnell.com/block/steu250-48/transformer-250va-230-400v-2-x/dp/TF01418?st=24v%20transformer

Thanks

Rob



JRJ

As a general rule, a variable transformer (Variac) can provide full rated 
current at any output voltage.  So a 2.5A unit can provide 2.5 A at 1V, 10V, 
120V, etc.  With a 20V output, that is 50 VA (Watts, sort of).

Will

"I was born not knowing and have had only a little time to change that here and 
there."
Richard Feynman

RE: PDP-11/70 Boards

[Will Cooke via cctalk]

> On 12/08/2021 3:58 PM Rob Jarratt via cctalk  wrote:

> So, to supply the bricks on the bench, would a variac rated at 2.5A be OK? I 
> am not sure I know how much current the bricks will draw at 20VAC, and at 
> what voltage the 2.5A rating is given. Otherwise, would this do the trick? 
> https://cpc.farnell.com/block/steu250-48/transformer-250va-230-400v-2-x/dp/TF01418?st=24v%20transformer
> 
> Thanks
> 
> Rob
> 
> 
> > >
> > > JRJ

As a general rule, a variable transformer (Variac) can provide full rated 
current at any output voltage.  So a 2.5A unit can provide 2.5 A at 1V, 10V, 
120V, etc.  With a 20V output, that is 50 VA (Watts, sort of).

Will

"I was born not knowing and have had only a little time to change that here and 
there."
Richard Feynman

RE: PDP-11/70 Boards

[Rob Jarratt via cctalk]

> > -Original Message-
> > From: cctalk  On Behalf Of Jay Jaeger
> > via cctalk
> > Sent: 05 December 2021 14:51
> > To: cctalk@classiccmp.org
> > Subject: Re: PDP-11/70 Boards
> >
> > On 12/5/2021 3:37 AM, Rob Jarratt via cctalk wrote:
> >
> > > Thanks for the tips. The transformer that drives the bricks is a real 
> > > beast.
> > Did you find an alternative more convenient way to power them on the
> > bench?
> > >
> >
> >  From the schematics, some of them seem to want 20-30 VAC (some, like
> > at least one of the -15v regulators, take DC inputs from other
> > regulators)
> >
> > For lower current initial testing I have some 24v 2A transformers
> > lying around.  For higher current, I might use something like this guy:
> >
> > https://www.digikey.com/en/products/detail/triad-magnetics/F-
> > 401U/5032226
> 

> I have a variac rated at 2.5A. I am not quite sure whether that would be
> sufficient to test the bricks individually. Otherwise, I guess one of these
> would do the trick https://cpc.farnell.com/block/steu250-48/transformer-
> 250va-230-400v-2-x/dp/TF01418?st=24v%20transformer ?

So, to supply the bricks on the bench, would a variac rated at 2.5A be OK? I am 
not sure I know how much current the bricks will draw at 20VAC, and at what 
voltage the 2.5A rating is given. Otherwise, would this do the trick? 
https://cpc.farnell.com/block/steu250-48/transformer-250va-230-400v-2-x/dp/TF01418?st=24v%20transformer

Thanks

Rob


> 
> >
> > JRJ

Re: PDP-11/70 Boards

[Fritz Mueller via cctalk]

> On Dec 5, 2021, at 1:37 AM, Rob Jarratt  wrote:
> I don't see the Kunkin unit for sale except for a couple of items on ebay 
> from China. I am really reluctant to buy anything at all from China. I 
> couldn't find a manufacturer site for them, and I was wondering if there are 
> alternatives since they don't seem to be particularly available.

Yes, just about any programmable DC load in this class will suffice.  It’s just 
convenient to be able to punch in current or power limits, dial them up and 
down, and have everything including fans, thermal management, etc. in one 
compact package on the bench.

At the time I was looking, the Kunkin, while yes, from China, had a lot 
hands-on reviews on YouTube.  So I just went ahead with that.  Worked out okay 
for me, but one kind of annoying thing is the banana jacks on the five-way 
binding posts don’t seem quite standard (!) — I will probably change out the 
posts on mine.

Re: PDP-11/70 Boards

[Fritz Mueller via cctalk]

> On 12/5/2021 3:37 AM, Rob Jarratt via cctalk wrote:
> Thanks for the tips. The transformer that drives the bricks is a real beast.  
> Did you find an alternative more convenient way to power them on the bench?

No, I just used the big transformer, since I needed to bench and disassemble 
the H742s themselves for cleaning, inspection, and repairs anyway.

RE: PDP-11/70 Boards

[Rob Jarratt via cctalk]

> -Original Message-
> From: cctalk  On Behalf Of Jay Jaeger via
> cctalk
> Sent: 05 December 2021 14:51
> To: cctalk@classiccmp.org
> Subject: Re: PDP-11/70 Boards
> 
> On 12/5/2021 3:37 AM, Rob Jarratt via cctalk wrote:
> 
> > Thanks for the tips. The transformer that drives the bricks is a real beast.
> Did you find an alternative more convenient way to power them on the
> bench?
> >
> 
>  From the schematics, some of them seem to want 20-30 VAC (some, like at
> least one of the -15v regulators, take DC inputs from other regulators)
> 
> For lower current initial testing I have some 24v 2A transformers lying
> around.  For higher current, I might use something like this guy:
> 
> https://www.digikey.com/en/products/detail/triad-magnetics/F-
> 401U/5032226

I have a variac rated at 2.5A. I am not quite sure whether that would be 
sufficient to test the bricks individually. Otherwise, I guess one of these 
would do the trick 
https://cpc.farnell.com/block/steu250-48/transformer-250va-230-400v-2-x/dp/TF01418?st=24v%20transformer
 ?

> 
> JRJ

Re: PDP-11/70 Boards

[Jay Jaeger via cctalk]

On 12/5/2021 3:37 AM, Rob Jarratt via cctalk wrote:


Thanks for the tips. The transformer that drives the bricks is a real beast. 
Did you find an alternative more convenient way to power them on the bench?



From the schematics, some of them seem to want 20-30 VAC (some, like at 
least one of the -15v regulators, take DC inputs from other regulators)


For lower current initial testing I have some 24v 2A transformers lying 
around.  For higher current, I might use something like this guy:


https://www.digikey.com/en/products/detail/triad-magnetics/F-401U/5032226

JRJ

Re: PDP-11/70 Boards

[Jay Jaeger via cctalk]

On 12/4/2021 5:57 PM, Rob Jarratt wrote:





What kind of load tester are you looking to buy? I have an 11/45 which I need 
to test the power supplies on too.



Oh just one off of amazon, I expect.  One could either get a nice one in 
a cabinet at all for around $280 - $350, depending upon capacity, or an 
less expensive unit for $100 or so.


This one seems intriguing: the price is modest, said to handle up to 
30V, 20A, 200W (could test 5v up to 20A, 15V up to 13A and at 30V, 
derate down to 6A.


https://www.amazon.com/T-king-Battery-Capacity-Tester-Electronic/dp/B07SFD8R4Y


Here is a slightly more capable unit in a nicer case for $300

https://www.amazon.com/Electronic-Tester-Programmable-Channel-Battery/dp/B091FFSHD5

RE: PDP-11/70 Boards

[Rob Jarratt via cctalk]

Thanks for the tips. The transformer that drives the bricks is a real beast. 
Did you find an alternative more convenient way to power them on the bench?

I don't see the Kunkin unit for sale except for a couple of items on ebay from 
China. I am really reluctant to buy anything at all from China. I couldn't find 
a manufacturer site for them, and I was wondering if there are alternatives 
since they don't seem to be particularly available. I did find this which is a 
bit more expensive (I know Rigol is Chinese, but it seems to be decent quality 
kit) 
https://www.rigol-uk.co.uk/product/rigol-dl3021-programmable-dc-electronic-load/

Thanks

Rob

> -Original Message-
> From: cctalk  On Behalf Of Fritz Mueller via
> cctalk
> Sent: 05 December 2021 01:03
> To: General Discussion: On-Topic and Off-Topic Posts
> 
> Subject: Re: PDP-11/70 Boards
> 
> 
> 
> > On Dec 4, 2021, at 3:57 PM, Rob Jarratt via cctalk 
> wrote:
> > What kind of load tester are you looking to buy? I have an 11/45 which I
> need to test the power supplies on too.
> 
> I picked up a Kunkin KP184 this last year, and it does nicely for testing 
> those
> brick regulators and the power control boards in isolation (a bit more
> convenient than the old light bulb or power resistor approach.)
> 
> Some of the large electrolytics in those bricks will likely have dried out.  I
> disassemble and “reform" these with a bench supply and current limiting
> resistor on any of these bricks I have not yet personally serviced (Yes, I 
> know
> the reforming thing is controversial for some.  I think its safe to say it at 
> least
> doesn’t hurt anything :-)
> 
> Check the big bridge rectifiers carefully; I’ve seen a few of those cracked or
> toasted.
> 
> It’s also been my experience that beyond the bricks that are dead or fail at
> the start, some smaller fraction will also let go after the first few hours of
> continuous operation.  The don’t tend to fail with fireworks — you’ll
> generally get a slowly increasing whiff of magic smoke so generally plenty of
> time to shut things down.
> 
> The operation indicator bulbs on these seem almost always dead.  You can
> sub CM7381 for the +5V regulators, and OL-6003BP for the -15V.
> 
> Last, if you have H742 supplies on your 11/45, be sure to check the small
> muffin fan above the power control board. It is quite common for parts of
> the internal wiring harness to rub up against these and stall them out,
> eventually leading to a fried controller board.
> 
> Good luck!  Good winter time project :-)
> 
> —FritzM.

Re: PDP-11/70 Boards

[Jon Elson via cctalk]

On 12/4/21 7:02 PM, Fritz Mueller via cctalk wrote:



On Dec 4, 2021, at 3:57 PM, Rob Jarratt via cctalk  
wrote:
What kind of load tester are you looking to buy? I have an 11/45 which I need 
to test the power supplies on too.


My experience with an 11/45 (serial # 343) was that the 
regulators were pretty indestructable, but the AMP 
Mate-n-Lok connectors burned up on a regular basis.


Jon

Re: PDP-11/70 Boards

[Fritz Mueller via cctalk]

> On Dec 4, 2021, at 3:57 PM, Rob Jarratt via cctalk  
> wrote:
> What kind of load tester are you looking to buy? I have an 11/45 which I need 
> to test the power supplies on too.

I picked up a Kunkin KP184 this last year, and it does nicely for testing those 
brick regulators and the power control boards in isolation (a bit more 
convenient than the old light bulb or power resistor approach.)

Some of the large electrolytics in those bricks will likely have dried out.  I 
disassemble and “reform" these with a bench supply and current limiting 
resistor on any of these bricks I have not yet personally serviced (Yes, I know 
the reforming thing is controversial for some.  I think its safe to say it at 
least doesn’t hurt anything :-)

Check the big bridge rectifiers carefully; I’ve seen a few of those cracked or 
toasted.

It’s also been my experience that beyond the bricks that are dead or fail at 
the start, some smaller fraction will also let go after the first few hours of 
continuous operation.  The don’t tend to fail with fireworks — you’ll generally 
get a slowly increasing whiff of magic smoke so generally plenty of time to 
shut things down.

The operation indicator bulbs on these seem almost always dead.  You can sub 
CM7381 for the +5V regulators, and OL-6003BP for the -15V.

Last, if you have H742 supplies on your 11/45, be sure to check the small 
muffin fan above the power control board. It is quite common for parts of the 
internal wiring harness to rub up against these and stall them out, eventually 
leading to a fried controller board.

Good luck!  Good winter time project :-)

—FritzM.

RE: PDP-11/70 Boards

[Rob Jarratt via cctalk]

> -Original Message-
> From: cctalk  On Behalf Of Jay Jaeger via
> cctalk
> Sent: 04 December 2021 23:21
> To: cctalk@classiccmp.org
> Subject: Re: PDP-11/70 Boards
> 
> On 12/1/2021 11:55 AM, Noel Chiappa via cctalk wrote:
> >  > From the blog of someone who got a KB11-A working
> >
> > It's Fritz Mueller's blog; at about the top of this page:
> >
> >https://fritzm.github.io/category/pdp-116.html
> >
> > he's just turned the machine on for the first time, and you can follow
> > as he chases, finds and fixes CPU problems. The KB11-C/D of the -11/70
> > is _very_ similar to the KB11-A he was dealing with (they are
> > _basically_ the same CPU, with a cache, and other stuff added on the
> > other side from the CPU, on the KB11-C/D), so there are probably some
> > good lessons to be learned.
> >
> 
> Very useful to see as I ponder trying to get my 11/45 (with a KB11-D in
> it) going again.  I think next time I work on this beastie I will roll it out 
> from my
> main room where the lighting and access are just OK into my larger room
> where my PC is kept temporarily, for easier access.
> Going to want to buy a load tester and thoroughly check out the power
> supplies first - which are unfortunately really heavy (and may not be
> mounted quite properly, either), as it has been several years since I turned
> the thing on.

What kind of load tester are you looking to buy? I have an 11/45 which I need 
to test the power supplies on too.

> 
> JRJ

Re: PDP-11/70 Boards

[Jay Jaeger via cctalk]

On 12/1/2021 11:55 AM, Noel Chiappa via cctalk wrote:

 > From the blog of someone who got a KB11-A working

It's Fritz Mueller's blog; at about the top of this page:

   https://fritzm.github.io/category/pdp-116.html

he's just turned the machine on for the first time, and you can
follow as he chases, finds and fixes CPU problems. The KB11-C/D
of the -11/70 is _very_ similar to the KB11-A he was dealing with
(they are _basically_ the same CPU, with a cache, and other stuff
added on the other side from the CPU, on the KB11-C/D), so there
are probably some good lessons to be learned.



Very useful to see as I ponder trying to get my 11/45 (with a KB11-D in 
it) going again.  I think next time I work on this beastie I will roll 
it out from my main room where the lighting and access are just OK into 
my larger room where my PC is kept temporarily, for easier access. 
Going to want to buy a load tester and thoroughly check out the power 
supplies first - which are unfortunately really heavy (and may not be 
mounted quite properly, either), as it has been several years since I 
turned the thing on.


JRJ

Re: PDP-11/70 Boards

[Noel Chiappa via cctalk]

> From: Guy Sotomayor

> I don't unfortunately have any light masks

Dave Bridgham and I were manoeuvreing to be able to produce clones of the one
you loaned me (he has access to a computer-controlled milling machine at his
maker-space or whatever the name is for them now, and we bought a good-sized
sheet of the required plastic to be able to crank them out) when I came down
with COVID early in the pendemic, and in the aftermath (I came down with
long-haul post-COVID Chronic Fatigue Syndrome) itgot put on hold. The loaner,
and a micrometer to measure it, are still siting on the table in my family
room, next to my desktop.

If anybody needs some, I can probably try finishing the drawing, and get it
to Dave, so we can resume that project.


Noel

Re: PDP-11/70 Boards

[Noel Chiappa via cctalk]

> From the blog of someone who got a KB11-A working

It's Fritz Mueller's blog; at about the top of this page:

  https://fritzm.github.io/category/pdp-116.html

he's just turned the machine on for the first time, and you can
follow as he chases, finds and fixes CPU problems. The KB11-C/D
of the -11/70 is _very_ similar to the KB11-A he was dealing with
(they are _basically_ the same CPU, with a cache, and other stuff
added on the other side from the CPU, on the KB11-C/D), so there
are probably some good lessons to be learned.


> dunno if Guy Steele

Ooops; sorry, Guy - the brain is starting to drop bits.


> if the particular machine the system is being built for has an FP11).
> Perhaps the later BSD versions look for the FP11 on startup, and adjust
> their behaviour appropriately, but I'm not familiar with them.

The way user code deals with the existence/non-existence of the FP11 is
pretty simple.

In C (other languages probably do something similar, but I only know about
C),one gives the '-f' flag to 'cc', and when 'cc' invokes the linker, on
machines which don't have floating point support, it uses fcrt0:

  https://minnie.tuhs.org/cgi-bin/utree.pl?file=V6/usr/source/s4/fcrt0.s

as the machine language startup (the thing that calls main()) instead of
crt0. The difference is that fcrt0 sets the UNIX 'illegal instruction'
signal, in that process, to go to a handler which emulates the FP11
instructions.

In V6, as distributed, the binary of all applications which use floating
point are linked this way, so they will all run OK 'as is' on a machine with
no floating point (including those which don't suppport any kind of FP11,
such as the -11/40). When run on a machine with an FP11, there are no illegal
instruction traps, and that emulator code is just never used.

I'm not sure what the deal with BSD is, for machines without an FP11; fcrt0.s
is still included in BSD2.9, so maybe it's still using this approach. I have
this vague recollection that at some point, floating point instruction
emulation was added to the kernel, removing all the signal overhead, but that
might be a bogus recollection.

Noel

Re: PDP-11/70 Boards

[Scott LaBombard via cctalk]

   On Tuesday, November 30, 2021, 04:24:37 PM EST, Jay Jaeger via cctalk 
 wrote:  > 
>
>Did you use that directly with ExpressPCB and order from ExpressPCB or 
>did you convert to more standard gerbers?

I have a gerber archive for the km11x.pcb file. If anyone can host it where it 
might be more broadly accessible, I'd be happy to send it along to them.


Scott
  

Re: PDP-11/70 Boards

[Todd Goodman via cctalk]

On 11/30/2021 4:42 PM, Fritz Mueller via cctalk wrote:

I built mine from a layout on Tom Uban’s site: 
http://www.ubanproductions.com/museum.html
Did you use that directly with ExpressPCB and order from ExpressPCB or did you 
convert to more standard gerbers?

I just went with ExpressPCB for minimal hassle, but you could probably get it 
cheaper from other board houses these days.  For my KB11-A + FP11-B, which run 
asynchronously, it was handy to build up two of these.  Also useful for the 
RK11-C.

   —FritzM.


I have Joerg Hoppe's KM11 bare boards available.

He also has gerbers available at 
http://retrocmp.com/tools/dec-km11-maintenance-panel


Todd

Re: PDP-11/70 Boards

[Jay Jaeger via cctalk]

On 11/30/2021 6:31 PM, Paul Koning wrote:




On Nov 30, 2021, at 7:17 PM, Jay Jaeger via cctalk  
wrote:

...
The issue is (I think) that the ExpressPCB software can only be used to create 
files to order boards from them - or can it now export ordinary gerbers?  
(Otherwise, to go with another fab. I presumably would re-enter the schematic, 
and re-route it - granted not all *that* hard, but still a day's work.


You're right, they say so in the FAQ.  And it is the reason I don't use them.

At one point I used PCB Pool (Beta layout) because they could take Eagle files 
directly.  But sending boards across the ocean isn't so economical.  And Eagle 
became less and less attractive over time.

My current answer is KiCAD which is open source and somewhat more powerful than 
Eagle (without the hassles).  Both do Gerbers, but there are also fabs that 
take the CAD files directly.  OSHPark is the one I've used for my most recent 3 
projects, they do nice work.  The color is odd, but what the heck, it still 
works.

paul



I have used KiCAD for several projects.  I like it, though the 
developers don't always seem to allow for the pain the cause when they 
make version changes that requires a lot of footprint re-hunting.  ;)


JRJ

Re: PDP-11/70 Boards

[Fritz Mueller via cctalk]

> On Nov 30, 2021, at 7:17 PM, Jay Jaeger via cctalk  
> wrote:
> The issue is (I think) that the ExpressPCB software can only be used to 
> create files to order boards from them


> On Nov 30, 2021, at 4:31 PM, Paul Koning via cctalk  
> wrote:
> You're right, they say so in the FAQ.  And it is the reason I don't use them.

Oh, I hadn’t realized they have the whole lock-in thing going; that’s kind of 
obnoxious!

> My current answer is KiCAD which is open source and somewhat more powerful 
> than Eagle (without the hassles).

KiCAD is pretty nice these days.  A friend also recently introduced me to jlpcb 
and pcbway, and the prices and turnaround times from both of these board 
houses, even for very small runs, are amazing!  jlpcb will also do assembly of 
many stocked surface mount parts at very reasonable prices.

  —FritzM.

Re: PDP-11/70 Boards

[Paul Koning via cctalk]

> On Nov 30, 2021, at 7:17 PM, Jay Jaeger via cctalk  
> wrote:
> 
> ...
> The issue is (I think) that the ExpressPCB software can only be used to 
> create files to order boards from them - or can it now export ordinary 
> gerbers?  (Otherwise, to go with another fab. I presumably would re-enter the 
> schematic, and re-route it - granted not all *that* hard, but still a day's 
> work.

You're right, they say so in the FAQ.  And it is the reason I don't use them.

At one point I used PCB Pool (Beta layout) because they could take Eagle files 
directly.  But sending boards across the ocean isn't so economical.  And Eagle 
became less and less attractive over time.

My current answer is KiCAD which is open source and somewhat more powerful than 
Eagle (without the hassles).  Both do Gerbers, but there are also fabs that 
take the CAD files directly.  OSHPark is the one I've used for my most recent 3 
projects, they do nice work.  The color is odd, but what the heck, it still 
works.

paul

Re: PDP-11/70 Boards

[Jay Jaeger via cctalk]

On 11/30/2021 3:52 PM, Henk Gooijen via cctalk wrote:

Van: Fritz Mueller via cctalk<mailto:cctalk@classiccmp.org>
Verzonden: dinsdag 30 november 2021 22:43
Aan: General Discussion: On-Topic and Off-Topic 
Posts<mailto:cctalk@classiccmp.org>
Onderwerp: Re: PDP-11/70 Boards



I built mine from a layout on Tom Uban’s site: 
http://www.ubanproductions.com/museum.html



Did you use that directly with ExpressPCB and order from ExpressPCB or did you 
convert to more standard gerbers?


I just went with ExpressPCB for minimal hassle, but you could probably get it 
cheaper from other board houses these days.  For my KB11-A + FP11-B, which run 
asynchronously, it was handy to build up two of these.  Also useful for the 
RK11-C.

   —FritzM.

And useful for PDP-11/05, PDP-11/10, PDP-11/20, PDP-11/35, PDP-11/40 … more?
Henk, PA8PDP



The issue is (I think) that the ExpressPCB software can only be used to 
create files to order boards from them - or can it now export ordinary 
gerbers?  (Otherwise, to go with another fab. I presumably would 
re-enter the schematic, and re-route it - granted not all *that* hard, 
but still a day's work.


JRJ

RE: PDP-11/70 Boards

[Henk Gooijen via cctalk]

Van: Henk Gooijen via cctalk<mailto:cctalk@classiccmp.org>
Verzonden: dinsdag 30 november 2021 22:52
Aan: General Discussion: On-Topic and Off-Topic 
Posts<mailto:cctalk@classiccmp.org>
Onderwerp: RE: PDP-11/70 Boards

Van: Fritz Mueller via cctalk<mailto:cctalk@classiccmp.org>
Verzonden: dinsdag 30 november 2021 22:43
Aan: General Discussion: On-Topic and Off-Topic 
Posts<mailto:cctalk@classiccmp.org>
Onderwerp: Re: PDP-11/70 Boards


> I built mine from a layout on Tom Uban’s site: 
> http://www.ubanproductions.com/museum.html

> Did you use that directly with ExpressPCB and order from ExpressPCB or did 
> you convert to more standard gerbers?

I just went with ExpressPCB for minimal hassle, but you could probably get it 
cheaper from other board houses these days.  For my KB11-A + FP11-B, which run 
asynchronously, it was handy to build up two of these.  Also useful for the 
RK11-C.

  —FritzM.

And useful for PDP-11/05, PDP-11/10, PDP-11/20, PDP-11/35, PDP-11/40 … more?
Henk, PA8PDP
I also seem to remember the RX01 (and RX02?)

RE: PDP-11/70 Boards

[Henk Gooijen via cctalk]

Van: Fritz Mueller via cctalk<mailto:cctalk@classiccmp.org>
Verzonden: dinsdag 30 november 2021 22:43
Aan: General Discussion: On-Topic and Off-Topic 
Posts<mailto:cctalk@classiccmp.org>
Onderwerp: Re: PDP-11/70 Boards


> I built mine from a layout on Tom Uban’s site: 
> http://www.ubanproductions.com/museum.html

> Did you use that directly with ExpressPCB and order from ExpressPCB or did 
> you convert to more standard gerbers?

I just went with ExpressPCB for minimal hassle, but you could probably get it 
cheaper from other board houses these days.  For my KB11-A + FP11-B, which run 
asynchronously, it was handy to build up two of these.  Also useful for the 
RK11-C.

  —FritzM.

And useful for PDP-11/05, PDP-11/10, PDP-11/20, PDP-11/35, PDP-11/40 … more?
Henk, PA8PDP

Re: PDP-11/70 Boards

[Fritz Mueller via cctalk]

> I built mine from a layout on Tom Uban’s site: 
> http://www.ubanproductions.com/museum.html 

> Did you use that directly with ExpressPCB and order from ExpressPCB or did 
> you convert to more standard gerbers?

I just went with ExpressPCB for minimal hassle, but you could probably get it 
cheaper from other board houses these days.  For my KB11-A + FP11-B, which run 
asynchronously, it was handy to build up two of these.  Also useful for the 
RK11-C.

  —FritzM.

Re: PDP-11/70 Boards

[Jay Jaeger via cctalk]

On 11/30/2021 2:04 PM, Fritz Mueller via cctalk wrote:


On 11/30/21 10:06 AM, Noel Chiappa via cctalk wrote:
 From the blog of someone who got a KB11-A working, you'll really need KM11
cards...



On Nov 30, 2021, at 10:59 AM, Guy Sotomayor via cctalk  
wrote:
I do still have KM11 boards and some overlays (I'd have to check to see if I 
have the appropriate overlays for the 11/70).  I don't unfortunately have any 
light masks or full kits.


I built mine from a layout on Tom Uban’s site: 
http://www.ubanproductions.com/museum.html 
.  I have found the single long 
board form factor convenient, but they don’t have nice light dividers and overlays 
like Guy’s.

Agreed that at least one of these, as well as a hex extender card, are 
absolutely essential if you need to debug CPU/MMU/FPU cards (which, given their 
age, is nearly guaranteed unless you are getting them pre-checked/repaired from 
another restorer.)

  —FritzM.




Did you use that directly with ExpressPCB and order from ExpressPCB or 
did you convert to more standard gerbers?  (This thread has me 
motiviated to maybe get my 11/45 running again next year, and verify or 
fix my FP11-C)


[Note,  I have also been corresponding with the OP on purchase of my 4 
"spare" boards for an FP11-C]


JRJ

Re: PDP-11/70 Boards

[Fritz Mueller via cctalk]

> On 11/30/21 10:06 AM, Noel Chiappa via cctalk wrote:
> From the blog of someone who got a KB11-A working, you'll really need KM11
> cards...

> On Nov 30, 2021, at 10:59 AM, Guy Sotomayor via cctalk 
>  wrote:
> I do still have KM11 boards and some overlays (I'd have to check to see if I 
> have the appropriate overlays for the 11/70).  I don't unfortunately have any 
> light masks or full kits.

I built mine from a layout on Tom Uban’s site: 
http://www.ubanproductions.com/museum.html 
.  I have found the single long 
board form factor convenient, but they don’t have nice light dividers and 
overlays like Guy’s.

Agreed that at least one of these, as well as a hex extender card, are 
absolutely essential if you need to debug CPU/MMU/FPU cards (which, given their 
age, is nearly guaranteed unless you are getting them pre-checked/repaired from 
another restorer.)

 —FritzM.

Re: PDP-11/70 Boards

[Guy Sotomayor via cctalk]

On 11/30/21 10:06 AM, Noel Chiappa via cctalk wrote:


 From the blog of someone who got a KB11-A working, you'll really need KM11
cards; dunno if Guy Steele still has those clones he was selling.


I think you meant me.  Guy Steele is from Common LISP fame.  ;-)

I do still have KM11 boards and some overlays (I'd have to check to see 
if I have the appropriate overlays for the 11/70).  I don't 
unfortunately have any light masks or full kits.


--
TTFN - Guy

Re: PDP-11/70 Boards

[Ed C. via cctalk]

Very helpful! Thank you

On Tue, Nov 30, 2021, 19:06 Noel Chiappa  wrote:

> > From: Ed Cross
>
> > I'm currently restoring a PDP-11/70 system and need the following
> > boards to complete the CPU: FP11-C
>
> From your mention of the FP11-C, I gather your -11/70 has a KB11-C (later)
> CPU, not the KB11-B CPU of the earlier PDP-11/70's (prior to 1976 - the
> difference between the two was whether they took the optional FP11-B or
> FP11-C
> FPP).
>
> Not that it makes a big difference in your case; the 4 cache cards are the
> same in both.
>
> There used to be a seller on eBait (on the mid-East Coast - Baltimore,
> IIRC)
> who was selling -11/70 CPU cards (I bought a whole spare set from him) but
> alas he seems to have gone away (or sold them all; a quick search, both on
> eBait, and in my email, didn't turm him up; I can institute a deeper search
> if need be).
>
> From the blog of someone who got a KB11-A working, you'll really need KM11
> cards; dunno if Guy Steele still has those clones he was selling.
>
>
> There are definitely some versions of Unix which will run fine on -11/70's
> without the FP11 (e.g. V6). The system binary is different for the
> with/without versions, though: in the assembler code which saves the state
> of
> one process before switching to another, there is code like:
>
> stfps   (r1)+
>
> which will probably get an illegal instruction trap in kernel mode on a
> machine with no FP11, and is therefore conditionally assembled (depending
> on
> if the particular machine the system is being built for has an FP11).
> Perhaps
> the later BSD versions look for the FP11 on startup, and adjust their
> behaviour appropriately, but I'm not familiar with them.
>
> V6 as distributed contains system binary for an -11/40, which will run on
> _any_ -11 UNIX will run on, and can be used to build appropriate system
> binary.
>
>
> (Diversion: I've never found out whether the KB11-B and KB11-C of the
> -11/70
> used/could use the same backplane or not. By examining the prints for the
> boards of the FP11-B and FP11-C, and seeing on which pins they exchanged
> signals, and what signals they exchanged with the rest of the CPU, and on
> which pins, it should be possible to work it out. Ditto for the M8133 ROM
> and
> ROM Control of the KB11-B, replaced with the M8123 in the KB11-C.)
>
> (Interesting factoid: the M8123 is the only card shared between any variant
> of the -11/45 and -11/70: both the KB11-C and KB11-D use it. Of course, I
> think we're still missing a wirelist for the -11/70 backplane, of any
> variant; and the ECO history. There appears to have been at least one
> poorly
> documented upgrade; see here:
>
>   http://gunkies.org/wiki/MK11_memory_system#CSR_Access
>
> for more.)
>
> Noel
>

Re: PDP-11/70 Boards

[Noel Chiappa via cctalk]

> From: Ed Cross

> I'm currently restoring a PDP-11/70 system and need the following
> boards to complete the CPU: FP11-C

>From your mention of the FP11-C, I gather your -11/70 has a KB11-C (later)
CPU, not the KB11-B CPU of the earlier PDP-11/70's (prior to 1976 - the
difference between the two was whether they took the optional FP11-B or FP11-C
FPP).

Not that it makes a big difference in your case; the 4 cache cards are the
same in both.

There used to be a seller on eBait (on the mid-East Coast - Baltimore, IIRC)
who was selling -11/70 CPU cards (I bought a whole spare set from him) but
alas he seems to have gone away (or sold them all; a quick search, both on
eBait, and in my email, didn't turm him up; I can institute a deeper search
if need be).

>From the blog of someone who got a KB11-A working, you'll really need KM11
cards; dunno if Guy Steele still has those clones he was selling.


There are definitely some versions of Unix which will run fine on -11/70's
without the FP11 (e.g. V6). The system binary is different for the
with/without versions, though: in the assembler code which saves the state of
one process before switching to another, there is code like:

stfps   (r1)+

which will probably get an illegal instruction trap in kernel mode on a
machine with no FP11, and is therefore conditionally assembled (depending on
if the particular machine the system is being built for has an FP11). Perhaps
the later BSD versions look for the FP11 on startup, and adjust their
behaviour appropriately, but I'm not familiar with them.

V6 as distributed contains system binary for an -11/40, which will run on
_any_ -11 UNIX will run on, and can be used to build appropriate system
binary.


(Diversion: I've never found out whether the KB11-B and KB11-C of the -11/70
used/could use the same backplane or not. By examining the prints for the
boards of the FP11-B and FP11-C, and seeing on which pins they exchanged
signals, and what signals they exchanged with the rest of the CPU, and on
which pins, it should be possible to work it out. Ditto for the M8133 ROM and
ROM Control of the KB11-B, replaced with the M8123 in the KB11-C.)

(Interesting factoid: the M8123 is the only card shared between any variant
of the -11/45 and -11/70: both the KB11-C and KB11-D use it. Of course, I
think we're still missing a wirelist for the -11/70 backplane, of any
variant; and the ECO history. There appears to have been at least one poorly
documented upgrade; see here:

  http://gunkies.org/wiki/MK11_memory_system#CSR_Access

for more.)

Noel

Re: PDP-11/70 Boards

[Paul Koning via cctalk]

> On Nov 29, 2021, at 4:12 PM, Josh Dersch via cctalk  
> wrote:
> 
> On Mon, Nov 29, 2021 at 1:06 PM Ethan Dicks via cctalk <
> cctalk@classiccmp.org> wrote:
> 
>> On Mon, Nov 29, 2021 at 3:19 PM Henk Gooijen via cctalk
>>  wrote:
>>> I think the FP11 boards are not essential for the 11/70
>>> They only add hardware FP support.
>> 
>> Not essential for many uses, but I'm pretty sure UNIX is unhappy
>> without them.  If you are going to run RSTS/E or RT-11, should be just
>> fine either way.
>> 
> 
> Depends on the UNIX.  Ultrix works fine, and the latest patchlevel of
> 2.11BSD has floating point simulation that works fine.
> 
> (I'm running my 11/70 sans floating point hardware at the moment, I'd still
> like to find a boardset one of these days, though.  Floating point
> emulation is slow!)

Another option would be a compiler that generates no-FP code.  That's faster 
than emulation.  gcc can do that; does 2.x BSD cc have such an option?

paul

Re: PDP-11/70 Boards

[Josh Dersch via cctalk]

On Mon, Nov 29, 2021 at 1:06 PM Ethan Dicks via cctalk <
cctalk@classiccmp.org> wrote:

> On Mon, Nov 29, 2021 at 3:19 PM Henk Gooijen via cctalk
>  wrote:
> > I think the FP11 boards are not essential for the 11/70
> > They only add hardware FP support.
>
> Not essential for many uses, but I'm pretty sure UNIX is unhappy
> without them.  If you are going to run RSTS/E or RT-11, should be just
> fine either way.
>

Depends on the UNIX.  Ultrix works fine, and the latest patchlevel of
2.11BSD has floating point simulation that works fine.

(I'm running my 11/70 sans floating point hardware at the moment, I'd still
like to find a boardset one of these days, though.  Floating point
emulation is slow!)


>
> > However, I think that the cache boards are essential.
> > Not sure the 11/70 will work without them.
>
> Agreed.  I think those _are_ mandatory.
>

Yes, the cache is an integral part of the memory system on the 11/70.

- Josh



> Cheers,
>
> -ethan
>

Re: PDP-11/70 Boards

[Ethan Dicks via cctalk]

On Mon, Nov 29, 2021 at 3:19 PM Henk Gooijen via cctalk
 wrote:
> I think the FP11 boards are not essential for the 11/70
> They only add hardware FP support.

Not essential for many uses, but I'm pretty sure UNIX is unhappy
without them.  If you are going to run RSTS/E or RT-11, should be just
fine either way.

> However, I think that the cache boards are essential.
> Not sure the 11/70 will work without them.

Agreed.  I think those _are_ mandatory.

Cheers,

-ethan

RE: PDP-11/70 Boards

[Henk Gooijen via cctalk]

Van: Jay Jaeger via cctalk<mailto:cctalk@classiccmp.org>
Verzonden: maandag 29 november 2021 21:05
Aan: cctalk@classiccmp.org<mailto:cctalk@classiccmp.org>
Onderwerp: Re: PDP-11/70 Boards

On 11/29/2021 7:32 AM, Ed C. via cctalk wrote:
> Dear list, I'm currently restoring a PDP-11/70 system and need the
> following boards to complete the CPU:
>
> FP11-C slots:
> M8127
> M8128
> M8129
>
> Cache slots:
> M8142
> M8143
> M8144
> M8145
>
> Any help finding these is appreciated. Thanks.

So, it turns out that I *do* have an FP11-C.  My PDP-11/45 with the
KB11-D processor in it has an FP11-C.  So, at the least, I would need to
try and figure out if the boards in it right now are the ones that came
with it [This is what my notes from 1989/1990 say], or are my spares,
and, at the least one of the two M8126 boards is marked "Bad".

JRJ


I think the FP11 boards are not essential for the 11/70
They only add hardware FP support.
However, I think that the cache boards are essential.
Not sure the 11/70 will work without them.

Henk, PA8PDP

Re: PDP-11/70 Boards

[Jay Jaeger via cctalk]

On 11/29/2021 7:32 AM, Ed C. via cctalk wrote:

Dear list, I'm currently restoring a PDP-11/70 system and need the
following boards to complete the CPU:

FP11-C slots:
M8127
M8128
M8129

Cache slots:
M8142
M8143
M8144
M8145

Any help finding these is appreciated. Thanks.



So, it turns out that I *do* have an FP11-C.  My PDP-11/45 with the 
KB11-D processor in it has an FP11-C.  So, at the least, I would need to 
try and figure out if the boards in it right now are the ones that came 
with it [This is what my notes from 1989/1990 say], or are my spares, 
and, at the least one of the two M8126 boards is marked "Bad".


JRJ

Re: PDP-11/70 Boards

[Jay Jaeger via cctalk]

On 11/29/2021 7:32 AM, Ed C. via cctalk wrote:

Dear list, I'm currently restoring a PDP-11/70 system and need the
following boards to complete the CPU:

FP11-C slots:
M8127
M8128
M8129

Cache slots:
M8142
M8143
M8144
M8145

Any help finding these is appreciated. Thanks.



I presume you'd also need M8126, or is that one there already?

JRJ

Re: PDP-11/70 Boards

[Jay Jaeger via cctalk]

On 11/29/2021 7:32 AM, Ed C. via cctalk wrote:

Dear list, I'm currently restoring a PDP-11/70 system and need the
following boards to complete the CPU:

FP11-C slots:
M8127
M8128
M8129

Cache slots:
M8142
M8143
M8144
M8145

Any help finding these is appreciated. Thanks.



I have M8127, M8128, M8129 (in my basement for > 20 years, condition 
otherwise unknown).  I don't *think* I have an FP11-C in any machine, 
but I will need to check.


Contact me off list for further discussion.

JRJ