Pardon a post about electronic design. In a recent Dave Jones EEVBlog
video nr 1561 ...

<https://www.youtube.com/watch?v=FKC6lnTKH-c>

.... he shows his USB powered variable bench power supply. At about 28:10
the regulator schematic is shown. I am baffled why he uses two series
pass transistors; one for current, one for voltage. I cannot recall ever
seen the functionality split into two power transistors in series
before. Is that laziness or brilliance? Does anyone have ideas about the
design reasoning?

Diode D4 in the voltage regulator does not inspire confidence.

piglet

On Wednesday, August 30, 2023 at 5:11:38 PM UTC-4, piglet wrote:
> Pardon a post about electronic design. In a recent Dave Jones EEVBlog
> video nr 1561 ...
>
> <https://www.youtube.com/watch?v=FKC6lnTKH-c>
>
> ... he shows his USB powered variable bench power supply. At about 28:10
> the regulator schematic is shown. I am baffled why he uses two series
> pass transistors; one for current, one for voltage. I cannot recall ever
> seen the functionality split into two power transistors in series
> before. Is that laziness or brilliance? Does anyone have ideas about the
> design reasoning?
>
> Diode D4 in the voltage regulator does not inspire confidence.

He has a forum. You could just go there and ask him. I'm sure he would love to discuss it with you.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

piglet wrote:
> Pardon a post about electronic design. In a recent Dave Jones EEVBlog
> video nr 1561 ...
>
> <https://www.youtube.com/watch?v=FKC6lnTKH-c>
>
> ... he shows his USB powered variable bench power supply. At about 28:10
> the regulator schematic is shown. I am baffled why he uses two series
> pass transistors; one for current, one for voltage. I cannot recall ever
> seen the functionality split into two power transistors in series
> before. Is that laziness or brilliance? Does anyone have ideas about the
> design reasoning?
>
> Diode D4 in the voltage regulator does not inspire confidence.

A pertinent previous post:

<https://www.eevblog.com/forum/projects/usupply-usb-rev-b-update/>

contains a link to this schematic:

<https://eevblog.com/files/uSupplyUSBrevB.pdf>

Does your SED post pertain to pass transistors Q5 and Q6 shown in the
schematic?

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

On Wednesday, August 30, 2023 at 5:11:38 PM UTC-4, piglet wrote:
> Pardon a post about electronic design. In a recent Dave Jones EEVBlog
> video nr 1561 ...
>
> <https://www.youtube.com/watch?v=FKC6lnTKH-c>
>
> ... he shows his USB powered variable bench power supply. At about 28:10
> the regulator schematic is shown. I am baffled why he uses two series
> pass transistors; one for current, one for voltage. I cannot recall ever
> seen the functionality split into two power transistors in series
> before. Is that laziness or brilliance? Does anyone have ideas about the
> design reasoning?

They use similar in HP benchtops. It's necessary if you want a precision programmable current limit. Until it limits, it's just a saturated FET putting most of the voltage on the voltage regulation FET.

>
> Diode D4 in the voltage regulator does not inspire confidence.

Note on schematic says D4 prevents interference by input diodes ( of error opamp ) on the voltage measurement, meaning at R22+ R23 junction. If I could read the pn of the op amp it would be clear, but it's not readable as is. Maybe it's some quasi-Norton amp. Whatever it is the input is acting on about a diode drop below the voltage at external (+) input.

Schematic symbols of resistors look like inductors. FETs look like RJ-45 connectors.

>
> piglet

On Wed, 30 Aug 2023 22:11:28 +0100, piglet <erichpwagner@hotmail.com>
wrote:

>Pardon a post about electronic design. In a recent Dave Jones EEVBlog
>video nr 1561 ...
>
><https://www.youtube.com/watch?v=FKC6lnTKH-c>
>
>... he shows his USB powered variable bench power supply. At about 28:10
>the regulator schematic is shown. I am baffled why he uses two series
>pass transistors; one for current, one for voltage. I cannot recall ever
>seen the functionality split into two power transistors in series
>before. Is that laziness or brilliance? Does anyone have ideas about the
>design reasoning?
>
>Diode D4 in the voltage regulator does not inspire confidence.
>
>piglet

That's the craziest design I've ever seen. It must be a deliberate
parody.

John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
> On Wed, 30 Aug 2023 22:11:28 +0100, piglet <erichpwagner@hotmail.com>
> wrote:
>
>> Pardon a post about electronic design. In a recent Dave Jones EEVBlog
>> video nr 1561 ...
>>
>> <https://www.youtube.com/watch?v=FKC6lnTKH-c>
>>
>> ... he shows his USB powered variable bench power supply. At about 28:10
>> the regulator schematic is shown. I am baffled why he uses two series
>> pass transistors; one for current, one for voltage. I cannot recall ever
>> seen the functionality split into two power transistors in series
>> before. Is that laziness or brilliance? Does anyone have ideas about the
>> design reasoning?
>>
>> Diode D4 in the voltage regulator does not inspire confidence.
>>
>> piglet
>
> That's the craziest design I've ever seen. It must be a deliberate
> parody.
>
>

Disclaimer: I find EEVblog practically unwatchable, so I haven’t looked at
the schematic.

One reason to separate the current limit and voltage regulator functions is
to sharpen up the current limiter by putting it inside the voltage
regulator loop.

I commonly do that with LND150 depletion FETs in HV bias supplies for APDs
and SiPMs. They look like ~1k resistors below about 1.5 mA, which is enough
to hurt the gain linearity, but the feedback loop effectively knocks that
down to way under an ohm.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

On Thu, 31 Aug 2023 02:23:59 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
>> On Wed, 30 Aug 2023 22:11:28 +0100, piglet <erichpwagner@hotmail.com>
>> wrote:
>>
>>> Pardon a post about electronic design. In a recent Dave Jones EEVBlog
>>> video nr 1561 ...
>>>
>>> <https://www.youtube.com/watch?v=FKC6lnTKH-c>
>>>
>>> ... he shows his USB powered variable bench power supply. At about 28:10
>>> the regulator schematic is shown. I am baffled why he uses two series
>>> pass transistors; one for current, one for voltage. I cannot recall ever
>>> seen the functionality split into two power transistors in series
>>> before. Is that laziness or brilliance? Does anyone have ideas about the
>>> design reasoning?
>>>
>>> Diode D4 in the voltage regulator does not inspire confidence.
>>>
>>> piglet
>>
>> That's the craziest design I've ever seen. It must be a deliberate
>> parody.
>>
>>
>
>Disclaimer: I find EEVblog practically unwatchable, so I haven’t looked at
>the schematic.

It's a small lab power supply powered by USB-C. It has several
microprocessors, layers of isolators and switching regs and linear
regs, a custom enclosure with custom-machined connectors, a custom
planar transformer, a custom heat sink, a zillon layer PCB, and what
must be tens of KLOCs. It's apparently been in design for about 5
years.

Squeaky talks about it in an almost bearable tone.

Really, it's funny enough to have a look at. Skip the blather and look
at the schematic pages.

(I had hernia surgery today and am still goofy from the drugs, so this
sort of nonsense fit right in.)

>
>One reason to separate the current limit and voltage regulator functions is
>to sharpen up the current limiter by putting it inside the voltage
>regulator loop.
>
>I commonly do that with LND150 depletion FETs in HV bias supplies for APDs
>and SiPMs. They look like ~1k resistors below about 1.5 mA, which is enough
>to hurt the gain linearity, but the feedback loop effectively knocks that
>down to way under an ohm.
>
>Cheers
>
>Phil Hobbs

On 30/08/2023 22:40, Ricky wrote:
> On Wednesday, August 30, 2023 at 5:11:38 PM UTC-4, piglet wrote:
>> Pardon a post about electronic design. In a recent Dave Jones EEVBlog
>> video nr 1561 ...
>>
>> <https://www.youtube.com/watch?v=FKC6lnTKH-c>
>>
>> ... he shows his USB powered variable bench power supply. At about 28:10
>> the regulator schematic is shown. I am baffled why he uses two series
>> pass transistors; one for current, one for voltage. I cannot recall ever
>> seen the functionality split into two power transistors in series
>> before. Is that laziness or brilliance? Does anyone have ideas about the
>> design reasoning?
>>
>> Diode D4 in the voltage regulator does not inspire confidence.
>
> He has a forum. You could just go there and ask him. I'm sure he would love to discuss it with you.
>

Thanks, good call, I'd completely forgotten!

piglet

On 30/08/2023 23:50, Fred Bloggs wrote:
> On Wednesday, August 30, 2023 at 5:11:38 PM UTC-4, piglet wrote:
>> Pardon a post about electronic design. In a recent Dave Jones EEVBlog
>> video nr 1561 ...
>>
>> <https://www.youtube.com/watch?v=FKC6lnTKH-c>
>>
>> ... he shows his USB powered variable bench power supply. At about 28:10
>> the regulator schematic is shown. I am baffled why he uses two series
>> pass transistors; one for current, one for voltage. I cannot recall ever
>> seen the functionality split into two power transistors in series
>> before. Is that laziness or brilliance? Does anyone have ideas about the
>> design reasoning?
>
> They use similar in HP benchtops. It's necessary if you want a precision programmable current limit. Until it limits, it's just a saturated FET putting most of the voltage on the voltage regulation FET.
>
>>
>> Diode D4 in the voltage regulator does not inspire confidence.
>
> Note on schematic says D4 prevents interference by input diodes ( of error opamp ) on the voltage measurement, meaning at R22+ R23 junction. If I could read the pn of the op amp it would be clear, but it's not readable as is. Maybe it's some quasi-Norton amp. Whatever it is the input is acting on about a diode drop below the voltage at external (+) input.
>
> Schematic symbols of resistors look like inductors. FETs look like RJ-45 connectors.
>
>>
>> piglet

The opamp is OPA2180 zero drift/auto zero type with inverse parallel
input protection diodes. D4 looks mega kludgy - if it were mine I'd
investigate using a different opamp or taking the error signal from the
voltage follower used for metering. Still I guess in real life the
voltage drop error across D4 at nanoamp opamp input bias current is near
negligible?

piglet

On 31/08/2023 04:36, John Larkin wrote:
>
> (I had hernia surgery today and am still goofy from the drugs, so this
> sort of nonsense fit right in.)
>
>

Glad to have supplied some light relief!

piglet

On Thursday, August 31, 2023 at 7:03:29 AM UTC-4, piglet wrote:
> On 30/08/2023 23:50, Fred Bloggs wrote:
> > On Wednesday, August 30, 2023 at 5:11:38 PM UTC-4, piglet wrote:
> >> Pardon a post about electronic design. In a recent Dave Jones EEVBlog
> >> video nr 1561 ...
> >>
> >> <https://www.youtube.com/watch?v=FKC6lnTKH-c>
> >>
> >> ... he shows his USB powered variable bench power supply. At about 28:10
> >> the regulator schematic is shown. I am baffled why he uses two series
> >> pass transistors; one for current, one for voltage. I cannot recall ever
> >> seen the functionality split into two power transistors in series
> >> before. Is that laziness or brilliance? Does anyone have ideas about the
> >> design reasoning?
> >
> > They use similar in HP benchtops. It's necessary if you want a precision programmable current limit. Until it limits, it's just a saturated FET putting most of the voltage on the voltage regulation FET.
> >
> >>
> >> Diode D4 in the voltage regulator does not inspire confidence.
> >
> > Note on schematic says D4 prevents interference by input diodes ( of error opamp ) on the voltage measurement, meaning at R22+ R23 junction. If I could read the pn of the op amp it would be clear, but it's not readable as is. Maybe it's some quasi-Norton amp. Whatever it is the input is acting on about a diode drop below the voltage at external (+) input.
> >
> > Schematic symbols of resistors look like inductors. FETs look like RJ-45 connectors.
> >
> >>
> >> piglet
> The opamp is OPA2180 zero drift/auto zero type with inverse parallel
> input protection diodes. D4 looks mega kludgy - if it were mine I'd
> investigate using a different opamp or taking the error signal from the
> voltage follower used for metering. Still I guess in real life the
> voltage drop error across D4 at nanoamp opamp input bias current is near
> negligible?

None of what he has makes any sense, neither D4 nor that 2kR resistor. What's probably going on is he's hitting the Vset input with too large a step from his D/A, and that's causing the differential clamp diodes to conduct and produce screwy outputs until the loop recovers. He should limit his steps to say 50mV and allow settling time of 5x of what he's pre-measured before applying another one. Get rid of D4 and the 2k.

>
> piglet

piglet wrote:
> Ricky wrote:
>> piglet wrote:
>>> Pardon a post about electronic design. In a recent Dave Jones EEVBlog
>>> video nr 1561 ...
>>>
>>> <https://www.youtube.com/watch?v=FKC6lnTKH-c>
>>>
>>> ... he shows his USB powered variable bench power supply. At about 28:10
>>> the regulator schematic is shown. I am baffled why he uses two series
>>> pass transistors; one for current, one for voltage. I cannot recall ever
>>> seen the functionality split into two power transistors in series
>>> before. Is that laziness or brilliance? Does anyone have ideas about the
>>> design reasoning?
>>>
>>> Diode D4 in the voltage regulator does not inspire confidence.
>>
>> He has a forum. You could just go there and ask him. I'm sure he
>> would love to discuss it with you.
>
> Thanks, good call, I'd completely forgotten!

Yes, Ricky's suggestion is indeed excellent. And what do you know?
Someone at the forum already asked and Dave doesn't remember:

<https://www.eevblog.com/forum/blog/eevblog-1561-usupply-usb-power-supply-part-20/msg5033464/#msg5033464>

Regardless, it's my intention to find the time to digest the video
first, then post questions to Dave at the forum.

Danke,

--
Don, KB7RPU, https://www.qsl.net/kb7rpu
There was a young lady named Bright Whose speed was far faster than light;
She set out one day In a relative way And returned on the previous night.

On Thu, 31 Aug 2023 12:03:20 +0100, piglet <erichpwagner@hotmail.com>
wrote:

>On 30/08/2023 23:50, Fred Bloggs wrote:
>> On Wednesday, August 30, 2023 at 5:11:38?PM UTC-4, piglet wrote:
>>> Pardon a post about electronic design. In a recent Dave Jones EEVBlog
>>> video nr 1561 ...
>>>
>>> <https://www.youtube.com/watch?v=FKC6lnTKH-c>
>>>
>>> ... he shows his USB powered variable bench power supply. At about 28:10
>>> the regulator schematic is shown. I am baffled why he uses two series
>>> pass transistors; one for current, one for voltage. I cannot recall ever
>>> seen the functionality split into two power transistors in series
>>> before. Is that laziness or brilliance? Does anyone have ideas about the
>>> design reasoning?
>>
>> They use similar in HP benchtops. It's necessary if you want a precision programmable current limit. Until it limits, it's just a saturated FET putting most of the voltage on the voltage regulation FET.
>>
>>>
>>> Diode D4 in the voltage regulator does not inspire confidence.
>>
>> Note on schematic says D4 prevents interference by input diodes ( of error opamp ) on the voltage measurement, meaning at R22+ R23 junction. If I could read the pn of the op amp it would be clear, but it's not readable as is. Maybe it's some quasi-Norton amp. Whatever it is the input is acting on about a diode drop below the voltage at external (+) input.
>>
>> Schematic symbols of resistors look like inductors. FETs look like RJ-45 connectors.
>>
>>>
>>> piglet
>
>The opamp is OPA2180 zero drift/auto zero type with inverse parallel
>input protection diodes. D4 looks mega kludgy - if it were mine I'd
>investigate using a different opamp or taking the error signal from the
>voltage follower used for metering. Still I guess in real life the
>voltage drop error across D4 at nanoamp opamp input bias current is near
>negligible?
>
>piglet

Using a chopamp in that kluge is yet another absurdity.

On Thursday, August 31, 2023 at 9:56:46 AM UTC-7, John Larkin wrote:
> On Thu, 31 Aug 2023 12:03:20 +0100, piglet <erichp...@hotmail.com>
> wrote:

> >The opamp is OPA2180 zero drift/auto zero type with inverse parallel
> >input protection diodes. D4 looks mega kludgy - if it were mine I'd
> >investigate using a different opamp or taking the error signal from the
> >voltage follower used for metering. Still I guess in real life the
> >voltage drop error across D4 at nanoamp opamp input bias current is near
> >negligible?

> Using a chopamp in that kluge is yet another absurdity.

I must agree; there's THREE power pass transistors, one for the switch mode coarse regulator, one
for current, one for voltage, and you could easily limit the current at the switch mode node (there's
a switch-current-sense resistor there anyhow). The design has all the hallmarks of being
an exercise in using medium-scale-integration blocks, each with a single function.
That's how you end up needing two microprocessors to obey two instructions: supply-this-voltage
except limit-to-this-current.

One nice item, though, is worth mentioning: it displays BOTH the target-or-actual output voltage and output current
at the same time. One of my bench supplies has one-analog-meter-does-both; simpler, but a pain to use.

fredag den 1. september 2023 kl. 03.55.10 UTC+2 skrev whit3rd:
> On Thursday, August 31, 2023 at 9:56:46 AM UTC-7, John Larkin wrote:
> > On Thu, 31 Aug 2023 12:03:20 +0100, piglet <erichp...@hotmail.com>
> > wrote:
>
> > >The opamp is OPA2180 zero drift/auto zero type with inverse parallel
> > >input protection diodes. D4 looks mega kludgy - if it were mine I'd
> > >investigate using a different opamp or taking the error signal from the
> > >voltage follower used for metering. Still I guess in real life the
> > >voltage drop error across D4 at nanoamp opamp input bias current is near
> > >negligible?
> > Using a chopamp in that kluge is yet another absurdity.
> I must agree; there's THREE power pass transistors, one for the switch mode coarse regulator, one
> for current, one for voltage, and you could easily limit the current at the switch mode node (there's
> a switch-current-sense resistor there anyhow). The design has all the hallmarks of being
> an exercise in using medium-scale-integration blocks, each with a single function.
> That's how you end up needing two microprocessors to obey two instructions: supply-this-voltage
> except limit-to-this-current.

no it is not, one mcu is for an isolated USB interface, the other one for running the display/keypad/menu/supply

On Thu, 31 Aug 2023 12:05:31 +0100, piglet <erichpwagner@hotmail.com>
wrote:

>On 31/08/2023 04:36, John Larkin wrote:
>>
>> (I had hernia surgery today and am still goofy from the drugs, so this
>> sort of nonsense fit right in.)
>>
>>
>
>Glad to have supplied some light relief!
>
>piglet
>

Good quote, appropriate to that power supply:

It was the embodiment of the idea that perfection is not when there is
nothing left to add but when there is nothing left to take away.

Keith Houston in Empire of the Sum

John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
> On Thu, 31 Aug 2023 12:05:31 +0100, piglet <erichpwagner@hotmail.com>
> wrote:
>
>> On 31/08/2023 04:36, John Larkin wrote:
>>>
>>> (I had hernia surgery today and am still goofy from the drugs, so this
>>> sort of nonsense fit right in.)
>>>
>>>
>>
>> Glad to have supplied some light relief!
>>
>> piglet
>>
>
> Good quote, appropriate to that power supply:
>
>
> It was the embodiment of the idea that perfection is not when there is
> nothing left to add but when there is nothing left to take away.
>
> Keith Houston in Empire of the Sum
>
>
>
As the wise man said,

“All programs have bugs, and all programs can be made smaller. Therefore
all programs can be reduced to a single incorrect instruction.“

Cheers

Phil Hobbs

Phil Hobbs

--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

On Sat, 2 Sep 2023 19:25:50 -0000 (UTC), Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
>> On Thu, 31 Aug 2023 12:05:31 +0100, piglet <erichpwagner@hotmail.com>
>> wrote:
>>
>>> On 31/08/2023 04:36, John Larkin wrote:
>>>>
>>>> (I had hernia surgery today and am still goofy from the drugs, so this
>>>> sort of nonsense fit right in.)
>>>>
>>>>
>>>
>>> Glad to have supplied some light relief!
>>>
>>> piglet
>>>
>>
>> Good quote, appropriate to that power supply:
>>
>>
>> It was the embodiment of the idea that perfection is not when there is
>> nothing left to add but when there is nothing left to take away.
>>
>> Keith Houston in Empire of the Sum
>>
>>
>>
>As the wise man said,
>
>“All programs have bugs, and all programs can be made smaller. Therefore
>all programs can be reduced to a single incorrect instruction.“
>
>Cheers
>
>Phil Hobbs
>
>Phil Hobbs

PDP-11 had the RESET instruction. As in full hardware powerup-type
reset. Saved wear and tear on the power switch.

It also has the Land Mine instruction,

MOV -(PC), -(PC)

which copied itself one word below, and executed from there.

John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
> On Sat, 2 Sep 2023 19:25:50 -0000 (UTC), Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>
>> John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
>>> On Thu, 31 Aug 2023 12:05:31 +0100, piglet <erichpwagner@hotmail.com>
>>> wrote:
>>>
>>>> On 31/08/2023 04:36, John Larkin wrote:
>>>>>
>>>>> (I had hernia surgery today and am still goofy from the drugs, so this
>>>>> sort of nonsense fit right in.)
>>>>>
>>>>>
>>>>
>>>> Glad to have supplied some light relief!
>>>>
>>>> piglet
>>>>
>>>
>>> Good quote, appropriate to that power supply:
>>>
>>>
>>> It was the embodiment of the idea that perfection is not when there is
>>> nothing left to add but when there is nothing left to take away.
>>>
>>> Keith Houston in Empire of the Sum
>>>
>>>
>>>
>> As the wise man said,
>>
>> “All programs have bugs, and all programs can be made smaller. Therefore
>> all programs can be reduced to a single incorrect instruction.“
>>
>> Cheers
>>
>> Phil Hobbs
>>
>> Phil Hobbs
>
> PDP-11 had the RESET instruction. As in full hardware powerup-type
> reset. Saved wear and tear on the power switch.
>
> It also has the Land Mine instruction,
>
> MOV -(PC), -(PC)
>
> which copied itself one word below, and executed from there.
>
>

Before the vacuum-column tape transport was invented, early IBM tape drives
allegedly had an instruction SST, for “stop and stretch tape”.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

On 8/30/2023 11:36 PM, John Larkin wrote:

>> Disclaimer: I find EEVblog practically unwatchable, so I haven’t looked at
>> the schematic.
>
> It's a small lab power supply powered by USB-C. It has several
> microprocessors, layers of isolators and switching regs and linear
> regs, a custom enclosure with custom-machined connectors, a custom
> planar transformer, a custom heat sink, a zillon layer PCB, and what
> must be tens of KLOCs. It's apparently been in design for about 5
> years.

Maybe it was prototyped to help prototype other USB-C powered power
supplies:

<https://www.youtube.com/shorts/lSBx4f4yTFo>

> Squeaky talks about it in an almost bearable tone.
>
> Really, it's funny enough to have a look at. Skip the blather and look
> at the schematic pages.
>
> (I had hernia surgery today and am still goofy from the drugs, so this
> sort of nonsense fit right in.)

On Saturday, September 2, 2023 at 6:06:21 PM UTC-5, Phil Hobbs wrote:

> Before the vacuum-column tape transport was invented, early IBM tape drives
> allegedly had an instruction SST, for “stop and stretch tape”.
>
> Cheers
> Phil Hobbs
>
> --
> Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC /
> Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

What about the instruction HCF? I think it was "halt and catch fire".

On a sunny day (Sat, 02 Sep 2023 13:12:42 -0700) it happened John Larkin
<jlarkin@highlandSNIPMEtechnology.com> wrote in
<uh57fihhi4d8hc8u1k4o18o2qf79crilf9@4ax.com>:

>On Sat, 2 Sep 2023 19:25:50 -0000 (UTC), Phil Hobbs
><pcdhSpamMeSenseless@electrooptical.net> wrote:
>
>>John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
>>> On Thu, 31 Aug 2023 12:05:31 +0100, piglet <erichpwagner@hotmail.com>
>>> wrote:
>>>
>>>> On 31/08/2023 04:36, John Larkin wrote:
>>>>>
>>>>> (I had hernia surgery today and am still goofy from the drugs, so this
>>>>> sort of nonsense fit right in.)
>>>>>
>>>>>
>>>>
>>>> Glad to have supplied some light relief!
>>>>
>>>> piglet
>>>>
>>>
>>> Good quote, appropriate to that power supply:
>>>
>>>
>>> It was the embodiment of the idea that perfection is not when there is
>>> nothing left to add but when there is nothing left to take away.
>>>
>>> Keith Houston in Empire of the Sum
>>>
>>>
>>>
>>As the wise man said,
>>
>>�All programs have bugs, and all programs can be made smaller. Therefore
>>all programs can be reduced to a single incorrect instruction.�
>>
>>Cheers
>>
>>Phil Hobbs
>>
>>Phil Hobbs
>
>PDP-11 had the RESET instruction. As in full hardware powerup-type
>reset. Saved wear and tear on the power switch.
>
>It also has the Land Mine instruction,
>
>MOV -(PC), -(PC)
>
>which copied itself one word below, and executed from there.

In linux systems you just type, as root, 'poweroff' in a terminal.

As to starting anew with nothing:
s u d o rm -rf /*
remove spaces in 'sudo' (added those just to prevent poor creatures from doing a cut and paste)
as it will erase everything on your system.

And yes, as I am always root, I once typed rm * -rf by accident while in /
was quick to stop with ctrlC but hat to put back some X libraries...

Do not try this at home.. ;-)

On 2023-09-02 21:18, John Smiht wrote:
> On Saturday, September 2, 2023 at 6:06:21 PM UTC-5, Phil Hobbs wrote:
>
>> Before the vacuum-column tape transport was invented, early IBM tape drives
>> allegedly had an instruction SST, for “stop and stretch tape”.
>>
>> Cheers
>> Phil Hobbs

>
> What about the instruction HCF? I think it was "halt and catch fire".
>

From the Jargon File:
":HCF: /H·C·F/, n.

Mnemonic for `Halt and Catch Fire', any of several undocumented and
semi-mythical machine instructions with destructive side-effects,
supposedly included for test purposes on several well-known
architectures going as far back as the IBM 360. The MC6800
microprocessor was the first for which an HCF opcode became widely
known. This instruction caused the processor to {toggle} a subset of
the bus lines as rapidly as it could; in some configurations this
could actually cause lines to burn up. Compare {killer poke}."

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

On 2023-09-03 01:39, Jan Panteltje wrote:
> On a sunny day (Sat, 02 Sep 2023 13:12:42 -0700) it happened John Larkin
> <jlarkin@highlandSNIPMEtechnology.com> wrote in
> <uh57fihhi4d8hc8u1k4o18o2qf79crilf9@4ax.com>:
>
>> On Sat, 2 Sep 2023 19:25:50 -0000 (UTC), Phil Hobbs
>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>
>>> John Larkin <jlarkin@highlandSNIPMEtechnology.com> wrote:
>>>> On Thu, 31 Aug 2023 12:05:31 +0100, piglet <erichpwagner@hotmail.com>
>>>> wrote:
>>>>
>>>>> On 31/08/2023 04:36, John Larkin wrote:
>>>>>>
>>>>>> (I had hernia surgery today and am still goofy from the drugs, so this
>>>>>> sort of nonsense fit right in.)
>>>>>>
>>>>>>
>>>>>
>>>>> Glad to have supplied some light relief!
>>>>>
>>>>> piglet
>>>>>
>>>>
>>>> Good quote, appropriate to that power supply:
>>>>
>>>>
>>>> It was the embodiment of the idea that perfection is not when there is
>>>> nothing left to add but when there is nothing left to take away.
>>>>
>>>> Keith Houston in Empire of the Sum
>>>>
>>>>
>>>>
>>> As the wise man said,
>>>
>>> “All programs have bugs, and all programs can be made smaller. Therefore
>>> all programs can be reduced to a single incorrect instruction.“
>>>
>>> Cheers
>>>
>>> Phil Hobbs
>>>
>>> Phil Hobbs
>>
>> PDP-11 had the RESET instruction. As in full hardware powerup-type
>> reset. Saved wear and tear on the power switch.
>>
>> It also has the Land Mine instruction,
>>
>> MOV -(PC), -(PC)
>>
>> which copied itself one word below, and executed from there.
>
> In linux systems you just type, as root, 'poweroff' in a terminal.
>
> As to starting anew with nothing:
> s u d o rm -rf /*
> remove spaces in 'sudo' (added those just to prevent poor creatures from doing a cut and paste)
> as it will erase everything on your system.
>
> And yes, as I am always root, I once typed rm * -rf by accident while in /
> was quick to stop with ctrlC but hat to put back some X libraries...
>
> Do not try this at home.. ;-)
>
>
>
>
Even when not root, I always put the -rf last on the line, which works
fine and prevents fat fingers from causing destruction.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

On Sun, 3 Sep 2023 12:28:44 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>On 2023-09-02 21:18, John Smiht wrote:
>> On Saturday, September 2, 2023 at 6:06:21?PM UTC-5, Phil Hobbs wrote:
>>
>>> Before the vacuum-column tape transport was invented, early IBM tape drives
>>> allegedly had an instruction SST, for “stop and stretch tape”.
>>>
>>> Cheers
>>> Phil Hobbs
>
>>
>> What about the instruction HCF? I think it was "halt and catch fire".
>>
>
> From the Jargon File:
>":HCF: /H·C·F/, n.
>
> Mnemonic for `Halt and Catch Fire', any of several undocumented and
> semi-mythical machine instructions with destructive side-effects,
> supposedly included for test purposes on several well-known
> architectures going as far back as the IBM 360. The MC6800
> microprocessor was the first for which an HCF opcode became widely
> known. This instruction caused the processor to {toggle} a subset of
> the bus lines as rapidly as it could; in some configurations this
> could actually cause lines to burn up. Compare {killer poke}."
>
>Cheers
>
>Phil Hobbs

I used 6800s and never heard of that. They were depletion-load PMOS
parts, not CMOS, so overheating was unlikely.

The original PDP-11, the 11/20, was known to have a short program,
about 10 instructions, that would tease a metastability and quickly
hang the CPU. A power cycle would fix that. DEC machines in those days
were hairball async logic, a mess of gates and RC's and delay lines. I
don't think the PDP8/I or the 11/20 actually had a clock.