I have a Pi Zero W that runs headless as an SSH gateway here. It auto
connects to the Wifi and lets me SSH in to the home network etc. It's
more than up to the job in hand and uses barely any electricity so can
stay on 24/7.

It was running Debian 10 (or whatever the Pi version of that was called
Raspbian??) and I wanted to move to Debian 11 (PiOS ??). The preferred
way is to download the latest image and install that but that would be a
pain as there's lots of customisation been done. As I've successfully
updated 3 systems from 10 to 11 in situ so I thought I'd try it on the
Pi. It works like a dream (a bit slow) apart from one showstopper that
is easily fixed. The system has a very lightweight image, I'm not sure
now but think it was 2021-01-11-raspios-buster-armhf-lite.img
originally. SDcard was 8GB with about 5GB free.

Anyway having backed up the SDcard image...

sudo -s
apt update
apt upgrade
apt full-upgrade
apt --purge autoremove
reboot

When it reboots and you have logged in again...

sudo -s

Edit sources.list etc. in /etc/apt/* and change all the occurrences of
"buster" to "bullseye". There's a few files that need updating.

apt update
apt upgrade --without-new-pkgs
apt full-upgrade
apt --purge autoremove

Allow 30-45mins for the above. Depends on how big your installation was
and how fast the SDcard is.

At this point you would reboot and enjoy the fruits of your labours. But
you'll find deep sadness if you do. The upgrade borks dhcpcd5 and you
have no DHCP client so there is no networking. I couldn't SSH in :-( Of
course this is a real pain on a headless machine. I don't have a serial
console for this Pi Zero W so I put the card in a Pi A+ that does and I
could see the SDcard booted to a login prompt. My account and password
was there and the config files looked OK. I had a cup of tea and
realised I had a Mini HDMI to HDMI adapter and watching the boot
messages I could see DHCP errors. A bit of Googling found

https://forums.raspberrypi.com/viewtopic.php?t=320383

Anyway, the fix is to edit
/etc/systemd/system/dhcpcd.service.d/wait.conf and change

ExecStart=/usr/lib/dhcpcd5/dhcpcd -q -w
to
ExecStart=/usr/sbin/dhcpcd -q -w

Rebooting after you have done this and the system will come up all fine
and dandy. Of course I had to fanny about to find this out and edit the
file on another system. If it wasn't for this then the upgrade process,
whilst a bit slow, would be as painless as it is on other Debian derived
systems.

Info on this is out there. I'm hoping this might be useful to someone
who wants to do this and doesn't want to have to fix it afterwards ;-)

Andy

YMMV

On a sunny day (Sat, 29 Oct 2022 22:13:03 +0100) it happened mm0fmf
<none@invalid.com> wrote in <tjk510$3mmgj$1@dont-email.me>:

>I have a Pi Zero W that runs headless as an SSH gateway here. It auto
>connects to the Wifi and lets me SSH in to the home network etc. It's
>more than up to the job in hand and uses barely any electricity so can
>stay on 24/7.

The old wisdom was always:
"If it works do not fix it"
I have a Pi running 24/7 where
uname -a
says 2013

So say 20 years

Sure there may arise security issues,
but that old one is not even connected to the net and does not use WiFi
Next you have to put a new engine in your car every year????

**
But there are more dark clouds with Linux coming
Linus (the creator of Linux) is now considering dropping 486 support...
I still have 2 PCs with those processors, and use those on a regular basis.
So upgrades MAY become fatal.
**

And that rathead dhcpcd or whatever should never have existed.

Maybe I just write my own OS and be done with it
wrote a multitasker for Z80 long time ago
Few lines, world has bloated after that.
Bloat sells it seems.

Many if not most things can be done with a 2$ micro chip.

mm0fmf <none@invalid.com> wrote:
> It was running Debian 10 (or whatever the Pi version of that was called
> Raspbian??) and I wanted to move to Debian 11 (PiOS ??).
> [...]
> Allow 30-45mins for the above. Depends on how big your installation was
> and how fast the SDcard is.
> [...]
> Anyway, the fix is to edit
> /etc/systemd/system/dhcpcd.service.d/wait.conf and change
>
> ExecStart=/usr/lib/dhcpcd5/dhcpcd -q -w
> to
> ExecStart=/usr/sbin/dhcpcd -q -w

Useful, thanks. But yeah, I do always go with a completely new image on
RasPis. I sorta know my customisations by heart now, and just in case I
always keep a description of them on every Pi. So I spend that half hour
waiting time doing that. An alternative would be automation with e.g.
Ansible, but meh.

On Sun, 30 Oct 2022 06:01:00 GMT
Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:

> Maybe I just write my own OS and be done with it
> wrote a multitasker for Z80 long time ago
> Few lines, world has bloated after that.

Be careful!

Linux started because Linus Torvalds had a neat idea for task
switching on a 386 - just a few lines of code that grew into a kernel and
met GNU looking for a kernel.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

On 30/10/2022 06:19, A. Dumas wrote:
> and just in case I
> always keep a description of them on every Pi

There's the rub. I did the customisations on the fly and they evolved
over some time and I *didn't* make a note... very poor. I do the same
kind of stuff at work on VMs and simulations for customer designs
(custom kernels and setups) and there's plenty of such notes in repos,
Jira tickets and OneNote pages but I didn't do it at home. It's a
classic case of the cobbler's children have the worst shoes!

On a sunny day (Sun, 30 Oct 2022 07:15:22 +0000) it happened Ahem A Rivet's
Shot <steveo@eircom.net> wrote in
<20221030071522.b9291fd48fc7adc8392c4630@eircom.net>:

>On Sun, 30 Oct 2022 06:01:00 GMT
>Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:
>
>> Maybe I just write my own OS and be done with it
>> wrote a multitasker for Z80 long time ago
>> Few lines, world has bloated after that.
>
> Be careful!
>
> Linux started because Linus Torvalds had a neat idea for task
>switching on a 386 - just a few lines of code that grew into a kernel and
>met GNU looking for a kernel.

I know, I have one very old distro, SLS Linux, from 1998, on a floppy..
installed it back then and never went back to MS windows...
And my other system was a CP/M system compatible (to some point) with a Kaypro 2,
as I did not have CP/M back then and wanted to try some software from the CP/M user club,
I modified a Sinclair ZX81 and wrote my own CP/M clone:
http://panteltje.com/panteltje/z80/index.html

The OS:
http://panteltje.com/panteltje/z80/system14/index.html

The hardware (designed it too):
http://panteltje.com/panteltje/z80/system14/diagrams/index.html

People are still using that Z80 disassembler it seems, from email feedback I got a few years ago.

It is all not so hard, bit of ASM,
http://panteltje.com/panteltje/newsflex/download.html

But like I said: a small micro can do most things:
http://panteltje.com/panteltje/pic/index.html
US went to the moon and back with less computer power.

I think US now wants to 'prevent' China from having a 7 nm chip factory..
US mafia.
Electric cars, nothing will run anymore but for the old diesel after the chip wars..

On Sun, 30 Oct 2022 08:00:05 GMT
Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:

> wrote my own CP/M clone:
> http://panteltje.com/panteltje/z80/index.html
>
> The OS:
> http://panteltje.com/panteltje/z80/system14/index.html
>
> The hardware (designed it too):
> http://panteltje.com/panteltje/z80/system14/diagrams/index.html

I managed to get paid for doing both of those things in 1982, my
first job out of college.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

On a sunny day (Sun, 30 Oct 2022 11:31:41 +0000) it happened Ahem A Rivet's
Shot <steveo@eircom.net> wrote in
<20221030113141.985d665c8a477c45d4cca895@eircom.net>:

>On Sun, 30 Oct 2022 08:00:05 GMT
>Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:
>
>> wrote my own CP/M clone:
>> http://panteltje.com/panteltje/z80/index.html
>>
>> The OS:
>> http://panteltje.com/panteltje/z80/system14/index.html
>>
>> The hardware (designed it too):
>> http://panteltje.com/panteltje/z80/system14/diagrams/index.html
>
> I managed to get paid for doing both of those things in 1982, my
>first job out of college.

Yea, in the eighties I worked for a company that had close relations with IBM
and was designing for example ISA cards that did all sort of things for in the first PCs.
I remember we discussed possibly moving to Unix...
Designed some sort of sound card too, code in x86 asm.. and a vector processing card.

But that Z80 thing I designed at home was actually faster than the old IBM PC, as mine had a ramdisk :-)
You would load the floppy to ramdisk at startup, and everything would work from there
no mere seek times... sectors read in a flash.
Its all in those circuits, I added the command "floppytord" to the OS
it would copy the whole floppy to ramdisk..
All in the evening tinkering..

My first job was 1967 designing things for the army, navy and power stations.. not my thing so
in 1968 I went to work for the national TV station, got the job as I already had designed and build my
own (vidicon) camera... then 6 month training in broadcast technology (much like the BBC in the UK)
worked there many years, then left and went all over the world doing all sort of things
then came back and worked at some particle accelerator, then started my own company.. then that PC thing...
I am curious by nature... worked in the lab of a big university hospital too,
all sorts of cool stuff. hey even did some thing for ESA.
Somebody recently told me I should write a book about it all... LOL who knows...
Help educate this generation?
If a WW3 nuke war happens and a big EMP destroys all smartphones, then knowing how to send an SOS with the
simplest means ... (I am a radio ham too) other than with smoke signals... bit of knowhow may help.

getting carried away obviously...
:-)

On Sun, 30 Oct 2022 12:33:29 GMT
Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:

> If a WW3 nuke war happens and a big EMP destroys all smartphones, then
> knowing how to send an SOS with the simplest means ... (I am a radio ham
> too) other than with smoke signals... bit of knowhow may help.

I'm pretty sure I could manage a spark gap transmitter with nothing
electronic available (my morse is *very* rusty though) - for a crystal
receiver I'd need a good high impedance earpiece which would be trickier.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

On a sunny day (Sun, 30 Oct 2022 13:23:15 +0000) it happened Ahem A Rivet's
Shot <steveo@eircom.net> wrote in
<20221030132315.9aeeb170174a5222d19a01bc@eircom.net>:

>On Sun, 30 Oct 2022 12:33:29 GMT
>Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:
>
>> If a WW3 nuke war happens and a big EMP destroys all smartphones, then
>> knowing how to send an SOS with the simplest means ... (I am a radio ham
>> too) other than with smoke signals... bit of knowhow may help.
>
> I'm pretty sure I could manage a spark gap transmitter with nothing
>electronic available (my morse is *very* rusty though) - for a crystal
>receiver I'd need a good high impedance earpiece which would be trickier.

I had one of those crystal earphones once in the late fifties or early sixties,
seen those on ebay,
Spark transmitter I have tried, worked, used an old car ignition coil :-)
local radio ham got very upset..

crystal radios, tune with a ferrite rod shifting in the coil

Now I have a nice Tecsun long wave to short wave range AM SSB plus FM receiver,
Will it survive the EMP? Dunno.
No tubes left anymore but that could be an option.
Once build a 250 Watt linear with a PE/100 tube.
250 Ah lifepo4 battery pack and a pure sinewave converter plus solar panels I have here standby.
And the other usual transceiver radio stuff.

Oh and some digital TV transmit stuff that uses a Raspberry too:
http://panteltje.com/panteltje/raspberry_pi_dvb-s_transmitter/

Many more projects:
http://panteltje.com/panteltje/newsflex/download.html

And not everything is on the website

On Sun, 30 Oct 2022 16:23:15 GMT, Jan Panteltje wrote:

> On a sunny day (Sun, 30 Oct 2022 13:23:15 +0000) it happened Ahem A
> Rivet's Shot <steveo@eircom.net> wrote in
> <20221030132315.9aeeb170174a5222d19a01bc@eircom.net>:
>
>>On Sun, 30 Oct 2022 12:33:29 GMT Jan Panteltje
>><pNaonStpealmtje@yahoo.com> wrote:
>>
>>> If a WW3 nuke war happens and a big EMP destroys all smartphones, then
>>> knowing how to send an SOS with the simplest means ... (I am a radio
>>> ham too) other than with smoke signals... bit of knowhow may help.

From what I've read the EMP would take out rather more than smartphones.

> I had one of those crystal earphones once in the late fifties or early
> sixties. crystal radios, tune with a ferrite rod shifting in the coil
>
I built a broadcast AM crystal set when I was about 11 - hand-wound coil
on a cardboard tube former, but mine had a multi-blage rotary capacitor
for tuning and a glass-encapsulated germanium diode.

I forget where the earphones came from but they were certainly high
impedance. IIRC the sound quality was surprisingly good and, of course, no
battery needed. This was a year or two before portable transistor radios
first appeared -and before individually packaged unijunction germanium
transistors appeared (think OC-72 single junction devices in metal of
glass packaging).

No suitable headphones? Easily replaced by an 80mm speaker plus a small
amp (LM358 + 470m pot + 4.7M feedback resistor or some equivalent IC amp)
and a battery or small solar panel for power.
> seen those on ebay,
> Spark transmitter I have tried, worked, used an old car ignition coil
> :-) local radio ham got very upset..
>
Never tried that, but did enjoy playing with WS48 sets while at secondary
school: mt school had a compulsory cadet corps but joining the Signals
Platoon got some of us out of a lot of square bashing.

The WS48 was a battery-operated WW2 infantry backpack radio:

http://www.radiomilitari.com/ws48.html

FWIW, and to get back (partly) on topic for this 'ere newsgroup the first
computer I saw (and programmed) was an Elliott 503 scientific computer.
8 track paper tape input, 8 track tape or fast 132 column drum printer
output. It was about 4 wardrobe-size grey cabinets plus a control console.
Its logic built using discrete transistors. It had ferrite core memory (39
bit words) and packed two instructions per word. It was programmed in
Algol 60. Special feature: it implemented hardware floating point
arithmetic which was slightly faster then its integer operations.

--

Martin | martin at
Gregorie | gregorie dot org

A. Dumas <alexandre@dumas.fr.invalid> wrote:
>
> Useful, thanks. But yeah, I do always go with a completely new image on
> RasPis. I sorta know my customisations by heart now, and just in case I
> always keep a description of them on every Pi. So I spend that half hour
> waiting time doing that. An alternative would be automation with e.g.
> Ansible, but meh.

The first time you upgrade, you discover all the mistakes that you
made in your first notes. The second time you upgrade, you discover
all the mistakes that you made fixing the mistakes in your first
notes. The third time you upgrade, the software has changed and it
doesn't work that way anymore.

--
__ __
#_ < |\| |< _#

On 2022-10-30, Martin Gregorie <martin@mydomain.invalid> wrote:

> On Sun, 30 Oct 2022 16:23:15 GMT, Jan Panteltje wrote:
>
>> I had one of those crystal earphones once in the late fifties or early
>> sixties. crystal radios, tune with a ferrite rod shifting in the coil

I had one of those crystal earphones too. I could plug it directl into
the preamp output of my tape recorder. A regular earphone plugged into
the speaker output switched to the opposite channel where the crystal
earphone gave me stereo sound.

> I built a broadcast AM crystal set when I was about 11 - hand-wound coil
> on a cardboard tube former, but mine had a multi-blage rotary capacitor
> for tuning and a glass-encapsulated germanium diode.

That's the same as the set I built. I used an old telephone handset
to listen to it. That worked for the local AM station. Then the
next-closest station upgraded to 50 kilowatts, which came in loud
and clear over half the dial (my selectivity wasn't that great).

I later added a tube to it, then added another coil to make it
regenerative (and prone to oscillation if you turned the gain
up too high).

I once saw (but never built) a schematic for a set with a transistor
amplifier which was powered by a second tuner which you'd set to the
strongest local station - no batteries or external power required.

--
/~\ Charlie Gibbs | Microsoft is a dictatorship.
\ / <cgibbs@kltpzyxm.invalid> | Apple is a cult.
X I'm really at ac.dekanfrus | Linux is anarchy.
/ \ if you read it the right way. | Pick your poison.

On a sunny day (Sun, 30 Oct 2022 17:49:32 -0000 (UTC)) it happened Martin
Gregorie <martin@mydomain.invalid> wrote in <tjmdfc$2oess$1@dont-email.me>:

>On Sun, 30 Oct 2022 16:23:15 GMT, Jan Panteltje wrote:
>
>> On a sunny day (Sun, 30 Oct 2022 13:23:15 +0000) it happened Ahem A
>> Rivet's Shot <steveo@eircom.net> wrote in
>> <20221030132315.9aeeb170174a5222d19a01bc@eircom.net>:
>>
>>>On Sun, 30 Oct 2022 12:33:29 GMT Jan Panteltje
>>><pNaonStpealmtje@yahoo.com> wrote:
>>>
>>>> If a WW3 nuke war happens and a big EMP destroys all smartphones, then
>>>> knowing how to send an SOS with the simplest means ... (I am a radio
>>>> ham too) other than with smoke signals... bit of knowhow may help.
>
>From what I've read the EMP would take out rather more than smartphones.

Yes, especially high altitude nukes would take out satellites
I have read the 'telstar' satellite was killed by a US high altitude nuke test,
But lots of other thing will go, cellphone towers, airplane electronics
(helis could crash), what not.
No more electrickety! all those power lines and the related control electronics out.

>> I had one of those crystal earphones once in the late fifties or early
>> sixties. crystal radios, tune with a ferrite rod shifting in the coil
>>
>I built a broadcast AM crystal set when I was about 11 - hand-wound coil
>on a cardboard tube former, but mine had a multi-blage rotary capacitor
>for tuning and a glass-encapsulated germanium diode.

Ah yes, 500 pF tuning caps, I still have one:
http://panteltje.com/pub/testing_the_20_meter_inductive_loop_antenna_IMG_4536.JPG

>I forget where the earphones came from but they were certainly high
>impedance. IIRC the sound quality was surprisingly good and, of course, no
>battery needed. This was a year or two before portable transistor radios
>first appeared -and before individually packaged unijunction germanium
>transistors appeared (think OC-72 single junction devices in metal of
>glass packaging).

I used the OA79 Ge diode
worked with battery powered tubes (1.5 V heater voltage) DL92?
One day transistors came on the market, OC13 was my first transistor.

>No suitable headphones? Easily replaced by an 80mm speaker plus a small
>amp (LM358 + 470m pot + 4.7M feedback resistor or some equivalent IC amp)
>and a battery or small solar panel for power.

Long before integrated audio amps I build things with AC127 I think it was
singend ended pushpull amps, later with 3055 for more power!
But before that I build an amplifiwr for the school band (guitar) with tubes..
>> seen those on ebay,
>> Spark transmitter I have tried, worked, used an old car ignition coil
>> :-) local radio ham got very upset..
>>
>Never tried that, but did enjoy playing with WS48 sets while at secondary
>school: mt school had a compulsory cadet corps but joining the Signals
>Platoon got some of us out of a lot of square bashing.

I once bought a '31 set' in the army surplus:
https://www.radiomuseum.org/r/mil_gb_wireless_set_no31.html
got it working and said 'hello' on some frequency
Some mil guy asked me who I was ..oops, switched it off.

>The WS48 was a battery-operated WW2 infantry backpack radio:
>
>http://www.radiomilitari.com/ws48.html
>
>FWIW, and to get back (partly) on topic for this 'ere newsgroup the first
>computer I saw (and programmed) was an Elliott 503 scientific computer.
>8 track paper tape input, 8 track tape or fast 132 column drum printer
>output. It was about 4 wardrobe-size grey cabinets plus a control console.
>Its logic built using discrete transistors. It had ferrite core memory (39
>bit words) and packed two instructions per word. It was programmed in
>Algol 60. Special feature: it implemented hardware floating point
>arithmetic which was slightly faster then its integer operations.

I did design some equipment that had some programmable part,
my first experiments with a programmable machine, was part of a bigger project,
But .. my first computer was a Sinclair ZX80
Then I bought the book "Microprocessor interfacing techniques' by Rodnay Zaks and things took of from there
interfacing that ZX80...
https://www.amazon.com/Microprocessor-Interfacing-Techniques-Rodnay-Zaks/dp/0895880296

On Mon, 31 Oct 2022 05:37:22 GMT, Jan Panteltje wrote:

> Yes, especially high altitude nukes would take out satellites I have
> read the 'telstar' satellite was killed by a US high altitude nuke test,
> But lots of other thing will go, cellphone towers, airplane electronics
> (helis could crash), what not.
>
Seems that, according to Wikipedia anyway, it took two high altitude nukes
(one US, one Soviet) plus a burst of solar radiation to kill Telstar 1.
> But .. my first computer was a Sinclair ZX80 Then I bought the book
> "Microprocessor interfacing techniques' by Rodnay Zaks and things took
> of from there interfacing that ZX80...
> https://www.amazon.com/Microprocessor-Interfacing-Techniques-Rodnay-
> Zaks/dp/0895880296
>
After the Elliott and graduation I joined ICL and learnt first 1900
assembler and then COBOL, followed by various OSen up to and including
George3, multi-user, multitasking OS with a hierarchical directory
structure on a 32K 1903 (24 bit words) in 1970.

My first personal system was 6809-based (32KB RAM, 2 x 5.25" disks, 16 x
64 memory mapped display, on an SS-50 bus, with the FLEX-09 'OS'. I
bought the whole thing as a kit, soldered chips onto boards and debugged
it with a logic probe and multimeter. Since by then (1979) I was using 80
x 24 green screens at work I soon swapped the display board for a 24 x 80
one (also self-assembled and using a 2K EPROM as character generator.)
Rewrote the boot EPROM to suit.

--

Martin | martin at
Gregorie | gregorie dot org

On a sunny day (Mon, 31 Oct 2022 13:56:17 -0000 (UTC)) it happened Martin
Gregorie <martin@mydomain.invalid> wrote in <tjok61$gl9g$1@dont-email.me>:

>On Mon, 31 Oct 2022 05:37:22 GMT, Jan Panteltje wrote:
>
>> Yes, especially high altitude nukes would take out satellites I have
>> read the 'telstar' satellite was killed by a US high altitude nuke test,
>> But lots of other thing will go, cellphone towers, airplane electronics
>> (helis could crash), what not.
>>
>Seems that, according to Wikipedia anyway, it took two high altitude nukes
>(one US, one Soviet) plus a burst of solar radiation to kill Telstar 1.
>
>> But .. my first computer was a Sinclair ZX80 Then I bought the book
>> "Microprocessor interfacing techniques' by Rodnay Zaks and things took
>> of from there interfacing that ZX80...
>> https://www.amazon.com/Microprocessor-Interfacing-Techniques-Rodnay-
>> Zaks/dp/0895880296
>>
>After the Elliott and graduation I joined ICL and learnt first 1900
>assembler and then COBOL, followed by various OSen up to and including
>George3, multi-user, multitasking OS with a hierarchical directory
>structure on a 32K 1903 (24 bit words) in 1970.
>
>My first personal system was 6809-based (32KB RAM, 2 x 5.25" disks, 16 x
>64 memory mapped display, on an SS-50 bus, with the FLEX-09 'OS'. I
>bought the whole thing as a kit, soldered chips onto boards and debugged
>it with a logic probe and multimeter. Since by then (1979) I was using 80
>x 24 green screens at work I soon swapped the display board for a 24 x 80
>one (also self-assembled and using a 2K EPROM as character generator.)
>Rewrote the boot EPROM to suit.

Yes, after the ZX80 I bought a ZX81 and a 64 kB memory extention module
and then first thing I build was an EPROM programmer,,
and used it for a graphics card:
http://panteltje.com/pub/z80/graphics_card_top.jpg
note the EPROM bottom left with character generator also 80x24
handwired, characters drawn bit by bit..
http://panteltje.com/pub/z80/graphics_card_bottom.jpg

then the ZX81 was no longer part of it as I used my own processor card
http://panteltje.com/pub/s/z80_board.jpg
not very sharp but only picture could find
wiring now on the backside;
http://panteltje.com/pub/s/wiring1.jpg
then many other boards like that... floppy controller, modem, soundcard, I/O card, etc etc
http://panteltje.com/pub/z80/soundcard_top.jpg
In 1979 I designed and build a video digitizer and showed it at work ..
I *knew* there was a path to world wide digital video, was before mpeg compression
that changed a lot of things...

On Mon, 31 Oct 2022 14:53:52 GMT
Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:

> Yes, after the ZX80 I bought a ZX81

Ah the memories - the ZX81 was the originally intended product, the
ZX80 was essentially the prototype but (like everyone at the time) Sinclair
was having trouble getting the Ferranti ULAs to do what they said they
would - so just like Grundy with the Newbrain he shipped the prototype, but
unlike Grundy he followed it up with the real thing.

The connection is that both started life as the same government
backed project that wound up producing the BBC micro which inspired the Pi.

--
Steve O'Hara-Smith
Odds and Ends at http://www.sohara.org/

Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:
> On a sunny day (Sun, 30 Oct 2022 13:23:15 +0000) it happened Ahem A Rivet's
> Shot <steveo@eircom.net> wrote in
> <20221030132315.9aeeb170174a5222d19a01bc@eircom.net>:
>
>>On Sun, 30 Oct 2022 12:33:29 GMT
>>Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:
>>
>>> If a WW3 nuke war happens and a big EMP destroys all smartphones, then
>>> knowing how to send an SOS with the simplest means ... (I am a radio ham
>>> too) other than with smoke signals... bit of knowhow may help.
>>
>> I'm pretty sure I could manage a spark gap transmitter with nothing
>>electronic available (my morse is *very* rusty though) - for a crystal
>>receiver I'd need a good high impedance earpiece which would be trickier.
>
> I had one of those crystal earphones once in the late fifties or early sixties,
> seen those on ebay,
> Spark transmitter I have tried, worked, used an old car ignition coil :-)
> local radio ham got very upset..

I had one of those Radio Shack 150-project electronics kits back in the day.
One of the projects within was a spark-gap transmitter, in which a relay was
wired up with the normally-closed contacts set to cut power to the coil when
energized. I don't know how long it would've lasted before the relay
contacts were shot, but it succeeded at making detectable noise over most of
the AM band (though not to the extent that it interfered with broadcasters).

--
_/_
/ v \ Scott Alfter (remove the obvious to send mail)
(IIGS( https://alfter.us/ Top-posting!
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On a sunny day (Mon, 31 Oct 2022 17:20:27 GMT) it happened
scott@alfter.diespammersdie.us wrote in <vtT7L.649243$6Il8.431568@fx14.iad>:

>Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:
>> On a sunny day (Sun, 30 Oct 2022 13:23:15 +0000) it happened Ahem A Rivet's
>> Shot <steveo@eircom.net> wrote in
>> <20221030132315.9aeeb170174a5222d19a01bc@eircom.net>:
>>
>>>On Sun, 30 Oct 2022 12:33:29 GMT
>>>Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:
>>>
>>>> If a WW3 nuke war happens and a big EMP destroys all smartphones, then
>>>> knowing how to send an SOS with the simplest means ... (I am a radio ham
>>>> too) other than with smoke signals... bit of knowhow may help.
>>>
>>> I'm pretty sure I could manage a spark gap transmitter with nothing
>>>electronic available (my morse is *very* rusty though) - for a crystal
>>>receiver I'd need a good high impedance earpiece which would be trickier.
>>
>> I had one of those crystal earphones once in the late fifties or early sixties,
>> seen those on ebay,
>> Spark transmitter I have tried, worked, used an old car ignition coil :-)
>> local radio ham got very upset..
>
>I had one of those Radio Shack 150-project electronics kits back in the day.
>One of the projects within was a spark-gap transmitter, in which a relay was
>wired up with the normally-closed contacts set to cut power to the coil when
>energized. I don't know how long it would've lasted before the relay
>contacts were shot, but it succeeded at making detectable noise over most of
>the AM band (though not to the extent that it interfered with broadcasters).

Ha, these days most wallwarts wil do that!

On 2022-11-01, Jan Panteltje <pNaonStpealmtje@yahoo.com> wrote:

> On a sunny day (Mon, 31 Oct 2022 17:20:27 GMT) it happened
>
>> I had one of those Radio Shack 150-project electronics kits back in the day.
>> One of the projects within was a spark-gap transmitter, in which a relay was
>> wired up with the normally-closed contacts set to cut power to the coil when
>> energized. I don't know how long it would've lasted before the relay
>> contacts were shot, but it succeeded at making detectable noise over most of
>> the AM band (though not to the extent that it interfered with broadcasters).
>
> Ha, these days most wallwarts wil do that!

The cheap ones, anyway. I have one of those USB charging adaptors that
plugs into a car cigarette lighter that wipes out a weak FM station.

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