On 23/09/2021 13:27, Java Jive wrote:
> On 23/09/2021 10:57, Bob Latham wrote:
>>
>> Why do I know this, I've not touched one this century and yet I can't
>> remember what I had to tea last night.:-)
>
> That's just the way old people's memories work, and it poses an
> interesting evolutionary question. Why should old people have evolved
> to remember best what happened in their distant childhood and youth?
>
> Well, I suspect it works like this: Consider some obscure tribe living
> by subsistence, there's a bad drought, and you're an old member of the
> tribe, almost the last surviving member of your generation, who because
> of your old age is dependent on younger people for your subsistence.
> There would be zilch evolutionary advantage in their keeping you alive
> if all you could remember was what happened yesterday, because everyone
> else can remember that too, and probably better, but if you can remember
> that during a similar drought in your childhood your grandfather led
> them to a distant watering hole several days' walk to the north west,
> and thereby saved them, that is much more useful information to the
> survival of all, and thereby of you.
>

Nothing to do with evolution because as old fogies we're well past
the breeding stage!

On 23/09/2021 16:24, gareth evans wrote:
>
> On 23/09/2021 13:27, Java Jive wrote:
>>
>> That's just the way old people's memories work, and it poses an
>> interesting evolutionary question.  Why should old people have evolved
>> to remember best what happened in their distant childhood and youth?
>>
>> Well, I suspect it works like this:  Consider some obscure tribe living
>> by subsistence, there's a bad drought, and you're an old member of the
>> tribe, almost the last surviving member of your generation, who because
>> of your old age is dependent on younger people for your subsistence.
>> There would be zilch evolutionary advantage in their keeping you alive
>> if all you could remember was what happened yesterday, because everyone
>> else can remember that too, and probably better, but if you can remember
>> that during a similar drought in your childhood your grandfather led
>> them to a distant watering hole several days' walk to the north west,
>> and thereby saved them, that is much more useful information to the
>> survival of all, and thereby of you.
>
> Nothing to do with evolution because as old fogies we're well past
> the breeding stage!

Well of course that's part of the conundrum, but given two random
genetic modifications in a population, one of which happens to favour
old people's recollections of their early life, and the other either
doesn't, or perhaps favours old people remembering only what happened
yesterday, one would expect that a population with the former might fare
better over the long term than a population with the latter. Evolution
is driven by the survival of the fittest *genes*, which is not always
the same thing as the survival of the fittest individual carrier of
those genes.

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

On 23/09/2021 14:20, Jeff Gaines wrote:
> On 23/09/2021 in message <sihrrh$1q3h$1@gioia.aioe.org> Java Jive wrote:
>
>> but if you can remember that during a similar drought in your
>> childhood your grandfather led them to a distant watering hole several
>> days' walk to the north west, and thereby saved them, that is much
>> more useful information to the survival of all, and thereby of you.
>
> But once you've told everybody else where the water is they can do you
> in and save water and food :-)

But who knows what else you might be able to remember that might be useful?

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

On 23/09/2021 13:10, Java Jive wrote:
> On 22/09/2021 10:15, Jim Lesurf wrote:
>> In article <596f71819bcharles@candehope.me.uk>, charles
>> <charles@candehope.me.uk> wrote:
>>
>>> I saw the letter that Sinclair wrote to the BBC on this subject. He said
>>> the BBC spcoification for the BBC Micro, and in particular BBC Basic,
>>> was totally wrong. He would, however, allow the BBC to put their name on
>>> one of his machines. I, also, knew the chap who got paid a significant
>>> sum by Sinclair to make BBC Baisic fit his ZX81 (I think) laptop.
>>
>> Uncle Clive had some excellent ideas, but suffered from a tendency to
>> impliment them poorly. e.g. his liking for 'cheap' components to save
>> money... leading to product unreliability or bothersome behaviour.[1]
>
> Yes, very much so.  I remember buying one of the first pocket
> calculators, a Sinclair, which after a short while became useless
> because its on/off switch was unreliable.  It would turn off while you
> were doing a calculation.  Some while later I bought one of the first
> programmable calculators, again a Sinclair: "Wonderful!", I thought,  "I
> can program it once, and then just key in the results of a physics
> experiment one by one and read off the result to enter into the table
> and plot on the graph!"  Useless, same problem!

That was my experience of the Sinclair Cambridge. Either the switch or
the battery terminals failed.

Nowadays similarly with the cheap electric toothbrushes I buy - it's
always the switch that fails.

--
Max Demian

In message <59706885ffbob@sick-of-spam.invalid>, Bob Latham
<bob@sick-of-spam.invalid> writes
>In article <UTuvT2APaEThFwkz@jhall_nospamxx.co.uk>,
> John Hall <john_nospam@jhall.co.uk> wrote:
>
>
>> IIRC, the biggest difference was in how the competitors allocated
>> their 64KB memory. The Acorn BBC B used 32KB for its Basic, which
>> meant it was a better Basic than Clive Sinclair's, which used only
>> 16KB. Of course the corollary of that was that the BBC machine had
>> only 32KB left for the user's program, compared to the Spectrum's
>> 48KB.
>
>At the top of memory the operating system had slightly less than 16K
>of rom space. A bit cut out for Fred, Jim and Sheila I/O interfaces.
>
>Next down the BBC basic rom like the other language and tool roms was
>16K but other roms could be swapped in sideways.
>
>The remaining 32k was ram
>Screen at the top, of variable size depending on colours and res.
>Next down was the user's code area.
>Then OS workspace/language workspace.
>The stack.
>and last of all, zero page.
>
>Why do I know this, I've not touched one this century

Your recall is a lot better than mine. I stopped using my BBC B when I
got an Amstrad 1640 in 1985 or 1986.

> and yet I can't
>remember what I had to tea last night. :-)
>

I have that problem too. :)
--
John Hall
"Home is heaven and orgies are vile,
But you *need* an orgy, once in a while."
Ogden Nash (1902-1971)

On 23/09/2021 13:27, Java Jive wrote:
> On 23/09/2021 10:57, Bob Latham wrote:
>>
>> Why do I know this, I've not touched one this century and yet I can't
>> remember what I had to tea last night.:-)
>
> That's just the way old people's memories work, and it poses an
> interesting evolutionary question. Why should old people have evolved
> to remember best what happened in their distant childhood and youth?
>
> Well, I suspect it works like this: Consider some obscure tribe living
> by subsistence, there's a bad drought, and you're an old member of the
> tribe, almost the last surviving member of your generation, who because
> of your old age is dependent on younger people for your subsistence.
> There would be zilch evolutionary advantage in their keeping you alive
> if all you could remember was what happened yesterday, because everyone
> else can remember that too, and probably better, but if you can remember
> that during a similar drought in your childhood your grandfather led
> them to a distant watering hole several days' walk to the north west,
> and thereby saved them, that is much more useful information to the
> survival of all, and thereby of you.
>

I read something ages ago on similar lines to yours but expressed in
practical terms. In primitive times, there was no birth control, and the
male spent most of hos time hunting for food, while the female prepared
what was caught, fetched water, cooked, made clothes etc when not
feeding and tending to babies. Meanwhile the grandparents were too old
for physically demanding things but had the time and the patience to
teach their grandchildren the life skills they would need when they grow
up, and the traditions that they would carry forward.

That gave the elderly a day to day role rather than just being useful
for their memories. (Also bear in mind that "elderly" in those times is
what we would regard as middle-aged now. Life expectancy was a lot shorter.)

Jim

On 23/09/2021 20:31, Indy Jess John wrote:
> On 23/09/2021 13:27, Java Jive wrote:
>> On 23/09/2021 10:57, Bob Latham wrote:
>>>
>>> Why do I know this, I've not touched one this century and yet I can't
>>> remember what I had to tea last night.:-)
>>
>> That's just the way old people's memories work, and it poses an
>> interesting evolutionary question.  Why should old people have evolved
>> to remember best what happened in their distant childhood and youth?
>>
>> Well, I suspect it works like this:  Consider some obscure tribe living
>> by subsistence, there's a bad drought, and you're an old member of the
>> tribe, almost the last surviving member of your generation, who because
>> of your old age is dependent on younger people for your subsistence.
>> There would be zilch evolutionary advantage in their keeping you alive
>> if all you could remember was what happened yesterday, because everyone
>> else can remember that too, and probably better, but if you can remember
>> that during a similar drought in your childhood your grandfather led
>> them to a distant watering hole several days' walk to the north west,
>> and thereby saved them, that is much more useful information to the
>> survival of all, and thereby of you.
>
> I read something ages ago on similar lines to yours but expressed in
> practical terms. In primitive times, there was no birth control, and the
> male spent most of hos time hunting for food, while the female prepared
> what was caught, fetched water, cooked, made clothes etc when not
> feeding and tending to babies. Meanwhile the grandparents were too old
> for physically demanding things but had the time and the patience to
> teach their grandchildren the life skills they would need when they grow
> up, and the traditions that they would carry forward.
>
> That gave the elderly a day to day role rather than just being useful
> for their memories. (Also bear in mind that "elderly" in those times is
> what we would regard as middle-aged now. Life expectancy was a lot
> shorter.)

Yes, the grandmother effect, whereby sexual reproductivity dies in the
aged, but they survive because they still have a useful role to play,
and by fulfilling that role they help their own offspring reproduce more
successfully that they would be able to do. IIRC it is known to happen
in only three species, ourselves, killer whales, and one other which
I've forgotten. In killer whales, orca, the matriarchs stop breeding,
but still continue to lead the pods and catch food for their male
offspring, thus enabling them to reproduce more successfully.

As far as memory goes, ISTR hearing anecdotal evidence that where
poaching is a problem, the most likely elephants in a herd to get
poached are the matriarchs, because they have bigger tusks, and when the
senior matriarch is killed, the remaining herd sometimes make less wise
decisions.

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

On Thu, 23 Sep 2021 13:10:43 +0100, Java Jive <java@evij.com.invalid>
wrote in <sihqs5$1aqj$1@gioia.aioe.org>:

>On 22/09/2021 10:15, Jim Lesurf wrote:
>>
>> In article <596f71819bcharles@candehope.me.uk>, charles
>> <charles@candehope.me.uk> wrote:
>>
>>> I saw the letter that Sinclair wrote to the BBC on this subject. He said
>>> the BBC spcoification for the BBC Micro, and in particular BBC Basic,
>>> was totally wrong. He would, however, allow the BBC to put their name on
>>> one of his machines. I, also, knew the chap who got paid a significant
>>> sum by Sinclair to make BBC Baisic fit his ZX81 (I think) laptop.
>>
>> Uncle Clive had some excellent ideas, but suffered from a tendency to
>> impliment them poorly. e.g. his liking for 'cheap' components to save
>> money... leading to product unreliability or bothersome behaviour.[1]
>
>Yes, very much so. I remember buying one of the first pocket
>calculators, a Sinclair, which after a short while became useless
>because its on/off switch was unreliable. It would turn off while you
>were doing a calculation. Some while later I bought one of the first
>programmable calculators, again a Sinclair: "Wonderful!", I thought, "I
>can program it once, and then just key in the results of a physics
>experiment one by one and read off the result to enter into the table
>and plot on the graph!" Useless, same problem!

I was at the Compec exhibition in London in November 1980 and I remember
a bunch of techies from various companies going out for dinner the
evening before the exhibition opened. Among the various things being
passed around was (IIRC) a manual for a Sinclair ZX81 which was being
developed at the time. The manual included a picture of the keyboard and
it was generally agreed that they had got the feel of the keyboard just
right in the manual.

I was there with some people from Acorn because my then boss was a mate
of Hermann's and a colleague and I had been lent to Acorn to do the
software for the first version of Econet. We got it working just in time
for the exhibition running on a System-3 and several Atoms.

As far as I remember from those days, one of the things that made the
Acorn product the winner was that it was more robust than the Sinclair
offering. The teletext mode which used very little screen memory and the
user port also made it a very versatile machine. I know that it ended up
being used as an industrial controller among other things.

Java Jive <java@evij.com.invalid> wrote:
> On 23/09/2021 14:20, Jeff Gaines wrote:
>> On 23/09/2021 in message <sihrrh$1q3h$1@gioia.aioe.org> Java Jive wrote:
>>
>>> but if you can remember that during a similar drought in your
>>> childhood your grandfather led them to a distant watering hole several
>>> days' walk to the north west, and thereby saved them, that is much
>>> more useful information to the survival of all, and thereby of you.
>>
>> But once you've told everybody else where the water is they can do you
>> in and save water and food :-)
>
> But who knows what else you might be able to remember that
> might be useful?

I've recently been reading some sagas from the Caucasus,
and one of them made exactly this general point: at the
start, the Nata would kill their old people, but one
couldn't do the proper thing and kill his aged father,
so hid him in a cave and secretly kept him fed. Along
came a terrible famine, father provides suspiciously useful
advice to son, secret discovered, tribe saved, change of
cultural practice.

#Paul

On 23/09/2021 23:45, Owen Rees wrote:
> I know that it ended up
> being used as an industrial controller among other things.

Some were being used for that many years after most people had forgotten
about the BBC computer series.

In article <sifn29$12ob$1@gioia.aioe.org>, Max Demian
<max_demian@bigfoot.com> wrote:
> The main shortcoming of the BBC Micro was that they thought everyone
> would buy the "second processor" and just use the BBC Micro as an
> input/output device; hence the profligate use of 6502 address space and
> RAM on the Model B. (32kB of ROM leaving only 32kB for RAM, and some of
> the display modes use 20k of RAM, and a lot is "reserved".)

To a large extent Acorn saw the initial A and B models as 'get yer going'.
The Master series was a useful improvement.

That said, the B did what it was meant to do for the BBC, etc. We had one
running an interferometer for decades, and used them to write documents, di
analysis, etc. I believe a few people even played 'Elite' on it as well...
8-]

I certainly found it far more useful than an ICL1700! You got 100% of its
time, and no cards, paper tape, etc, etc.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
biog http://jcgl.orpheusweb.co.uk/history/ups_and_downs.html
Audio Misc http://www.audiomisc.co.uk/index.html

On 23/09/2021 in message <5970660bbcnoise@audiomisc.co.uk> Jim Lesurf wrote:

>That said, the B did what it was meant to do for the BBC, etc. We had one
>running an interferometer for decades, and used them to write documents, di
>analysis, etc. I believe a few people even played 'Elite' on it as well...
>8-]

Brother in Law and I hacked a pirate copy of Elite to run but found it
boring to play.

--
Jeff Gaines Wiltshire UK
There are 3 types of people in this world. Those who can count, and those
who can't.

On Wed, 22 Sep 2021 10:15:05 +0100, Jim Lesurf <noise@audiomisc.co.uk>
wrote:

>Uncle Clive had some excellent ideas, but suffered from a tendency to
>impliment them poorly. e.g. his liking for 'cheap' components to save
>money... leading to product unreliability or bothersome behaviour.

Yes, this certainly applied to the little radio and hi-fi kits that
were popular in the 1960s. Sometimes school friends would build these
(because they were cheap) but be unable to get them to work, and then
bring them to one of the small group of us who were known to be into
electronics to ask for help. I could usually fix them, but the only
kits that I couldn't get to do anything were some of the Sinclair
ones. I particularly remember a very simple FM radio and a "class D"
hi-fi amplifier for example. I regarded Sinclair electronics as junk.

On the other hand, if the ZX81 computer kit hadn't been such a
cheapskate shoddy design, many of us who derived inspiration from it,
leading to careers in computing in some cases, wouldn't have been able
to afford it at all. It was a clever marketing strategy to miss out
the most expensive bits - the screen and storage device - on the
grounds that most people would have these things already, and to
simplify as far as possible the next most expensive bit - the keyboard
- but it had the result that the device effectively became a "proof of
concept" that inspired many to explore the subject further using
better electronics that usually worked.

Rod.

On Thu, 23 Sep 2021 23:11:31 +0100, Java Jive <java@evij.com.invalid>
wrote:

>Yes, the grandmother effect, whereby sexual reproductivity dies in the
>aged, but they survive because they still have a useful role to play,
>and by fulfilling that role they help their own offspring reproduce more
>successfully that they would be able to do. IIRC it is known to happen
>in only three species, ourselves, killer whales, and one other which
>I've forgotten.

Elephants maybe? I'm surprised it's only three species, as there are
quite a lot that have some sort of social lifestyle, and I would have
thought that experienced oldies would be useful in most of them.

Rod.

On Fri, 24 Sep 2021 11:15:39 +0100
Roderick Stewart <rjfs@escapetime.myzen.co.uk> wrote:

> On the other hand, if the ZX81 computer kit hadn't been such a
> cheapskate shoddy design, many of us who derived inspiration from it,
> leading to careers in computing in some cases, wouldn't have been able
> to afford it at all. It was a clever marketing strategy to miss out
> the most expensive bits - the screen and storage device - on the
> grounds that most people would have these things already, and to
> simplify as far as possible the next most expensive bit - the keyboard
> - but it had the result that the device effectively became a "proof of
> concept" that inspired many to explore the subject further using
> better electronics that usually worked.
>
> Rod.

Precisely what happened to me. My next PC was a Heathkit, that could go
up to a massive 720 Kb of RAM, a tad more than the IBM personal
computer of the day, which topped out at 640. The tape program storage
was the weakest point of the ZX81 in my personal experience.
I still have my ZX81, purchased in the US, but it hasn't been fired up
for several decades now.
--
Davey.

On 24/09/2021 14:35, Davey wrote:
> On Fri, 24 Sep 2021 11:15:39 +0100
> Roderick Stewart <rjfs@escapetime.myzen.co.uk> wrote:
>
>> On the other hand, if the ZX81 computer kit hadn't been such a
>> cheapskate shoddy design, many of us who derived inspiration from it,
>> leading to careers in computing in some cases, wouldn't have been able
>> to afford it at all. It was a clever marketing strategy to miss out
>> the most expensive bits - the screen and storage device - on the
>> grounds that most people would have these things already, and to
>> simplify as far as possible the next most expensive bit - the keyboard
>> - but it had the result that the device effectively became a "proof of
>> concept" that inspired many to explore the subject further using
>> better electronics that usually worked.
>>
>> Rod.
>
> Precisely what happened to me. My next PC was a Heathkit, that could go
> up to a massive 720 Kb of RAM, a tad more than the IBM personal
> computer of the day, which topped out at 640. The tape program storage
> was the weakest point of the ZX81 in my personal experience.
> I still have my ZX81, purchased in the US, but it hasn't been fired up
> for several decades now.
>

ZX81? That has CVBS output if my memory serves me right?

Is there a ny modern tv sets still made that can accept a CVBS input?

On 24/09/2021 14:50, SH wrote:
> On 24/09/2021 14:35, Davey wrote:
>> On Fri, 24 Sep 2021 11:15:39 +0100
>> Roderick Stewart <rjfs@escapetime.myzen.co.uk> wrote:
>>
>>> On the other hand, if the ZX81 computer kit hadn't been such a
>>> cheapskate shoddy design, many of us who derived inspiration from it,
>>> leading to careers in computing in some cases, wouldn't have been able
>>> to afford it at all. It was a clever marketing strategy to miss out
>>> the most expensive bits - the screen and storage device - on the
>>> grounds that most people would have these things already, and to
>>> simplify as far as possible the next most expensive bit - the keyboard
>>> - but it had the result that the device effectively became a "proof of
>>> concept" that inspired many to explore the subject further using
>>> better electronics that usually worked.

>> Precisely what happened to me. My next PC was a Heathkit, that could go
>> up to a massive 720 Kb of RAM, a tad more than the IBM personal
>> computer of the day, which topped out at 640. The tape program storage
>> was the weakest point of the ZX81 in my personal experience.
>> I still have my ZX81, purchased in the US, but it hasn't been fired up
>> for several decades now.

> ZX81? That has CVBS output if my memory serves me right?
>
> Is there a ny modern tv sets still made that can accept a CVBS input?

Surely the ZX81 produced a UHF signal on a particular channel. I don't
think any TVs would accept a composite signal before SCARTs.

--
Max Demian

In article <NuidnbvNx5sPn9P8nZ2dnUU78cHNnZ2d@brightview.co.uk>,
Max Demian <max_demian@bigfoot.com> wrote:
> On 24/09/2021 14:50, SH wrote:
> > On 24/09/2021 14:35, Davey wrote:
> >> On Fri, 24 Sep 2021 11:15:39 +0100
> >> Roderick Stewart <rjfs@escapetime.myzen.co.uk> wrote:
> >>
> >>> On the other hand, if the ZX81 computer kit hadn't been such a
> >>> cheapskate shoddy design, many of us who derived inspiration from it,
> >>> leading to careers in computing in some cases, wouldn't have been able
> >>> to afford it at all. It was a clever marketing strategy to miss out
> >>> the most expensive bits - the screen and storage device - on the
> >>> grounds that most people would have these things already, and to
> >>> simplify as far as possible the next most expensive bit - the keyboard
> >>> - but it had the result that the device effectively became a "proof of
> >>> concept" that inspired many to explore the subject further using
> >>> better electronics that usually worked.

> >> Precisely what happened to me. My next PC was a Heathkit, that could go
> >> up to a massive 720 Kb of RAM, a tad more than the IBM personal
> >> computer of the day, which topped out at 640. The tape program storage
> >> was the weakest point of the ZX81 in my personal experience.
> >> I still have my ZX81, purchased in the US, but it hasn't been fired up
> >> for several decades now.

> > ZX81? That has CVBS output if my memory serves me right?
> >
> > Is there a ny modern tv sets still made that can accept a CVBS input?

> Surely the ZX81 produced a UHF signal on a particular channel. I don't
> think any TVs would accept a composite signal before SCARTs.

off the shelf one, probably true, but I added a video input pcb to my Thorn
14" set. It made the BBC Micro 80 column text usable.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On Fri, 24 Sep 2021 18:22:13 +0100
charles <charles@candehope.me.uk> wrote:

> In article <NuidnbvNx5sPn9P8nZ2dnUU78cHNnZ2d@brightview.co.uk>,
> Max Demian <max_demian@bigfoot.com> wrote:
> > On 24/09/2021 14:50, SH wrote:
> > > On 24/09/2021 14:35, Davey wrote:
> > >> On Fri, 24 Sep 2021 11:15:39 +0100
> > >> Roderick Stewart <rjfs@escapetime.myzen.co.uk> wrote:
> > >>
> > >>> On the other hand, if the ZX81 computer kit hadn't been such a
> > >>> cheapskate shoddy design, many of us who derived inspiration
> > >>> from it, leading to careers in computing in some cases,
> > >>> wouldn't have been able to afford it at all. It was a clever
> > >>> marketing strategy to miss out the most expensive bits - the
> > >>> screen and storage device - on the grounds that most people
> > >>> would have these things already, and to simplify as far as
> > >>> possible the next most expensive bit - the keyboard
> > >>> - but it had the result that the device effectively became a
> > >>> "proof of concept" that inspired many to explore the subject
> > >>> further using better electronics that usually worked.
>
> > >> Precisely what happened to me. My next PC was a Heathkit, that
> > >> could go up to a massive 720 Kb of RAM, a tad more than the IBM
> > >> personal computer of the day, which topped out at 640. The tape
> > >> program storage was the weakest point of the ZX81 in my personal
> > >> experience. I still have my ZX81, purchased in the US, but it
> > >> hasn't been fired up for several decades now.
>
> > > ZX81? That has CVBS output if my memory serves me right?
> > >
> > > Is there a ny modern tv sets still made that can accept a CVBS
> > > input?
>
> > Surely the ZX81 produced a UHF signal on a particular channel. I
> > don't think any TVs would accept a composite signal before SCARTs.
>
> off the shelf one, probably true, but I added a video input pcb to my
> Thorn 14" set. It made the BBC Micro 80 column text usable.
>

Yes, my USA ZX81 had as standard a US CH.3 output, I think, and I took
an output from somewhere in it and injected that into the video section
of a cheap B&W TV set. Much clearer than the Ch.3 rendition.
--
Davey.

On Fri, 24 Sep 2021 17:53:29 +0100, Max Demian <max_demian@bigfoot.com> wrote:

> Surely the ZX81 produced a UHF signal on a particular channel. I don't
> think any TVs would accept a composite signal before SCARTs.

Not true. We had a JVC 7115GB 14" portable that had a BNC input (& output)
for use with the BBC micro around 1981 or so.
I've still got the manual for it, even though the TV itself is long
gone (I know...).

In message <slrnsks7ii.45ng.abuse@news.pr.network>, Paul Ratcliffe
<abuse@orac12.clara34.co56.uk78> writes
>On Fri, 24 Sep 2021 17:53:29 +0100, Max Demian <max_demian@bigfoot.com> wrote:
>
>> Surely the ZX81 produced a UHF signal on a particular channel. I don't
>> think any TVs would accept a composite signal before SCARTs.
>
>Not true. We had a JVC 7115GB 14" portable that had a BNC input (& output)
>for use with the BBC micro around 1981 or so.
>I've still got the manual for it, even though the TV itself is long
>gone (I know...).

At work, in the mid-1970s, we had a 13 inch Sony that had a BNC video
input (and probably sound - and maybe also outputs). However, it might
not have been the normal domestic set, but instead was possibly a
professional/industrial version.
--
Ian

On 24/09/2021 20:36, Ian Jackson wrote:
> In message<slrnsks7ii.45ng.abuse@news.pr.network>, Paul Ratcliffe
> <abuse@orac12.clara34.co56.uk78> writes
>> On Fri, 24 Sep 2021 17:53:29 +0100, Max Demian<max_demian@bigfoot.com> wrote:
>>
>>> Surely the ZX81 produced a UHF signal on a particular channel. I don't
>>> think any TVs would accept a composite signal before SCARTs.
>>
>> Not true. We had a JVC 7115GB 14" portable that had a BNC input (& output)
>> for use with the BBC micro around 1981 or so.
>> I've still got the manual for it, even though the TV itself is long
>> gone (I know...).
>
> At work, in the mid-1970s, we had a 13 inch Sony that had a BNC video
> input (and probably sound - and maybe also outputs). However, it might
> not have been the normal domestic set, but instead was possibly a
> professional/industrial version.

Some CCTV controllers have BNC Video input for camera connections, and
it is possible to see that input on a computer monitor plugged into the
CCTV box. It could be worth trying whether the BBC micro output can be
viewed on such a monitor.

Jim

On Fri, 24 Sep 2021 20:55:30 +0100, Indy Jess John
<bathwatchdog@OMITTHISgooglemail.com> wrote:

> Some CCTV controllers have BNC Video input for camera connections, and
> it is possible to see that input on a computer monitor plugged into the
> CCTV box. It could be worth trying whether the BBC micro output can be
> viewed on such a monitor.

Liberties were taken with the standard-ness of the output i.e. it wasn't
very standard, either in timings or levels.
You had to do a (published) mod. to the circuit board to enable the colour
as well. I forget now if you had to add/remove a link or a capacitor.
I know I've got the circuit diagram somewhere as well, but can't remember
where.

On Fri, 24 Sep 2021 14:50:26 +0100, SH <i.love.spam@spam.com> wrote:

>ZX81? That has CVBS output if my memory serves me right?
>
>Is there a ny modern tv sets still made that can accept a CVBS input?

More like "CVS". The "B" was missing.

The ZX81 video signal was 1V for the white background, 0.3V for the
text, and 0V for syncs. At the beginnings and ends of lines, for
simplicity the signal went directly between white level and sync
level. Cheap monochrome TVs with sync-tip restorer circuitry didn't
mind this, but colour sets that expected a back porch to clamp the
signal at black level would clamp on peak white instead.

There was no interlace. Fields were identical, with 310 lines each.

Rod.

In article <agvpkghodhhop4eovkspa5jau1hp9c8dll@4ax.com>, Owen Rees
<orees@hotmail.com> wrote:

> As far as I remember from those days, one of the things that made the
> Acorn product the winner was that it was more robust than the Sinclair
> offering. The teletext mode which used very little screen memory and the
> user port also made it a very versatile machine. I know that it ended up
> being used as an industrial controller among other things.

The BBC B and its 'children' were used to control and data log/process
pretty much all the instruments my group and I developed over the decades.

After I retired, someone drove down from Aberdeen to take my remaining
RiscPCs because the board were what he built into the expensive undersea
remote 'robots' he sold the Oil biz to use for subsurface work under the
North Sea!

The combination of a good I/O interface and the programability and 'single
tasking' mode were a winner for instrumentation work.

And out of the death of Acorn, ARM emerged...

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
biog http://jcgl.orpheusweb.co.uk/history/ups_and_downs.html
Audio Misc http://www.audiomisc.co.uk/index.html