Monitor RS232 comms with millisecond resolution

On 24/06/2010 10:11, Jon Kirwan wrote:
> On Thu, 24 Jun 2010 08:57:40 +0200, David Brown
> <david@westcontrol.removethisbit.com>  wrote:
>
>> On 23/06/2010 23:50, Jon Kirwan wrote:
>>> On Wed, 23 Jun 2010 21:04:55 +0000 (UTC), Grant Edwards
>>> <invalid@invalid.invalid>   wrote:
>>>
>>>> On 2010-06-23, Jon Kirwan<jonk@infinitefactors.org>   wrote:
>>>>> On Wed, 23 Jun 2010 14:13:14 +0200, "Meindert Sprang"
>>>>> <ms@NOJUNKcustomORSPAMware.nl>   wrote:
>>>>>
>>>>>> "Paul Keinanen"<keinanen@sci.fi>   wrote in message
>>>>>> news:9pe3269vevlnos3fn3j1ne6dv7tnfgm293@4ax.com...
>>>>>>> At 62.5 kbit/s the bit time is 16 us, thus +/-8 us error from the
>>>>>>> nominal sampling point from the middle of the bit period would be
>>>>>>> allowed.
>>>>>>
>>>>>> Funny, all the discussions about baudrates and errors. I'd use an ISA COM
>>>>>> card and simply replace the crystal... done it, works like a charm. Only 5
>>>>>> minutes work.
>>>>>
>>>>> Hehe.  But this means you actually _have_ something with an
>>>>> ISA bus on it!!  These days... well.
>>>>
>>>> Then use a PCI card.
>>>>
>>>>> On your point, yes.  A crystal change on any of the usual
>>>>> spate of old ISA boards would easily solve the problem.
>>>>> Forgotten lore.
>>>>
>>>> It works for PCI cards as well.
>>>
>>> I like ISA and simpler software.
>>>
>>> Although I understand reflection wave principles, clock line
>>> skew and serpentine clock lines, and the like, I very much
>>> appreciate being able to use simple logic, wire-wrapping
>>> techniques, and custom circuit design with the ISA bus.  It
>>> is a low-tech bus that can be reached by hobbyists.  PCI, and
>>> not merely because of the hardware but also because of other
>>> aspects (plug and play), out of reach of most hobbyist tools
>>> and skills.
>>>
>>
>> ISA has also always been out of the reach of the hobbyist.
>
> Are you just in a contrary mood, today?  No other explanation
> is possible.
>
> Out of reach???  Hardly.  But I suppose it depends upon what
> is, is.  :)
>
>> While there
>> is no doubt that it is simpler to design an ISA card than a PCI card, in
>> the days of ISA it was hard to make such a card.
>
> IBM, itself (and I know this because I still have them here),
> sold very cheap proto boards for the ISA bus as far back as I
> can recall.  Very beautiful boards, too.  I believe I paid
> close to $30 for each.  1984/1985.
>
>> Information about the
>> bus wasn't as easily available (no Google),
>
> Hogwash.
>
> I still have my technical reference multi-volume binder set
> from IBM with __complete__ documentation.  Very complete.
> Complete BIOS listings, with comments, included, and
> schematics as well.  I used these routinely for hobby
> playing.
>

I suppose it all depends on what you define as "hobbyist".

Finding a source for the documentation, and buying it (assuming these 
manuals were priced similarly to a lot of other comparable technical 
information) would take a lot of effort and money.

It may also be as simple as you being lucky in finding these prototype 
boards from IBM.  Imagine a hobbyist who hadn't found out about these 
and wanted to make an ISA card.

>
>> But the biggest
>> hurdle for a hobbyist would be testing - you need an expendable spare
>> computer to test your card, because of the high risk of frying the whole
>> machine.  These days you can get a cheap PCI bus computer for very
>> little, and second-hand ones for practically nothing.  When ISA was the
>> main bus, a spare computer was a big investment.
>
> Since I do NOT consider myself to be anything other than a
> hobbyist in electronics -- barely that -- and since I already
> know just how darned easy this was for me when I knew far,
> far less than I do now about it, I don't know at all where
> you are coming from.  Or, at least, I simply didn't find all
> the struggles you suggest.
>

You are /far/ beyond what I would consider a hobbyist - you have a lot 
more knowledge and experience, and put a lot more time and money into 
your electronics, than I would classify as hobbyist.  Amateur, perhaps 
(if you don't get paid for it), but I don't expect you would have 
difficulty getting a job as an electronics engineer.


I am not saying that making an ISA board was too hard to do - merely 
that the investment required was at the level of "small professional" 
rather than "hobbyist".


> And by comparison with PCI???  No discussion.
>

All the information about PCI that you could want is a few google 
searches away, as are plenty of example designs to get you started.  And 
you can buy an Altera Max II PCI evaluation board within a hobby budget 
($150), including software drivers.  So playing around with PCI is 
certainly practical for hobbyists - though I agree that making your own 
PCI board is well out of reach, even for a small professional company.

> I used tools developed for PCI at Intel.  I know how much
> they paid for them.  And I know what including PCI on the
> Pentium did to "mom and pop" motherboard manufacturers, too.
> (Intel staff told me this was an internal goal, in fact.)
>
> I won't even debate it.  Not worth the trouble.
>
> Jon

On Thu, 24 Jun 2010 11:07:50 +0200, David Brown
<david@westcontrol.removethisbit.com> wrote:

><snip>
>Finding a source for the documentation, and buying it (assuming these 
>manuals were priced similarly to a lot of other comparable technical 
>information) would take a lot of effort and money.

It wasn't hard.  I'm not certain anymore, but I believe I
first heard about the information either in a magazine or
through the materials received when purchasing.  I do
remember getting a price and part number to order from IBM,
by phone, and then simply writing a check and mailing it off.
It wasn't a lot of money, either.  Especially considering
that the IBM PC/AT, 6MHz and 20Mb hard drive, was priced at
$5495, memory serving.  If you could find a way to peal that
much out of your wallet, the manuals weren't even on the
radar scope.

My recollection is that the "lot of effort and money"
amounted to about 1 day's effort (which I don't consider 'a
lot') and the money wasn't even noticed.  I didn't have to
think longer than a few seconds, I believe.  And when I
received the material and the continuing supported updates to
it, I only felt lucky that I'd taken the trouble.  Never once
thought about the expense of it.  Must have been very small
compared to the PC/AT cost, which itself was 'painful' enough
to me.  I am almost certain I might have not bothered, had
the manual cost more than a couple hundred bucks.  But I'm
not sure, anymore.  Just my 'sense' from memory.

>It may also be as simple as you being lucky in finding these prototype 
>boards from IBM.  Imagine a hobbyist who hadn't found out about these 
>and wanted to make an ISA card.

When I wanted prototyping boards, the ONLY supplier ANYWHERE
in the world that I could find was IBM.  And I darned well
knew I couldn't pony up the cost to hire a board house back
then.  Not then.  They were WAY too expensive and my
knowledge was near zero about ordering such a beast, anyway.
I looked for alternatives, at the time, thinking that IBM had
to be 'expensive' and that I might find less expensive
alternatives.  None existed that I could find.  No one else
had done it, yet.  That came later.

And when they eventually did finally arrive (from Jameco?),
they were obvious garbage.  So I never looked back.  There
was no comparison.

I wasn't lucky, except for the fact that I was lucky that IBM
cared enough to actually create something like this and sell
it.  There just wasn't anyone else around, so no choice and
no luck.  Anyone else actually looking and bothering to call
IBM would have discovered the same thing I did, I think. They
didn't hide the fact.  They just didn't push it with
advertising.  You had to ask, that's all.

Anyone sensible should have been that diligent.  I don't
count myself special that way.

><snip>
>You are /far/ beyond what I would consider a hobbyist - you have a lot 
>more knowledge and experience, and put a lot more time and money into 
>your electronics, than I would classify as hobbyist.  Amateur, perhaps 
>(if you don't get paid for it), but I don't expect you would have 
>difficulty getting a job as an electronics engineer.

I've never hired out a single hour of time as an electronics
engineer and don't believe I'd be competent enough to do so,
either.  Comprehensiveness is what is required for
professional services and I can't deliver that.  I know some
things, but am terribly spotty elsewhere.

I started out as a hobbyist and that's what I imagine I am.
'Amateur' would work about as well as a word for it, though
I'm not sure there is a difference that amounts to anything.

>I am not saying that making an ISA board was too hard to do - merely 
>that the investment required was at the level of "small professional" 
>rather than "hobbyist".

I'm a hobbyist.  Honest.

>> And by comparison with PCI???  No discussion.
>
>All the information about PCI that you could want is a few google 
>searches away, as are plenty of example designs to get you started.  And 
>you can buy an Altera Max II PCI evaluation board within a hobby budget 
>($150), including software drivers.  So playing around with PCI is 
>certainly practical for hobbyists - though I agree that making your own 
>PCI board is well out of reach, even for a small professional company.

This 'inaccessability' for even small professional companies
is the center of my point.  ISA is not only accessible to
smaller professionals, but to hobbyists too.  And wire-wrap
_and_ sockets work nicely!!

Jon

David Brown wrote:

> I suppose it all depends on what you define as "hobbyist".
> 
> Finding a source for the documentation, and buying it (assuming these
> manuals were priced similarly to a lot of other comparable technical
> information) would take a lot of effort and money.
> 
> It may also be as simple as you being lucky in finding these prototype
> boards from IBM.  Imagine a hobbyist who hadn't found out about these
> and wanted to make an ISA card.

Active (must have been them, can't imagine where else I'd have got them 
then) sold boards with the appropriate edge connector and traces for typical 
interface chips -- then a huge wire-wrap area.

Personal Computer Technical Reference had full schematics for the PC side of 
the interface.  Mine was off the shelf from a bookstore in Boston.  
Admitted, the farther from MIT, the harder they were to find.  They were 
more scarce in Toronto.

And my first MIDI adaptor was a kit from a technically-aware hole in the 
wall called Computer Parts Galore.

	Mel.

On 24/06/2010 13:11, Jon Kirwan wrote:
> On Thu, 24 Jun 2010 11:07:50 +0200, David Brown
> <david@westcontrol.removethisbit.com>  wrote:
>
>> <snip>
>> Finding a source for the documentation, and buying it (assuming these
>> manuals were priced similarly to a lot of other comparable technical
>> information) would take a lot of effort and money.
>
> It wasn't hard.  I'm not certain anymore, but I believe I
> first heard about the information either in a magazine or
> through the materials received when purchasing.  I do
> remember getting a price and part number to order from IBM,
> by phone, and then simply writing a check and mailing it off.
> It wasn't a lot of money, either.  Especially considering
> that the IBM PC/AT, 6MHz and 20Mb hard drive, was priced at
> $5495, memory serving.  If you could find a way to peal that
> much out of your wallet, the manuals weren't even on the
> radar scope.
>

I guess it is this more than anything else that puts ISA out of the 
range of hobbyists to my mind - you don't mess around with putting 
home-made cards into a $5500 computer unless you are happy to risk 
damaging it, or you are /very/ confident of your abilities.  Either way, 
you are not a hobbyist.

Hobbyists who wanted to connect a card to a PC gave them an RS-232 
interface or a parallel port connection - just like these days they give 
them a USB connection or an Ethernet port (or possibly a RS-232 connection).

On 2010-06-23, Jon Kirwan <jonk@infinitefactors.org> wrote:

>>Swapping in a 2.00MHz oscillator for a 1.843MHz oscillator on a PCI
>>card requires _exactly_the_same_ skills as doing it on an ISA card.
>
> Not so.  I'm looking right now at two such cards, one ISA and
> one PCI.  The ISA board has a large, socketed crystal module.
> The PCI a tiny, SMT unit.

That's a characteristic of those two particular boards.  It's not a
characteristic of ISA vs. PCI bus.

> The skills required for modifying one is much different (and the tool
> tips required, too.) It _may_ be the case, but not necessarily so as
> these two boards easily illustrate to me.

Replacing an SMT oscillator is really quite trivial.  It's easier than
replacing the non-socketed, through-hole parts on most ISA boards.

-- 
Grant Edwards               grant.b.edwards        Yow! ... the HIGHWAY is
                                  at               made out of LIME JELLO and
                              gmail.com            my HONDA is a barbequeued
                                                   OYSTER!  Yum!

On Thu, 24 Jun 2010 14:06:05 +0000 (UTC), Grant Edwards
<invalid@invalid.invalid> wrote:

>On 2010-06-23, Jon Kirwan <jonk@infinitefactors.org> wrote:
>
>>>Swapping in a 2.00MHz oscillator for a 1.843MHz oscillator on a PCI
>>>card requires _exactly_the_same_ skills as doing it on an ISA card.
>>
>> Not so.  I'm looking right now at two such cards, one ISA and
>> one PCI.  The ISA board has a large, socketed crystal module.
>> The PCI a tiny, SMT unit.
>
>That's a characteristic of those two particular boards.  It's not a
>characteristic of ISA vs. PCI bus.

Which doesn't injur my point at all.

>> The skills required for modifying one is much different (and the tool
>> tips required, too.) It _may_ be the case, but not necessarily so as
>> these two boards easily illustrate to me.
>
>Replacing an SMT oscillator is really quite trivial.  It's easier than
>replacing the non-socketed, through-hole parts on most ISA boards.

With good tools for SMT available.  I recently _did_ after 30
years finally purchase my very first fine tip for attempting
such work.  But for 30 years, this would have been a disaster
had I tried, while through hole is something I am quite long
since used to handling.

Of course, none of this is about my earlier point regarding
ISA vs PCI for hobbyists.  Itself, of course, nothing about
the earlier thread.  So we are far out to field now.

Jon

On Thu, 24 Jun 2010 15:35:04 +0200, David Brown
<david@westcontrol.removethisbit.com> wrote:

>On 24/06/2010 13:11, Jon Kirwan wrote:
>> On Thu, 24 Jun 2010 11:07:50 +0200, David Brown
>> <david@westcontrol.removethisbit.com>  wrote:
>>
>>> <snip>
>>> Finding a source for the documentation, and buying it (assuming these
>>> manuals were priced similarly to a lot of other comparable technical
>>> information) would take a lot of effort and money.
>>
>> It wasn't hard.  I'm not certain anymore, but I believe I
>> first heard about the information either in a magazine or
>> through the materials received when purchasing.  I do
>> remember getting a price and part number to order from IBM,
>> by phone, and then simply writing a check and mailing it off.
>> It wasn't a lot of money, either.  Especially considering
>> that the IBM PC/AT, 6MHz and 20Mb hard drive, was priced at
>> $5495, memory serving.  If you could find a way to peal that
>> much out of your wallet, the manuals weren't even on the
>> radar scope.
>
>I guess it is this more than anything else that puts ISA out of the 
>range of hobbyists to my mind - you don't mess around with putting 
>home-made cards into a $5500 computer unless you are happy to risk 
>damaging it, or you are /very/ confident of your abilities.  Either way, 
>you are not a hobbyist.

Oh, cripes.  I have nearly destroyed a _new_ $2,000 piece of
equipment back around that time merely because I hadn't
realized that the ground plug on one properly designed piece
of test equipment I was using might cause a hot-side short to
the IBM Model 85 electronic typewriter which didn't have such
a plug and was plugged in reverse-wise.  Nicely destroyed a
power supply board, which I had to repair.

There is no question I was barely a hobbyist, if that, at the
time.  And yes, I was willing to take risks with my money
because I wanted to learn, too.  I did what I knew to do to
avoid throwing money in the dumpster or killing myself, but
I'm quite certain I didn't do as much as those smarter than
me did.  I made plenty of mistakes as I went.  And I have had
zero formal training here, by the way.  Even to this day.

I don't know why you want to imagine I'm something I know I'm
not.  But there it is.

>Hobbyists who wanted to connect a card to a PC gave them an RS-232 
>interface or a parallel port connection - just like these days they give 
>them a USB connection or an Ethernet port (or possibly a RS-232 connection).

I used those, too.  For example, in the above typewriter case
I was scoping out the reed relay signals so that I could
figure out how to turn it into a printer.  I then designed
and programmed by own 8031 board, with EPROM, and rat-nest
wired the thing across the reed relays and brought out a
ribbon cable to the tiny proto box I had.  There, I used 1488
and 1489 level shifters with the 80C31 and a serial port to
the PC for use as a printer.  Worked first time (after fixing
that power supply board in the electronic typewriter that I'd
wrecked.)  But this was almost around the same time when I
also did my first proto board that plugged directly into that
$5500 PC/AT.  And I was barely any smarter at that point and
nearly as likely to destroy something there, too.

You learn by screwing up and then reinforce the stuff you did
learn well, by succeeding.

And I'm still a hobbyist.

Jon

Last time on comp.arch.embedded, Jon Kirwan <jonk@infinitefactors.org>
said:

>>If possible I'd like it to run at a non-standard baud rate (62,500 baud).
>
>I'm not sure an IBM PC uart can run at that rate. 

It could if you're willing to change the crystal on the UART card...

On Thu, 24 Jun 2010 21:27:15 -0700, Fred <fuque@hotmail.com>
wrote:

>Last time on comp.arch.embedded, Jon Kirwan <jonk@infinitefactors.org>
>said:
>
>>>If possible I'd like it to run at a non-standard baud rate (62,500 baud).
>>
>>I'm not sure an IBM PC uart can run at that rate. 
>
>It could if you're willing to change the crystal on the UART card...

Yeah.  I think that has been mentioned in this thread
about... 20 times already?

And have you actually done this on a modern PC?

In any case, I haven't looked recently, but few PCs these
days seem to sport RS-232 or RS-485 ports.  For those that
may, high integration on the board may not make it it so
easy.  I believe the ones old enough to actually have a south
bridge probably use a super I/O chip or have it integrated
into the south bridge along with the APIC and perhaps have
some divider used to get the "pc standard" rates created.  It
all has to look like an ISA dohicky or old software won't
work right.  PCI boards also exist and they have drivers that
are probably Windows-standard, too, but then that is a whole
other thing to worry about and I'm not sure how the WinOldAp
or NTVDM emulates the old chips into the DOS boxes.

It's been a long time since I looked, but unless I heard
directly from someone who has achieved this with a new PC
system, I'd be skeptical of a claim about it being easy to
do.

Maybe someone has and can fill us in about it.

Jon

Last time on comp.arch.embedded, Jon Kirwan <jonk@infinitefactors.org>
said:

>On Thu, 24 Jun 2010 21:27:15 -0700, Fred <fuque@hotmail.com>
>wrote:
>
>>Last time on comp.arch.embedded, Jon Kirwan <jonk@infinitefactors.org>
>>said:
>>
>>>>If possible I'd like it to run at a non-standard baud rate (62,500 baud).
>>>
>>>I'm not sure an IBM PC uart can run at that rate. 
>>
>>It could if you're willing to change the crystal on the UART card...
>
>Yeah.  I think that has been mentioned in this thread
>about... 20 times already?

I only saw one other mention; somehow I missed the other 19.

>And have you actually done this on a modern PC?

Not on a PC motherboard, but I have done it on an expansion card.

>In any case, I haven't looked recently, but few PCs these
>days seem to sport RS-232 or RS-485 ports.

Just the other day I bought a 2-port RS-232 PCI expansion card. Cost
me $17 at a local retail store, but you can get the same card online
for ~$12.

>It's been a long time since I looked, but unless I heard
>directly from someone who has achieved this with a new PC
>system, I'd be skeptical of a claim about it being easy to
>do.
>
>Maybe someone has and can fill us in about it.

The card I just bought has a normal-looking, through-hole-mounted
crystal on it. Even a software guy like me could swap it out.