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'Microchip discontinued programmers???'
1996\12\19@214007 by B. Davies

picon face
In some threads recently I have read about microchip  no longer supporting
certain programmers.   I tried today to order a picstart 16B1 programmer from
Digikey,  they say part # is discontinued and refers to picstart plus, they
then enter that # and it refers to the 16B1.    I am new to this pic thing
and was looking forward to getting started now I am confused.  Is Digikey
getting messed up or is there something more sinister afoot?   Seriously
though I browsed microchips homepage 2 nights ago and down loaded a brochure
for the 16B1.
Does anyone out there know  what is happening?   Or do you know who I can
contact?

Thanks   Brian

1996\12\19@223031 by Jim Ham

picon face
At 09:39 PM 12/19/96 -0500, you wrote:
>In some threads recently I have read about microchip  no longer supporting
>certain programmers.   I tried today to order a picstart 16B1 programmer from
>Digikey,  they say part # is discontinued and refers to picstart plus, they
>then enter that # and it refers to the 16B1.    I am new to this pic thing
>and was looking forward to getting started now I am confused.  Is Digikey
>getting messed up or is there something more sinister afoot?   Seriously
>though I browsed microchips homepage 2 nights ago and down loaded a brochure
>for the 16B1.
>Does anyone out there know  what is happening?   Or do you know who I can
>contact?
>
>Thanks   Brian
>
>
I just purchased a PicStart Plus from Digikey - I got it in the mail today.
I haven't turned it on yet, so no comments except that it is available.

Jim
Jim Ham, Porcine Associates
(415)326-2669 fax(415)326-1071
http://www.porcine.com

1996\12\19@224739 by Brooke

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face
Jim Ham wrote:
>
.......
> I just purchased a PicStart Plus from Digikey - I got it in the mail today.
> I haven't turned it on yet, so no comments except that it is available.

Jim:

Check the firmware revision from the MPLAB enable window (1.20.00 now).
You should have also received a blank windowed 17C44 to allow
upgrading the firmware. If not contact the factory.
Keep the old OTP 17C44 to allow reusing the window part.
My PSP works great.

Brooke

1996\12\19@231329 by Lynn Richardson

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face
Microchip is pushing the Plus now as a replacement for both the 16B1 and
the 16C as it's supposed to support all the different PIC flavors.  Of
course you have to replace or reprogram the 17C44 in the programming
adapter every time they come out with a new chip! :-{

Also you have to use MPLAB to talk to the adapter, and that requires
Windows.  It has problems with Windows 95, causes sporadic errors that can
require you to kill off MPLAB or hard reboot your PC. I use a Dell 166MHz
Pentium with 48Meg of ram, a 2.1Gig HD on a LAN.  Some other programs I
use also have problems with W95, so if you stick with W 3.1 you should be
ok.

I find MPLAB to be a little clumsy to use, but I'm an old phart who's been
messing around with microcontrollers since 1977 and have used a wide
variety of assemblers, editors and programming adapters and gotten set in
my ways.  I like to use my favorite editor to write code and use the
manufacturer's cross assembler (if available) to get hex code and a simple
programming adaptor to dump my program into the target chip.

You'll have to use Microchip's MPASM (or its Windows variation) to
assemble your code on either adaptor, but it works quite well so no
worries.  MPLAB will automatically use the windows version.

The 16B1 uses MPSIM to simulate your program and has some nice features
like settable trace address ranges, break points on program location
and/or variable (register) values or changes.  On my 166MHz Pentium the
simulator takes from 1000 to 10000 times longer to execute my code than
the actual chip would but thats normal.  VGA adapter speed seems to be the
critical parameter.  You can speed things up by tracing only those things
you need to watch, the fewer, the faster.  I haven't tried MPLAB's
simulator, so no comment.

The Plus programming adapter is a better design than the 16B1.  It has a
nicely designed plastic case instead of an unprotected PCB like the 16B1.

Final comments: If you're new to programming MCUs and don't plan on
programming any other chip brands, the Plus and MPLAB IDE is a fair start,
but a little dear at $200.  Forget the 16B1, it's history unless you can
find a used one or someones old inventory.  I'm very interested in Jim
Robertson's products, what I've seen on his web pages and the beta Phoenix
driver for the 16B look very good.  His hardware and software is available
from ITU (don't recall the web address) in the States.

73
_____________________________________________
Lynn Richardson           | spam_OUTlrichTakeThisOuTspamqni.com    \
Progress Instrument, Inc. | wa0znl.ampr.org  |
807 NW Commerce Drive     |  [44.46.176.3]   |
Lee's Summit, MO 64086    |                  |
(816)524-4442 F:246-4556  |                  /
---------------------------------------------

On Thu, 19 Dec 1996, B. Davies wrote:

{Quote hidden}

1996\12\20@020724 by fastfwd
face
flavicon
face
Lynn Richardson <.....PICLISTKILLspamspam@spam@MITVMA.MIT.EDU> wrote:

> Microchip is pushing the Plus now as a replacement for both the 16B1
> and the 16C as it's supposed to support all the different PIC
> flavors.  Of course you have to replace or reprogram the 17C44 in
> the programming adapter every time they come out with a new chip!

Lynn:

I can't tell if you were serious or not, but that last sentence is
not true.

While the early Picstart Plus programmers DID require a firmware
upgrade shortly after they were shipped, it is not Microchip's
intent to require any further upgrades; the existing firmware should
work for all PICs in the foreseeable future.

-Andy

=== Andrew Warren - fastfwdspamKILLspamix.netcom.com                 ===
=== Fast Forward Engineering - Vista, California          ===
===                                                       ===
=== Did the information in this post help you?  Consider  ===
=== contributing to the PICLIST Fund.  Details are at:    ===
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1996\12\20@020729 by fastfwd

face
flavicon
face
B. Davies <.....PICLISTKILLspamspam.....MITVMA.MIT.EDU> wrote:

> In some threads recently I have read about microchip  no longer
> supporting certain programmers.   I tried today to order a
> picstart 16B1 programmer from Digikey,  they say part # is
> discontinued and refers to picstart plus, they then enter that #
> and it refers to the 16B1.    I am new to this pic thing and was
> looking forward to getting started now I am confused.  .... Does
> anyone out there know  what is happening?

Brian:

The old Picstarts have been discontinued, more-or-less... They're
still available as the "Picstart Lite" in countries that impose
large duties on imported products, but here in the States, the old
Picstarts have been replaced by the Picstart Plus, which programs
ALL the PICs.

Digi-Key should have the situation under control, but if you're
having problems with them, call your local Microchip distributor and
order a Picstart Plus from them.

-Andy

=== Andrew Warren - EraseMEfastfwdspam_OUTspamTakeThisOuTix.netcom.com                 ===
=== Fast Forward Engineering - Vista, California          ===
===                                                       ===
=== Did the information in this post help you?  Consider  ===
=== contributing to the PICLIST Fund.  Details are at:    ===
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1996\12\20@050716 by Octavio Nogueira

flavicon
face
----------
> De: Jorge M. Cabral <Jorge.Cabralspamspam_OUTDEI.UMINHO.PT>
> Para: Multiple recipients of list PICLIST <@spam@PICLISTKILLspamspamMITVMA.MIT.EDU>
> Assunto: Re: Help:RS232-TTL <-> RS-232-C
> Data: Quinta-feira, Dezembro 19, 1996 09:35
>
> > do you have a negative supply?
> Yes, pin 20 of RS232 can by toggled to /~-12V.


This is very simple and works just fine

                +5V
               |
                e |    10K
               \_b____/\/\/\/\/\_____ to PIC
                c /
               | PNP
RS-232________|
               \
               /
               \  10K
               /
               |
               |
               -12V

My ASCII art is very bad but I think you can understand.

Octavio
========================================================
Octavio Nogueira
e-mail:   KILLspamnogueiraKILLspamspammandic.com.br
homepage: http://ourworld.compuserve.com/homepages/tato
voice/fax: +55 11 240-6474
"ProPic" The first Production PIC Programmer running in
Windows and under US$ 20.00.
========================================================

1996\12\20@201743 by ryan_h

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face
B. Davies wrote:
>
> In some threads recently I have read about microchip  no longer supporting
> certain programmers.   I tried today to order a picstart 16B1 programmer from
> Digikey,  they say part # is discontinued and refers to picstart plus, they
> then enter that # and it refers to the 16B1.    I am new to this pic thing
> and was looking forward to getting started now I am confused.  Is Digikey
> getting messed up or is there something more sinister afoot?   Seriously
> though I browsed microchips homepage 2 nights ago and down loaded a brochure
> for the 16B1.
> Does anyone out there know  what is happening?   Or do you know who I can
> contact?
>
> Thanks   Brian


I also was looking for this product.  I went to the Microchip home page
(http://www.microchip.com), and found out that they still have a listing of it
so I am looking for a new place to buy it from.  The also have list of
place that sell their products on the home page.

1996\12\21@064718 by Lynn Richardson

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face
I was serious.  I bought the Picstart Plus last summer because Microchip
said it would program ALL their pic chip products.  A few months later I
find I need to replace/change the firmware in the adaptor to program the
new 12C5xx parts.  I think it is fair to extrapolate that when Microchip
comes out with new PIC parts, further changes will be needed to the
firmware.  Or maybe there'll never be any new PIC parts? Hmmm... hadn't
though of that.

_____________________________________________
Lynn Richardson           | RemoveMElrichTakeThisOuTspamqni.com    \
Progress Instrument, Inc. | wa0znl.ampr.org  |
807 NW Commerce Drive     |  [44.46.176.3]   |
Lee's Summit, MO 64086    |                  |
(816)524-4442 F:246-4556  |                  /
---------------------------------------------

On Thu, 19 Dec 1996, Andrew Warren wrote:

{Quote hidden}

1996\12\21@070001 by Mike

flavicon
face
>I was serious.  I bought the Picstart Plus last summer because Microchip
>said it would program ALL their pic chip products.  A few months later I
>find I need to replace/change the firmware in the adaptor to program the
>new 12C5xx parts.  I think it is fair to extrapolate that when Microchip
>comes out with new PIC parts, further changes will be needed to the
>firmware.  Or maybe there'll never be any new PIC parts? Hmmm... hadn't
>though of that.

Might be that with the 12C5XX being the first of a whole new series of
serial programmable a basic firmware change was need to handle this. If
more PIC parts follow the existing programming protocols then I doubt
there will be a need to a firmware change.

Some-one did say there was an older version of the P+ perhaps now
you'll be ok (Until they come up with a CPU in a TO-92 pack).

Rgds

Mike

There is no a'priori reason that the ultimate truth will be interesting
or even useful, those moments of frustration during philosophical debate
would be replaced by the sheer terror which accompanies true knowledge.

1996\12\21@080135 by Lynn Richardson

flavicon
face
I can't imagine Microchip's product development being constrained to
creating only new parts still programmable by the Plus.  No money in it.

If I was calling the shots at Mchip, I'd confine the programming support
products to the lowest common denominator, DOS programs running on XTs
with 256k ram and a floppy disk drive, programming adaptors on the printer
port and still compatible with W95.  That way they'd get the widest
possible customer base while minimizing their support expenses.  I doubt
the profits on sales of Picstart Pluses, 16Bs, 16Cs or Lites pays the
costs of the programming support department.

Leave the bells and whistles program development systems (and risks) to
other specialty companies.

Another thing I'd do is look at gearing up for masked part production
ability.  There's no upward migration path at Mchip when my quantities are
getting obscene.  If I can save $1.50 per part at 20000 pcs/yr and mask
tooling charges are only $3000-$4000, I can easily justify the
redesign/program costs to use another brand's masked chip.

Don't get me wrong, I LIKE the Mchip parts, they're great!  But other
companies with good products have gone belly up.  Don't want to see it
happen to Mchip.

_____________________________________________
Lynn Richardson           | TakeThisOuTlrichEraseMEspamspam_OUTqni.com    \
Progress Instrument, Inc. | wa0znl.ampr.org  |
807 NW Commerce Drive     |  [44.46.176.3]   |
Lee's Summit, MO 64086    |                  |
(816)524-4442 F:246-4556  |                  /
---------------------------------------------

On Sat, 21 Dec 1996, Mike wrote:

{Quote hidden}

1996\12\21@140732 by fastfwd

face
flavicon
face
Lynn Richardson <RemoveMElrichspamTakeThisOuTqni.com> wrote:

> I bought the Picstart Plus last summer because Microchip said it
> would program ALL their pic chip products.  A few months later I
> find I need to replace/change the firmware in the adaptor to
> program the new 12C5xx parts.  I think it is fair to extrapolate
> that when Microchip comes out with new PIC parts, further changes
> will be needed to the firmware.

   Think what you like, Lynn... The truth, however, is that there
   are only a few programming algorithms that are shared among all
   the PIC procesors, and that's not intended to change.

   -Andy

=== Andrew Warren - fastfwdEraseMEspam.....ix.netcom.com                 ===
=== Fast Forward Engineering - Vista, California          ===
===                                                       ===
=== Custodian of the PICLIST Fund -- For more info, see:  ===
=== http://www.geocities.com/SiliconValley/2499/fund.html ===

1996\12\21@141600 by fastfwd

face
flavicon
face
Lynn Richardson <EraseMEPICLISTspamMITVMA.MIT.EDU> wrote:

> I can't imagine Microchip's product development being constrained to
> creating only new parts still programmable by the Plus.  No money in
> it.

   How do you figure, Lynn?

> If I was calling the shots at Mchip, I'd confine the programming
> support products to the lowest common denominator, DOS programs
> running on XTs with 256k ram and a floppy disk drive, programming
> adaptors on the printer port and still compatible with W95.

   Good thing you're not.

> Another thing I'd do is look at gearing up for masked part
> production ability.  There's no upward migration path at Mchip when
> my quantities are getting obscene.  If I can save $1.50 per part at
> 20000 pcs/yr and mask tooling charges are only $3000-$4000, I can
> easily justify the redesign/program costs to use another brand's
> masked chip.

   Microchip has been offering mask-ROM programming for years and
   years.  20K pieces per year, however, aren't what anyone would
   call "obscene" quantities.

> other companies with good products have gone belly up.  Don't want
> to see it happen to Mchip.

   Don't worry; it won't.

   -Andy

=== Andrew Warren - RemoveMEfastfwdEraseMEspamEraseMEix.netcom.com                 ===
=== Fast Forward Engineering - Vista, California          ===
===                                                       ===
=== Custodian of the PICLIST Fund -- For more info, see:  ===
=== http://www.geocities.com/SiliconValley/2499/fund.html ===

1996\12\21@163122 by John Payson

picon face
> >I was serious.  I bought the Picstart Plus last summer because Microchip
> >said it would program ALL their pic chip products.  A few months later I
> >find I need to replace/change the firmware in the adaptor to program the
> >new 12C5xx parts.  I think it is fair to extrapolate that when Microchip
> >comes out with new PIC parts, further changes will be needed to the
> >firmware.  Or maybe there'll never be any new PIC parts? Hmmm... hadn't
> >though of that.
>
> Might be that with the 12C5XX being the first of a whole new series of
> serial programmable a basic firmware change was need to handle this. If
> more PIC parts follow the existing programming protocols then I doubt
> there will be a need to a firmware change.
>
> Some-one did say there was an older version of the P+ perhaps now
> you'll be ok (Until they come up with a CPU in a TO-92 pack).

There really isn't any good way Microchip could have designed the 12C508 so
as to be programmable in old programmers without modification unless they
had pinned out the part as:

1 - /MClr [VPP]   8 - ?
2 - Vss           7 - VDD
3 - ?             6 - SDAT
4 - ?             5 - SCLK

and then had users insert the parts two pins from the bottom in the prog-
ramming socket.  Given the high likelihood of 'knackered' parts I'm just
as glad they didn't go that route.

On the other hand, I might have preferred, aesthetically, using an adapter
board to move the pins around.  In particular, using that approach you could
ensure that you gave the 12C508 very good power and ground connection whereas
with the current approach there is no such guarantee.  Also, the former
approach would have made a "production quality" programmer much more practi-
cal since only one pin would need variable voltage switching.

1996\12\23@122510 by John Magrane

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face
part 0 597 bytes
Microchip's claim to fame has been cost effective, quick to market OTP.
They must be doing something right since most others now try to copy
the program.

There is no part that I know of in their product line that been be had
at a savings of $1.50 per unit. I sell products to some customers in
500k units in OTP because the quick time to market and potential to add
on orders without another 12 week wait outweighs the small price
differential.

For the most cost sensitive applications, though, Microchip does offer
ROM options for many parts.

John Magrane
FAE Bell Industries
(408) 734-8570


1996\12\23@175835 by William Chops Westfield

face picon face
   If I was calling the shots at Mchip, I'd confine the programming support
   products to the lowest common denominator, DOS programs running on XTs
   with 256k ram and a floppy disk drive, programming adaptors on the printer
   port and still compatible with W95.  That way they'd get the widest
   possible customer base while minimizing their support expenses.

Maybe.  Who wants customers who can't afford $1000 for a new PC every 5
years? (and that's for "current generation" technology.  You can upgrade to
a reasonable 486 system for considerably less (~$90 for motherboard and
cpu), and I bought a used 386sx w VGA and 40Mb hard drive for under $40.))
I don't believe that this would actually minimize support costs, given that:

       1) there are more versions of DOS than of windows.
       2) part of what windows does is insulate you from a
          wider variety of hardware than DOS does.  Writing any
          sort of screen-oriented software for DOS is a pain.
          Serial support sucks too.
       3) people will complain that it doesn't work in their linux
          DOS window, or their Mac SOFTPC window, etc, etc...

BillW

1996\12\24@081606 by Lynn Richardson

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face
1 - Who can afford to miss a customer just because of economic snobbery?
Just because the rich USA city boys can afford to get a new PC every year
doesn't mean every potential Mchip customer can.  Small shoestring
startups can grow into major accounts.

2 - Dos versions? You'd be hard pressed to find anything running less than
3.1 and simple Dos programs would have no trouble with the later versions.
CGA text mode screen handling is stable and well known with several public
domain source code modules available in either asm, C or Turbo Pascal.
Mchip appears to have used Borland's TurboVision library in the Picstart
16B and 16C MPSTART programs, so they have the tools and the source code.
Developing another DOS MPSTART program for the Plus would have been a
modest patch. The serial com problems have been around a long time and the
fixes/work arounds published.  Most of the problem today is in the
variations in hardware.  Best to avoid serial and use the printer port.

3 - I've been complaining about MPLAB's problems with Windows 95. Problems
are just as (and maybe more) likely with W95/W3.1/WNT/WWG as DOS.
Microsoft doesn't seem to tell application programmers all they need to
know about their OSs to avoid problems. Eventually the bugs and pitfalls
will be identified/published and then MS will come out with a new OS that
starts the thing all over again.  They've been doing that since day one (I
remember MSDOS 1.0!).

_______________________________________________________________________
Lynn Richardson          | RemoveMElrichspam_OUTspamKILLspamqni.com    |Progress Instrument, Inc.|
Design Engineer          | wa0znl.ampr.org  |807 NW Commerce Drive    |
Circuit Design DC to 1GHz|  [44.46.176.3]   |Lee's Summit, MO 64086   |
Asm 6805, Z8, 8051, PIC  |                  |Phone: (816) 524-4442    |
C                        |                  |Fax: (816) 246-4556      |

On Mon, 23 Dec 1996, William Chops Westfield wrote:

{Quote hidden}

1996\12\24@111951 by Wireless Scientific

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At 7:12 AM 12/24/96, Lynn Richardson wrote:
>1 - Who can afford to miss a customer just because of economic snobbery?
>Just because the rich USA city boys can afford to get a new PC every year
>doesn't mean every potential Mchip customer can.  Small shoestring
>startups can grow into major accounts.


I run a small company and those decisions are very difficult to make. But
the plain fact remains, we are in business to stay in business and the
little guys unfortunately get the squeeze. So is it worth all the effort to
force backward compatibilty to DOS, I can't say.

But what it does allow are third party development opportunities which some
of you might undertake (if DOS is your passion). Many companies do fine
writing programs that the big guys have abandoned.


craig


Dr. Craig Hollabaugh
Wireless Scientific

1996\12\24@161826 by John Payson

picon face
> 2 - Dos versions? You'd be hard pressed to find anything running less than
> 3.1 and simple Dos programs would have no trouble with the later versions.

>               The serial com problems have been around a long time and the
> fixes/work arounds published.  Most of the problem today is in the
> variations in hardware.  Best to avoid serial and use the printer port.

For situations not needing high-throughput serial communications (and I
think a PIC programmer would qualify as such) it's possible to write
communications routines that'll work 'with anything' if you simply use
polled I/O rather than interrupts.  The one place this would be tricky is
that every byte of data sent to the PC has to be individually requested;
if that caveat is kept in mind, however, polled serial routines can run
effectively with practically no compatibility problems whatsoever.

1996\12\25@211352 by Larry G. Nelson Sr.

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At 09:19 AM 12/23/96 -0800, John Magrane wrote:
>> Another thing I'd do is look at gearing up for masked part
>> production ability.  There's no upward migration path at Mchip when
>> my quantities are getting obscene.  If I can save $1.50 per part at
>> 20000 pcs/yr and mask tooling charges are only $3000-$4000, I can
>> easily justify the redesign/program costs to use another brand's
>> masked chip.
>
I have clients that are saving considerable money with ROM based chips for
some of their products. The OTP is the big sell until the code is stabile
even with high volume. With OTP you can also customize quickly in your
production line without getting stuck with NRE costs or a pile of obsolete
product.

Larry G. Nelson Sr.
RemoveMEL.NelsonTakeThisOuTspamspamieee.org
http://www.ultranet.com/~nr

1996\12\26@205756 by Jim Robertson

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face
At 03:07 PM 12/24/96 -0600, you wrote:

>For situations not needing high-throughput serial communications (and I
>think a PIC programmer would qualify as such) it's possible to write
>communications routines that'll work 'with anything' if you simply use
>polled I/O rather than interrupts.  The one place this would be tricky is
>that every byte of data sent to the PC has to be individually requested;
>if that caveat is kept in mind, however, polled serial routines can run
>effectively with practically no compatibility problems whatsoever.


John,

Can you explain further on your claim 'with anything' and 'run effectively
with practically no compatibility problems whatsoever?'

Can you provide communication routines that are simply polled and will work
'with anything' for us.

I would like to see the same code used with Windows NT, WFWG, OS/2, unix
and DOS. I would really like to see how you can do it without the use of
higher operating system calls to by pass the problems with interrupts you
can't disable, virtual uarts, privileged I/O, multitasking etc etc....

It's not that I'm claim to know for certain if you can or can't and I would
hate to be seen to be doubting you, heaven forbid! I just haven't had
anyone else offer me so much hope for a long time.

I look for too seeing this revelation expanded upon.

Jim

1996\12\27@112226 by timetech

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face
Jim Robertson wrote:
>
> Can you explain further on your claim 'with anything' and 'run effectively
> with practically no compatibility problems whatsoever?'
>
> Can you provide communication routines that are simply polled and will work
> 'with anything' for us.
>
> I would like to see the same code used with Windows NT, WFWG, OS/2, unix
> and DOS.
<sniippp>

Jim:

We use polled and interrupt driven serial i/o routines that are written
in C and go directly to the hardware; these work fine in dos and (in a
dos box) in Win3.11 and Win95. Win-NT is a different beast, but if my
experience with real operating systems (which NT is getting to be one
of) is any predictor, the problems should be lessened, not made worse.
Our routines are compatible with various flavors of Unix once the C code
is translated. Dealing with the serial hardware is pretty straight
forward and pretty universal at that level, including the use of
interrupts. We haven't found any hardware our stuff doesn't work on yet.

You should be able to get exactly the same results by just following
your nose. (The NT stuff will require a different approach.)

Tom Rogers  VP-R&D  Time Tech inc.

1996\12\27@220914 by Jim Robertson

flavicon
face
At 11:20 AM 12/27/96 -0500, you wrote:
{Quote hidden}

Tom,

I noticed you said "polled and interrupt driven serial i/o." This
discussion was only on polled i/o not interrupt driven. I don't know how
much of what you are saying applies as you haven't given details on what
was applicable to your polled i/o routines.

Never the less, I believe you are confirming what I said. Sure, Windows 3.1
and Win95 can be straight forward enough but win95 can also cause great
problems on slower boxes. I have customers using my equipment with win95 on
a 25Mhz 486 and I can tell you it is not always as straight forward as you
would hope. Polled i/o still requires a "friendly environment" to work
properly.

You have conceded NT which is one I had upper most in mind, nothing about
OS/2 or windows for work groups though. OS/2 Warp uses a "virtual uart" and
while you think you are directly accessing the hardware, you are not in
fact. Therefore you are relying on OS/2 to be kind to your requirements.
Not always the case. I have no shortage of email here to demonstrate this
point.

As for your successes, sure it may be valid and is of interest to me, but I
have a 97-99% success rate with my programmers. It is the few failures that
blow away the sort of statements I was replying to and consume 99% of your
time dealing with serial communications. Currently, serial comms on the PC
is a really screwed up affair.

The bottom line is that simply using polled I/O is not a universal panacea
for serial communications and will not work on 'anything' and in every
case. I maintain the initial remarks were misleading and probably a guess
more than anything. Having accumulated a lot of experience (and lost a lot
of hair in the process,) this is something I do not need to make guesses
about.

Jim


--------------------------------------------------------
Jim Robertson
NEWFOUND ELECTRONICS
Email: EraseMEnewfoundspamspamspamBeGonene.com.au
http://www.labyrinth.net.au/~newfound

PHOENIX Shareware Picstart 16B upgrade coming.
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--------------------------------------------------------

1996\12\28@003259 by John Payson

picon face
{Quote hidden}

If you want your comms to be reliable, the first step is to ensure that the
remote device will not send more than one byte of information in response
to each byte which is sent to it.  If the remote is half-duplex, this may
produce about a 50 percent performance hit in some cases, but in many cases
the performance hit will not be nearly that much.  Note as well that if the
remote device can use "dedicated polling" for its serial I/O, it may be
possible to use very high baud rates reliably.

The key to the reliability lies in this fast: if the protocol allows at most
one character "in the pipe", and if it won't allow another one until the
first is processed (subject to timeout in the failure case) then it doesn't
matter how long the PC takes to process a byte--every byte will get where
it's going.

Aside from making the protocol robust even in environments where an operat-
ing system such as Win95 may steal clock cycles or even swap the application
to disk, using such a machanism eliminates the need for interrupts; while it
is not hard to get interrupts working 'most' of the time, using polled I/O
eliminates interrupt conflicts between COM1 and COM3, and between COM2 and
COM4; and it prevents the crashes that can occur when trying to use the ser-
ial port "opposite" the mouse port [i.e. the one that shares the same IRQ
line].

This approach of polled I/O will work on any operating system that allows
port reads/writes; it does not care about how long such port operations take
(though the longer such operations take the slower the program will run) nor
about the possibility of the program being swapped out at interrupt time.
The ONLY problem polled I/O has is usually that systems like Windows NT do
not let programs poke around with the hardware directly.  Even there, how-
ever, I have read [not tested] that adding 0x8000 to the port address of the
serial port will 'usually' work to access the port directly.

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