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Re: [midatlanticretro] Re: can a terminal damage a computer?

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  • Evan Koblentz
    ... There is precedent .... the time he declared our PDP-11/20 power supply dead, until yours truly observed that * the computer wasn t turned on *. :)
    Message 1 of 22 , Apr 6 7:44 PM
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      >> Bill might just be forgetting to turn the computer on!?

      There is precedent .... the time he declared our PDP-11/20 power supply
      dead, until yours truly observed that * the computer wasn't turned on *. :)
    • DuaneCraps
      Make sure that pin 1 is wired to chassis ground on both devices and is not open in your cable. this is separate from pin 7 , signal ground . If the connector
      Message 2 of 22 , Apr 7 5:37 AM
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        Make sure that pin 1 is wired to chassis ground on both devices and is not open in your cable. this is separate from pin 7 , signal ground . If the connector has a metal shell I would connect it to that too as, it will likely make contact before any of the pins.
         
        Duane
         
        Sent: Saturday, April 06, 2013 10:31 PM
        Subject: [midatlanticretro] Re: can a terminal damage a computer?
         
         

        --- In mailto:midatlanticretro%40yahoogroups.com, "hornbetw" <hornbetw@...> wrote:

        >
        > --- In
        href="mailto:midatlanticretro%40yahoogroups.com">mailto:midatlanticretro%40yahoogroups.com, David Gesswein <djg@> wrote:
        > >
        > > On Sat, Apr 06,
        2013 at 10:14:54PM -0000, joshbensadon wrote:
        > > > --- In
        href="mailto:midatlanticretro%40yahoogroups.com">mailto:midatlanticretro%40yahoogroups.com, "B. Degnan" <billdeg@> wrote:
        > > > >
        > > > > I have had a few computers fail while using my laptop as a terminal,
        > > > > recently.
        > > >
        > > > Ground
        yourself, ground the laptop, then plug into the host computer?
        > > >
        > > Running off batteries or if you have a 2 prong power adapter or it
        doesn't
        > > ground the power supply output the computer your attached
        to gets
        > > the energy from static zaps to the laptop.
        > >
        >
        > Most later model laptops with built in serial ports are
        not actually RS-232 compliant. Their serial ports are EIA-562 compliant. '562 has voltage swings around +/- 6 volts instead of +/- 12 volts. It's possible the lower swing might overstress older 1488/1489 chips.
        >
        >
        Tom

        It wouldn't affect the 1488 transmitter chips. I checked the data sheet for the the 1489 receiver chip, it's suppose to work from +/-2 to +/-30. I would agree that lesser voltages that put a digital chip into that gray area which is not 0 or 1 does stress them, however, in the case of the 1489, it has hysteresis built in (according to the data sheet for the National & TI chip) which has no "gray area".

        A good clue here would be to know if the damage happens after prolong usage or if the damage is happening right away when you first connect the laptop.

        We don't even know what the damage is yet. Bill might just be forgetting to turn the computer on!?

        :)J

      • Neil Cherry
        ... As other have noted, could be grounding problems. One thing I ve found greatly useful was to put the devices on a ground fault interrupt outlet. If there
        Message 3 of 22 , Apr 7 5:38 AM
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          On 04/06/2013 04:37 PM, B. Degnan wrote:
          > I have had a few computers fail while using my laptop as a terminal,
          > recently. Is there something a rs232 port can do to a computer to cause it
          > to fail, like the 1488/1489 drivers? Just seems odd. Corey was mentioning
          > that he had problems with his laptop after upgrading OS drivers, but I have
          > not done anything like that, I am using the same Win 2000 computer I have
          > had for years. Thinking I am just being superstitious but thought I'd
          > throw that one out there to see what others think.

          As other have noted, could be grounding problems. One thing I've found
          greatly useful was to put the devices on a ground fault interrupt
          outlet. If there is a ground problem then the GFI trips without destroying
          either the computer or the laptop. Also using a 1:1 transformer (Isolation
          transformer) is probably not a bad idea.

          --
          Linux Home Automation Neil Cherry ncherry@...
          http://www.linuxha.com/ Main site
          http://linuxha.blogspot.com/ My HA Blog
          Author of: Linux Smart Homes For Dummies
        • Mr Ian Primus
          It s going to be really rare for a terminal to damage a computer... beyond possibly burning out the 1488/1489 chips if there is something horribly wrong with
          Message 4 of 22 , Apr 7 6:02 AM
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            It's going to be really rare for a terminal to damage a computer... beyond possibly burning out the 1488/1489 chips if there is something horribly wrong with the terminal, wired wrong, etc. From what I've read, RS232 spec was designed so that any of the wires could be shorted to any of the others without damaging it. Not that it's foolproof, but...

            Now, there is an exception here if there is bad wiring in the building. If the computer and the terminal are on separate circuits, and one device isn't grounded, AND another fault occurs, then Bad Things can happen, because it's very possible to get a 120v differential between grounds. But, this will be a rather spectacular show of sparks and burning smells. Not a subtle device failure.

            I have many dozens of terminals, and I've never had one damage a computer.

            I had one weird occurrence several years ago while copying some files on an Apple IIe, however. I had the Apple II connected to the PC's RS232 port, and was using Kermit to transfer some stuff back and forth. And, this was one of those rare occasions when all of the covers were actually on everything. Cover on the PC, cover on the Apple II, monitor sitting on top. It was winter, so the air was dry, and in my computer room, I had one of those plastic chair mats, and a wheeled office chair with plastic wheels. This room is wired correctly, and properly grounded.

            I had been typing on the Apple II, moved a foot or two to do something else, went back, and habitually touched the metal bottom casing of the Apple to discharge any static. I get a respectable static zap from it, and then start typing. The serial line isn't responding. I spend a few minutes checking cables, and assume that I must have damaged the RS232 chips in the Apple with the static. Swap out the SSC in the Apple - nothing. Then I happen to try the other RS232 port on the computer - it works. So, I'd burned out the RS232 chip in the computer. The original SSC from the Apple was fine. The only damage was the PC.

            Later on, I happened to have the computer apart and there was a little crater in one of the RS232 line driver chips on the computer's motherboard. Interesting that I was able to blow out the chip like that, with static, on properly wired, correctly grounded machines.

            That has never happened since, and I can't explain it. You'd think the static would have damaged the Apple before the PC - and either way, the metal casing of the Apple is directly grounded. So is the casing of the PC.

            -Ian
          • Wesley Furr
            Perhaps the chip was marginal to begin with, thus a very small jolt was enough to cause it to fail? Seems odd it would generate in the Apple II (where you
            Message 5 of 22 , Apr 7 6:11 AM
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              Perhaps the chip was marginal to begin with, thus a very small jolt was
              enough to cause it to fail? Seems odd it would generate in the Apple II
              (where you touched) and go across the serial line without damaging the II...

              Wesley


              -----Original Message-----

              Later on, I happened to have the computer apart and there was a little
              crater in one of the RS232 line driver chips on the computer's motherboard.
              Interesting that I was able to blow out the chip like that, with static, on
              properly wired, correctly grounded machines.

              That has never happened since, and I can't explain it. You'd think the
              static would have damaged the Apple before the PC - and either way, the
              metal casing of the Apple is directly grounded. So is the casing of the PC.

              -Ian
            • B Degnan
              ... Thanks everyone for your useful suggestions. I was burying the ground line in a coffee can full of dirt but I should be adding water occasionally to keep
              Message 6 of 22 , Apr 7 6:32 AM
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                Evan Koblentz <evan@...> wrote:

                >>> Bill might just be forgetting to turn the computer on!?
                >
                >There is precedent .... the time he declared our PDP-11/20 power supply
                >
                >dead, until yours truly observed that * the computer wasn't turned on
                >*. :)
                >
                >
                >
                >------------------------------------
                >
                >Yahoo! Groups Links
                >
                >
                >
                Thanks everyone for your useful suggestions. I was burying the ground line in a coffee can full of dirt but I should be adding water occasionally to keep it a little muddy. That keeps the electrons flowing better.
                --
                Sent from my PDP 8/e.
              • joshbensadon
                ... lol. On this note, I think the electric company may be giving us used electrons (and charging us for new ones). I have no way to verify this, does anyone
                Message 7 of 22 , Apr 7 6:58 AM
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                  --- In midatlanticretro@yahoogroups.com, B Degnan <billdeg@...> wrote:

                  > >
                  > Thanks everyone for your useful suggestions. I was burying the ground line in a coffee can full of dirt but I should be adding water occasionally to keep it a little muddy. That keeps the electrons flowing better.
                  > --
                  > Sent from my PDP 8/e.

                  lol. On this note, I think the electric company may be giving us used electrons (and charging us for new ones). I have no way to verify this, does anyone here have an electron microscope?

                  :)J
                • Jeff Jonas
                  ... The Altair serial port blew one of those chips at the MARCH exhibit at the MAKER fair a few years ago. I m unsure if it was damaged there, or before. But
                  Message 8 of 22 , Apr 7 9:00 AM
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                    I defer to Ian's experience:

                    --- In midatlanticretro@yahoogroups.com, Mr Ian Primus <ian_primus@...> wrote:
                    > It's going to be really rare for a terminal
                    > to damage a computer... beyond possibly burning out the
                    > 1488/1489 chips if there is something horribly wrong
                    > with the terminal, wired wrong, etc.

                    The Altair serial port blew one of those chips
                    at the MARCH exhibit at the MAKER fair a few years ago.
                    I'm unsure if it was damaged there, or before.
                    But it sure ruined our day :-(

                    > Now, there is an exception here
                    > if there is bad wiring in the building.

                    As you vividly demonstrated at VCF with your Prime :-/
                    Perhaps I ought to demonstrate my
                    fiber optic RS232 adapters.
                    No metal between the systems,
                    and it can reach over a km without repeaters!

                    > I had one weird occurrence several years ago
                    > while copying some files on an Apple IIe, however ...
                    [static zap]
                    > So, I'd burned out the RS232 chip in the [PC] computer.

                    It's a crime not to socket those chips.

                    <mild rant>
                    The Univac is made up of hundreds, perhaps thousands of
                    teeny PC boards because it required constant maintenance.
                    Even televisions of the 70s were modular.
                    But now everything's surface mount
                    and so highly integrated into the motherboard
                    that the mobo is considered a FRU (field replaceable unit).
                    Happily, my car is not that way (yet!)

                    <slightly off topic>
                    Using a laptop/netbook/tablet (with software terminal emulation) with a USB to RS232 adapter sounds reasonably safe because the external adapter is the only thing at risk. Sadly, the Trenton Computer Fest's flea mkt is too small to offer them cheap as in years past :-(

                    There are 2 chips inside those dongles
                    - a FTDI FT232RL USB to serial adapter (or Prolific part)
                    but that's 5V TTL serial
                    (Adafruit's FTDI friend is just that chip
                    http://www.adafruit.com/products/284 )
                    - a Maxim MAX232 driver/buffer for TTL to RS232 levels
                    with built in power supply so it's +5V only
                    (also available as a teeny board:
                    http://www.mikroe.com/add-on-boards/communication/max232/ )

                    I just soldered up a RS232 to current loop adapter should MARCH need to interface to a current loop terminal.
                    It's not opto-ioslated but it was good enough to be a kit!

                    I'm unsure when or if I'll ever interface Bluetooth to that for wireless links to the vintage TTY.

                    -- jeff jonas
                  • B Degnan
                    ... think. ... greatly useful was to put the devices on a ground fault interrupt outlet. If there is a ground problem then the GFI trips without destroying
                    Message 9 of 22 , Apr 7 10:16 AM
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                      On 04/06/2013 04:37 PM, B. Degnan wrote:
                      >> I have had a few computers fail while using my laptop as a terminal,
                      >> recently. Is there something a rs232 port can do to a computer to
                      >> cause it to fail, like the 1488/1489 drivers? Just seems odd. Corey
                      >> was mentioning that he had problems with his laptop after upgrading OS
                      >> drivers, but I have not done anything like that, I am using the same
                      >> Win 2000 computer I have had for years. Thinking I am just being
                      >> superstitious but thought I'd throw that one out there to see what others
                      think.

                      >As other have noted, could be grounding problems. One thing I've found
                      greatly useful was to put the devices on a ground fault interrupt outlet. If
                      there is >a ground problem then the GFI trips without destroying either the
                      computer or the laptop. Also using a 1:1 transformer (Isolation
                      >transformer) is probably not a bad idea.

                      --------------------
                      ------------
                      ---

                      But seriously, my problems are all independent of each other. I do
                      everything through the grounded power supply of a battery backup with surge
                      protector so I would think I would get bad news lights if there was a
                      problem. I often solder at a different station than my laptop terminal.

                      The 1488/1489's do die, and I have had to replace a few for sure. Better
                      these than other parts.

                      I have other devices that are quite stable with my laptop as the terminal.
                      I think in my case it's just the computers/devices themselves, I try to not
                      to short things but I am not the most dexterous.

                      Bill
                    • Dave McGuire
                      ... [raises hand] I do. However, inspecting electrons with an electron microscope is tough, because you have to stain them for them to become visible. I once
                      Message 10 of 22 , Apr 7 10:44 AM
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                        On 04/07/2013 09:58 AM, joshbensadon wrote:
                        >> Thanks everyone for your useful suggestions. I was burying the ground
                        >> line in a coffee can full of dirt but I should be adding water
                        >> occasionally to keep it a little muddy. That keeps the electrons
                        >> flowing better.
                        >
                        > lol. On this note, I think the electric company may be giving us used
                        > electrons (and charging us for new ones). I have no way to verify this,
                        > does anyone here have an electron microscope?

                        [raises hand] I do.

                        However, inspecting electrons with an electron microscope is tough, because
                        you have to stain them for them to become visible. I once had a bottle of
                        stain that was made from quarks and muons, but the guy who sold it to me (who
                        had the oddest green scaly skin) isn't answering his phone anymore.

                        -Dave

                        --
                        Dave McGuire, AK4HZ
                        New Kensington, PA
                      • joshbensadon
                        ... Perhaps the static only shorted one transistor, but if that transistor was the constant current source (now unlimited current source) for some other
                        Message 11 of 22 , Apr 7 1:18 PM
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                          --- In midatlanticretro@yahoogroups.com, Mr Ian Primus <ian_primus@...> wrote:
                          > Later on, I happened to have the computer apart and there was a little crater in one of the RS232 line driver chips on the computer's motherboard. Interesting that I was able to blow out the chip like that, with static, on properly wired, correctly grounded machines.

                          Perhaps the static only shorted one transistor, but if that transistor was the constant current source (now unlimited current source) for some other transistors... then it's game on!

                          :)J
                        • joshbensadon
                          ... I think the best advice is to ground yourself more often. Like Ian said, he would touch metal before computer. I have personally seen in my professional
                          Message 12 of 22 , Apr 7 1:28 PM
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                            --- In midatlanticretro@yahoogroups.com, "B Degnan" <billdeg@...> wrote:
                            >
                            > But seriously, my problems are all independent of each other. I do
                            > everything through the grounded power supply of a battery backup with surge
                            >
                            > The 1488/1489's do die, and I have had to replace a few for sure. Better
                            > these than other parts.
                            >
                            > I have other devices that are quite stable with my laptop as the terminal.
                            > I think in my case it's just the computers/devices themselves, I try to not
                            > to short things but I am not the most dexterous.
                            >
                            > Bill

                            I think the best advice is to ground yourself more often. Like Ian said, he would touch metal before computer.

                            I have personally seen in my professional work how some people are more likely to create a static charge. I don't know if it's clothes, physical chemistry or personality but there is a definite difference.

                            Before you work on that COSMAC Microkit, you better touch wood and metal!

                            :)J
                          • DuaneCraps
                            Josh, Unless you have a DC feed from the power co., you are not getting any new electrons , only the same ones jogged back and forth. You might, however, be
                            Message 13 of 22 , Apr 7 2:33 PM
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                              Josh,
                               
                              Unless you have a DC feed from the power co., you are not getting any new electrons , only the same ones jogged back and forth. You might, however,  be sharing some with your neighbors who are on the same transformer. It might be worthwhile to invest in a whole house isolation transformer to assure that  you don’t get defective electrons from your neighbors. Can’t be too careful these days.
                               
                              Duane
                               
                              Sent: Sunday, April 07, 2013 9:58 AM
                              Subject: [midatlanticretro] Re: can a terminal damage a computer?
                               
                               

                              --- In mailto:midatlanticretro%40yahoogroups.com, B Degnan <billdeg@...> wrote:

                              > >
                              > Thanks everyone for
                              your useful suggestions. I was burying the ground line in a coffee can full of dirt but I should be adding water occasionally to keep it a little muddy. That keeps the electrons flowing better.
                              > --
                              > Sent from my PDP
                              8/e.

                              lol. On this note, I think the electric company may be giving us used electrons (and charging us for new ones). I have no way to verify this, does anyone here have an electron microscope?

                              :)J

                            • corey986
                              Yep I had a terminal Pop the serial driver chips, but the terminal was apparently hacked . When I found a switch inside that I flipped, it stopped killing
                              Message 14 of 22 , Apr 7 4:38 PM
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                                Yep I had a terminal Pop the serial driver chips, but the terminal was apparently "hacked". When I found a "switch" inside that I flipped, it stopped killing drivers.

                                So in my case you could say the 1488/1489 drivers were not victims of normal circumstances, but of a short or mis-wiring.

                                In the end no biggie. I have a bunch of NOS drivers for my 3P+S, it's just my sio-A MITS serial card I'm won't risk on an unknown terminal.

                                Cheers,
                                Corey

                                --- In midatlanticretro@yahoogroups.com, "B. Degnan" <billdeg@...> wrote:
                                >
                                > I have had a few computers fail while using my laptop as a terminal,
                                > recently. Is there something a rs232 port can do to a computer to cause it
                                > to fail, like the 1488/1489 drivers? Just seems odd. Corey was mentioning
                                > that he had problems with his laptop after upgrading OS drivers, but I have
                                > not done anything like that, I am using the same Win 2000 computer I have
                                > had for years. Thinking I am just being superstitious but thought I'd
                                > throw that one out there to see what others think.
                                > b
                                >
                              • joshbensadon
                                The PC Museum here in Ontario has an IMSAI 8080 that I plan to get operational next weekend. It doesn t have the original 8080 board and without it the front
                                Message 15 of 22 , Apr 7 6:12 PM
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                                  The PC Museum here in Ontario has an IMSAI 8080 that I plan to get operational next weekend. It doesn't have the original 8080 board and without it the front panel can't work, so I've built a replacement 8080A cpu card and loaded it with RAM, I/O, and a Disk Emulator.

                                  Does anyone have any CP/M software I can run on it for a decent demo? Wumpus perhaps?

                                  Thanks,
                                  Josh
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