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Testing 1802

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  • johngodsey@rocketmail.com
    I just got an 1802ace off of ebay and while I wait for my other parts to come in I was wondering if there was a good way to test the chip to be sure it works.
    Message 1 of 9 , Apr 16, 2011
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      I just got an 1802ace off of ebay and while I wait for my other parts to come in I was wondering if there was a good way to test the chip to be sure it works. I'm kinda paranoid about frying the cmos chips with static electricity.
    • Lee Hart
      ... Your best bet is probably to plug it into a known working circuit board, and see if it works. The 1802 is not especially static sensitive. Normal handling
      Message 2 of 9 , Apr 16, 2011
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        On 4/16/2011 2:27 PM, johngodsey@... wrote:
        > I just got an 1802ace off of ebay and while I wait for my other parts to come in I was wondering if there was a good way to test the chip to be sure it works. I'm kinda paranoid about frying the cmos chips with static electricity.

        Your best bet is probably to plug it into a known working circuit board,
        and see if it works.

        The 1802 is not especially static sensitive. Normal handling for CMOS
        parts is adequate. If the chip has been damaged by static, one way to
        detect it is by putting a microammeter in the power supply, and see how
        much current it draws with all the outputs open and all the inputs
        either grounded or high. Current consumption should be under a microamp.

        --
        Lee A. Hart | Ring the bells that still can ring
        814 8th Ave N | Forget the perfect offering
        Sartell MN 56377 | There is a crack in everything
        leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
      • Bob Armstrong
        ... On the same subject, has anybody ever seen any CPU diagnostics for the 1802? I m thinking of some firmware that exercises all the instructions, internal
        Message 3 of 9 , Apr 16, 2011
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          > Lee Hart [leeahart@...] wrote:
          >Your best bet is probably to plug it into a known working circuit board,
          >and see if it works.

          On the same subject, has anybody ever seen any CPU diagnostics for the
          1802? I'm thinking of some firmware that exercises all the instructions,
          internal registers and data paths in a systematic way. This is overkill for
          the original poster's question about testing a 1802 chip, but it would be
          useful people writing emulators and simulators.

          Bob Armstrong
        • Lee Hart
          ... We had such a tester at Tech Micro for the BASYS boards. Basically, it was a ROM with a test program that as you say, used every instruction. It also
          Message 4 of 9 , Apr 16, 2011
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            On 4/16/2011 5:01 PM, Bob Armstrong wrote:
            >> Lee Hart [leeahart@...] wrote:
            >> Your best bet is probably to plug it into a known working circuit board,
            >> and see if it works.
            >
            > On the same subject, has anybody ever seen any CPU diagnostics for the
            > 1802? I'm thinking of some firmware that exercises all the instructions,
            > internal registers and data paths in a systematic way. This is overkill for
            > the original poster's question about testing a 1802 chip, but it would be
            > useful people writing emulators and simulators.

            We had such a tester at Tech Micro for the BASYS boards. Basically, it
            was a ROM with a test program that as you say, used every instruction.
            It also tested RAM, and tested I/O (by having all the outputs looped
            back to the inputs). But it's not generally useful unless you have the
            same board with the same memory and I/O.

            --
            Lee A. Hart | Ring the bells that still can ring
            814 8th Ave N | Forget the perfect offering
            Sartell MN 56377 | There is a crack in everything
            leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
          • johngodsey@rocketmail.com
            So another quick question. I see a lot of elfs (elves?) built with the ICs exposed. Do you have to worries about static as much when the chips are in the
            Message 5 of 9 , Apr 19, 2011
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              So another quick question. I see a lot of elfs (elves?) built with the ICs exposed. Do you have to worries about static as much when the chips are in the board? Does the rest of the circuit help absorb it or what?

              --- In cosmacelf@yahoogroups.com, Lee Hart <leeahart@...> wrote:
              >
              > On 4/16/2011 5:01 PM, Bob Armstrong wrote:
              > >> Lee Hart [leeahart@...] wrote:
              > >> Your best bet is probably to plug it into a known working circuit board,
              > >> and see if it works.
              > >
              > > On the same subject, has anybody ever seen any CPU diagnostics for the
              > > 1802? I'm thinking of some firmware that exercises all the instructions,
              > > internal registers and data paths in a systematic way. This is overkill for
              > > the original poster's question about testing a 1802 chip, but it would be
              > > useful people writing emulators and simulators.
              >
              > We had such a tester at Tech Micro for the BASYS boards. Basically, it
              > was a ROM with a test program that as you say, used every instruction.
              > It also tested RAM, and tested I/O (by having all the outputs looped
              > back to the inputs). But it's not generally useful unless you have the
              > same board with the same memory and I/O.
              >
              > --
              > Lee A. Hart | Ring the bells that still can ring
              > 814 8th Ave N | Forget the perfect offering
              > Sartell MN 56377 | There is a crack in everything
              > leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
              >
            • Lee Hart
              ... Suppose a chip is naked and sitting loose on a wooden table. All pins are roughly at ground potential due to the slight conductivity of the wood (due to
              Message 6 of 9 , Apr 19, 2011
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                On 4/19/2011 10:22 AM, johngodsey@... wrote:
                > So another quick question. I see a lot of elfs (elves?) built with the ICs exposed. Do you have to worries about static as much when the chips are in the board? Does the rest of the circuit help absorb it or what?

                Suppose a chip is "naked" and sitting loose on a wooden table. All pins
                are roughly at ground potential due to the slight conductivity of the
                wood (due to humidity and moisture in the wood).

                You walk across the carpet (building up a 1000v static charge), and
                reach down to pick up the chip. The first pin you touch is instantly
                elevated to 1000v. The other pins have what amounts to a high resistance
                connection to ground.

                You now have a voltage divider with 1000v across. The desk's
                "resistance" and the chip's leakage resistance. Though both are many
                megohms, it's easy to get more than 30v across pins on the chip. That's
                all it takes to blow holes in the microscopic transistors. ZAP! Bad chip.

                If the chip is on a board, things are better. You have a bypass
                capacitor between each chip's VDD and VSS terminals. All the chips have
                internal diodes between each pin, and VDD and VSS. They insure than the
                only way to exceed 30v between any two pins is for 30v to appear across
                the bypass capacitor. Static discharges have high voltage, but very
                little energy. A 1000v static spark from your finger to one lead of a
                0.1uF capacitor won't even raise it to 1 volt.

                Additionally, each trace probably connects to two or more pins. This
                spreads the "hit" over several sets of protection diodes and chips. You
                may also have resistors or capacitors on the pins, which add further
                protection.

                You can still blow the chip, with a really *big* static discharge, and
                if you're poking the chip with a metal tool to get a really good
                connection. But, it's far less likely to damage the chip on a board.

                --
                Lee A. Hart | Ring the bells that still can ring
                814 8th Ave N | Forget the perfect offering
                Sartell MN 56377 | There is a crack in everything
                leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
              • johngodsey@rocketmail.com
                Excellent explanation thanks!
                Message 7 of 9 , Apr 19, 2011
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                  Excellent explanation thanks!

                  --- In cosmacelf@yahoogroups.com, Lee Hart <leeahart@...> wrote:
                  >
                  > On 4/19/2011 10:22 AM, johngodsey@... wrote:
                  > > So another quick question. I see a lot of elfs (elves?) built with the ICs exposed. Do you have to worries about static as much when the chips are in the board? Does the rest of the circuit help absorb it or what?
                  >
                  > Suppose a chip is "naked" and sitting loose on a wooden table. All pins
                  > are roughly at ground potential due to the slight conductivity of the
                  > wood (due to humidity and moisture in the wood).
                  >
                  > You walk across the carpet (building up a 1000v static charge), and
                  > reach down to pick up the chip. The first pin you touch is instantly
                  > elevated to 1000v. The other pins have what amounts to a high resistance
                  > connection to ground.
                  >
                  > You now have a voltage divider with 1000v across. The desk's
                  > "resistance" and the chip's leakage resistance. Though both are many
                  > megohms, it's easy to get more than 30v across pins on the chip. That's
                  > all it takes to blow holes in the microscopic transistors. ZAP! Bad chip.
                  >
                  > If the chip is on a board, things are better. You have a bypass
                  > capacitor between each chip's VDD and VSS terminals. All the chips have
                  > internal diodes between each pin, and VDD and VSS. They insure than the
                  > only way to exceed 30v between any two pins is for 30v to appear across
                  > the bypass capacitor. Static discharges have high voltage, but very
                  > little energy. A 1000v static spark from your finger to one lead of a
                  > 0.1uF capacitor won't even raise it to 1 volt.
                  >
                  > Additionally, each trace probably connects to two or more pins. This
                  > spreads the "hit" over several sets of protection diodes and chips. You
                  > may also have resistors or capacitors on the pins, which add further
                  > protection.
                  >
                  > You can still blow the chip, with a really *big* static discharge, and
                  > if you're poking the chip with a metal tool to get a really good
                  > connection. But, it's far less likely to damage the chip on a board.
                  >
                  > --
                  > Lee A. Hart | Ring the bells that still can ring
                  > 814 8th Ave N | Forget the perfect offering
                  > Sartell MN 56377 | There is a crack in everything
                  > leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
                  >
                • johngodsey@gmail.com
                  Another quicky of a question. When you press and hold the IN button it won t continue on till it s been released right? I accidently got a push button that
                  Message 8 of 9 , Apr 25, 2011
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                    Another quicky of a question. When you press and hold the IN button it won't continue on till it's been released right? I accidently got a push button that clicks in and you have to click again to release it.

                    --- In cosmacelf@yahoogroups.com, "johngodsey@..." <johngodsey@...> wrote:
                    >
                    > Excellent explanation thanks!
                    >
                    > --- In cosmacelf@yahoogroups.com, Lee Hart <leeahart@> wrote:
                    > >
                    > > On 4/19/2011 10:22 AM, johngodsey@ wrote:
                    > > > So another quick question. I see a lot of elfs (elves?) built with the ICs exposed. Do you have to worries about static as much when the chips are in the board? Does the rest of the circuit help absorb it or what?
                    > >
                    > > Suppose a chip is "naked" and sitting loose on a wooden table. All pins
                    > > are roughly at ground potential due to the slight conductivity of the
                    > > wood (due to humidity and moisture in the wood).
                    > >
                    > > You walk across the carpet (building up a 1000v static charge), and
                    > > reach down to pick up the chip. The first pin you touch is instantly
                    > > elevated to 1000v. The other pins have what amounts to a high resistance
                    > > connection to ground.
                    > >
                    > > You now have a voltage divider with 1000v across. The desk's
                    > > "resistance" and the chip's leakage resistance. Though both are many
                    > > megohms, it's easy to get more than 30v across pins on the chip. That's
                    > > all it takes to blow holes in the microscopic transistors. ZAP! Bad chip.
                    > >
                    > > If the chip is on a board, things are better. You have a bypass
                    > > capacitor between each chip's VDD and VSS terminals. All the chips have
                    > > internal diodes between each pin, and VDD and VSS. They insure than the
                    > > only way to exceed 30v between any two pins is for 30v to appear across
                    > > the bypass capacitor. Static discharges have high voltage, but very
                    > > little energy. A 1000v static spark from your finger to one lead of a
                    > > 0.1uF capacitor won't even raise it to 1 volt.
                    > >
                    > > Additionally, each trace probably connects to two or more pins. This
                    > > spreads the "hit" over several sets of protection diodes and chips. You
                    > > may also have resistors or capacitors on the pins, which add further
                    > > protection.
                    > >
                    > > You can still blow the chip, with a really *big* static discharge, and
                    > > if you're poking the chip with a metal tool to get a really good
                    > > connection. But, it's far less likely to damage the chip on a board.
                    > >
                    > > --
                    > > Lee A. Hart | Ring the bells that still can ring
                    > > 814 8th Ave N | Forget the perfect offering
                    > > Sartell MN 56377 | There is a crack in everything
                    > > leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
                    > >
                    >
                  • Lee Hart
                    ... In Load mode that s correct. It s normally wired so releasing the button does the actual loading. In Run mode, the IN button is just the EF4 flag line.
                    Message 9 of 9 , Apr 26, 2011
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                      On 4/25/2011 5:22 PM, johngodsey@... wrote:
                      > Another quicky of a question. When you press and hold the IN button it won't continue on till it's been released right? I accidently got a push button that clicks in and you have to click again to release it.

                      In Load mode that's correct. It's normally wired so releasing the button
                      does the actual loading.

                      In Run mode, the IN button is just the EF4 flag line. What it does
                      depends on the software that is running.

                      --
                      Lee A. Hart | Ring the bells that still can ring
                      814 8th Ave N | Forget the perfect offering
                      Sartell MN 56377 | There is a crack in everything
                      leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
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