Loading ...
Sorry, an error occurred while loading the content.

Troubleshooting an ELF 2K

Expand Messages
  • Chuck Bigham
    I recently finished building the ELF 2K that my wife bought me for my birthday, and just like the ELF I built back in 1977, I did something wrong and I can t
    Message 1 of 7 , Sep 1, 2009
    • 0 Attachment
      I recently finished building the ELF 2K that my wife bought me for my
      birthday, and just like the ELF I built back in 1977, I did something
      wrong and I can't figure out what it is.

      Here are the symptoms:

      1. When I run the EEPROM it stops with 88 showing in the display. The
      manual says this means "SRAM size wrong (no monitor data page)." I
      have a HM62256ALP-10 chip installed, a 32K x 8-bit static RAM. Any
      suggestions on what could be causing this?
      2. When I take JP4 off and try to toggle in a program the data
      display never changes from FF no matter what I put in the toggle
      switches. If I flip up the MP switch and toggle through the memory
      it looks like random garbage until I reset. It looks like the data
      input switches are stuck set high, but when I watch the switches
      with my multimeter I can see the level change when I flip the switch.

      Any suggestions gratefully accepted.

      Chuck
    • Bob Armstrong
      ... Did you install the DS1210 and battery? If not, did you bypass it as instructed in the manual? Bob
      Message 2 of 7 , Sep 2, 2009
      • 0 Attachment
        >I recently finished building the ELF 2K that my wife bought me for my
        >birthday, and just like the ELF I built back in 1977, I did something
        >wrong and I can't figure out what it is.

        >Here are the symptoms:

        Did you install the DS1210 and battery? If not, did you bypass it as
        instructed in the manual?

        Bob
      • Chuck Bigham
        I installed the DS1210, but I don t have a battery in the battery holder.
        Message 3 of 7 , Sep 2, 2009
        • 0 Attachment
          I installed the DS1210, but I don't have a battery in the battery holder.

          Bob Armstrong wrote:
          >
          >
          > >I recently finished building the ELF 2K that my wife bought me for my
          > >birthday, and just like the ELF I built back in 1977, I did something
          > >wrong and I can't figure out what it is.
          >
          > >Here are the symptoms:
          >
          > Did you install the DS1210 and battery? If not, did you bypass it as
          > instructed in the manual?
          >
          > Bob
          >
          > _
        • Bob Armstrong
          ... The DS1210 doesn t like being used without a battery. Bob
          Message 4 of 7 , Sep 2, 2009
          • 0 Attachment
            >I installed the DS1210, but I don't have a battery in the battery holder.

            The DS1210 doesn't like being used without a battery.

            Bob
          • svodyssey
            Thanks to Bob and some pointers that he gave me I was able to get my ELF2K up and running. Turns out I had two problems, one builing problem and one defective
            Message 5 of 7 , Sep 15, 2009
            • 0 Attachment
              Thanks to Bob and some pointers that he gave me I was able to get my ELF2K up and running. Turns out I had two problems, one builing problem and one defective part.

              I found a couple of connections on the IDC connector for the switch panel weren't secure. A couple of squeezes on the connector took care of the switches that weren't working.

              I couldn't get some memory locations to change, so I built a test harness with some Picaxe chips and discovered that my RAM chip was defective. The replacement came in the mail today, I put it in the ELF2K and it started working.

              If anyone's interested in the memory test harness, I've posted a brief description on my Web site:

              http://www.bramblyhill.com/post/RAM-Test-Rig.aspx

              Thanks,
              Chuck

              --- In cosmacelf@yahoogroups.com, Chuck Bigham <chuck@...> wrote:
              >
              > I recently finished building the ELF 2K that my wife bought me for my
              > birthday, and just like the ELF I built back in 1977, I did something
              > wrong and I can't figure out what it is.
            • mmmkdm1
              Well, I built my Elf2K. Everything works. Pixie, Monitor, Ram, Displays etc. I decided to build the switches. I ran into the data switches always returning FF
              Message 6 of 7 , Jan 22, 2012
              • 0 Attachment
                Well, I built my Elf2K. Everything works. Pixie, Monitor, Ram, Displays etc.
                I decided to build the switches. I ran into the data switches always returning FF problem. Run, MP, Input, Load seem to work. I checked connections between the pins and all seems correct. Even setting the MP and LOAD switches and pushing Input cycles thru memory correctly.
                I then did what the manual stated when removing the switch board and grounded 3,5,7,9,11,13,15,17 (and of course Input and Load) to make inp return 00. Didn't work.
                The monitor IN 4 command still returns FF.
                Can't seem to find the issue. I tried changing some chips out, like the 4044, 74HC244's. I didn't want to go further without finding out if you guys know where I could look.

                This small program from Short Course tut puts FF in 0003 when Input is pressed.
                0000 3F
                0001 00
                0002 6C
                0003 7B
                0004 00



                --- In cosmacelf@yahoogroups.com, "svodyssey" <chuck@...> wrote:
                >
                > Thanks to Bob and some pointers that he gave me I was able to get my ELF2K up and running. Turns out I had two problems, one builing problem and one defective part.
                >
                > I found a couple of connections on the IDC connector for the switch panel weren't secure. A couple of squeezes on the connector took care of the switches that weren't working.
                >
                > I couldn't get some memory locations to change, so I built a test harness with some Picaxe chips and discovered that my RAM chip was defective. The replacement came in the mail today, I put it in the ELF2K and it started working.
                >
                > If anyone's interested in the memory test harness, I've posted a brief description on my Web site:
                >
                > http://www.bramblyhill.com/post/RAM-Test-Rig.aspx
                >
                > Thanks,
                > Chuck
                >
                > --- In cosmacelf@yahoogroups.com, Chuck Bigham <chuck@> wrote:
                > >
                > > I recently finished building the ELF 2K that my wife bought me for my
                > > birthday, and just like the ELF I built back in 1977, I did something
                > > wrong and I can't figure out what it is.
                >
              • mmmkdm1
                Well, Well after 15hrs yesterday. getting up at 2:00 am today. (and of course after I posted this) i found it!! The GAL had one pin that looked perfect.
                Message 7 of 7 , Jan 22, 2012
                • 0 Attachment
                  Well, Well after 15hrs yesterday. getting up at 2:00 am today. (and of course after I posted this) i found it!! The GAL had one pin that looked perfect. Perfect cone and everything. But it wasn't touching the pad by a hairs gap. I saw it move in a 20X eye piece. Whew!!.

                  --- In cosmacelf@yahoogroups.com, "mmmkdm1" <patternsemerge@...> wrote:
                  >
                  > Well, I built my Elf2K. Everything works. Pixie, Monitor, Ram, Displays etc.
                  > I decided to build the switches. I ran into the data switches always returning FF problem. Run, MP, Input, Load seem to work. I checked connections between the pins and all seems correct. Even setting the MP and LOAD switches and pushing Input cycles thru memory correctly.
                  > I then did what the manual stated when removing the switch board and grounded 3,5,7,9,11,13,15,17 (and of course Input and Load) to make inp return 00. Didn't work.
                  > The monitor IN 4 command still returns FF.
                  > Can't seem to find the issue. I tried changing some chips out, like the 4044, 74HC244's. I didn't want to go further without finding out if you guys know where I could look.
                  >
                  > This small program from Short Course tut puts FF in 0003 when Input is pressed.
                  > 0000 3F
                  > 0001 00
                  > 0002 6C
                  > 0003 7B
                  > 0004 00
                  >
                  >
                  >
                  > --- In cosmacelf@yahoogroups.com, "svodyssey" <chuck@> wrote:
                  > >
                  > > Thanks to Bob and some pointers that he gave me I was able to get my ELF2K up and running. Turns out I had two problems, one builing problem and one defective part.
                  > >
                  > > I found a couple of connections on the IDC connector for the switch panel weren't secure. A couple of squeezes on the connector took care of the switches that weren't working.
                  > >
                  > > I couldn't get some memory locations to change, so I built a test harness with some Picaxe chips and discovered that my RAM chip was defective. The replacement came in the mail today, I put it in the ELF2K and it started working.
                  > >
                  > > If anyone's interested in the memory test harness, I've posted a brief description on my Web site:
                  > >
                  > > http://www.bramblyhill.com/post/RAM-Test-Rig.aspx
                  > >
                  > > Thanks,
                  > > Chuck
                  > >
                  > > --- In cosmacelf@yahoogroups.com, Chuck Bigham <chuck@> wrote:
                  > > >
                  > > > I recently finished building the ELF 2K that my wife bought me for my
                  > > > birthday, and just like the ELF I built back in 1977, I did something
                  > > > wrong and I can't figure out what it is.
                  > >
                  >
                Your message has been successfully submitted and would be delivered to recipients shortly.