when entering value 7 or 8, both LEDs are burning

[djatm...@gmail.com]

Hi all,

when entering dec 7 (001 000) or dec 8 (010 000) and entering with toggle "Load Add" and when enter dec 7 (001 000) or dec 8 (010 000) with toggle "Dep", in both LED lines (Progam Counter & Memory Address) both corresponding LEDs are lighting simultaneously (011 000).

Example: Switches to 000 000 001 000 -> press Load Add -> gives 000 000 011 000 in Program Counter.
Switches to 000 000 010 000 also outputs 000 000 011 000 in Program Counter.

same for Deo. and Memory Address line of LEDs.

Unfortunately I'm not an electronics guy, so I don't find the logic error.

Found some wrong soldering, which I corrected.
Does anyone have an idea, what the error could be or how do I check function of other LEDs?
When entering other values, everything looks well, only dec 7 and 8 had this issue.

Hope someone will understand my question, as I'm not into octal. My first computer had an Z80 proc. and after that I was using PC Clones back in the days :)

Thanks in advance for some hints.
Andy

[djatm...@gmail.com]

Forgot to mention, it's Rev. 2.2 2016-02-16

[Flavio Villanustre]

If both LEDs lit simultaneously on either entry, that could indicate a solder bridge. Test for continuity between the two LEDs on both sides (with the system off, of course). Visually inspect for any solder bridges (use a magnifying glass, if you have one).

I hope this helps.

Flavio

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[djatm...@gmail.com]

Hi Flavio,

yes, that was also my first thought, but I was wondering, why this happens on both LED lines, and  had a switch in mind, but because of the warning in building instructions, I tried to solder very quick to not burn a switch and contacts.
But will look for bridges for sure, as I already found one shorted LED...

Andy

[Flavio Villanustre]

That is a good point. The bridge could also be across switches, not just LEDs. Try the pidp8i-test program and see if the LEDs operate independently when it's testing columns and individual LEDs. If they are independent there, then the bridge must be across the switches. On the other hand, if both LEDs turn on and off synchronously, then the bridge must be across those LEDs.

Flavio

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[Andreas Kabus]

Very good point, seems I had overseen the pidp8i-test program. will give it a try, thank you!

Andy

Am 20.01.25 um 22:23 schrieb Flavio Villanustre:

[Flavio Villanustre]

My pleasure! You can test the switches too with that program. That way you will be absolutely sure.

Flavio

[djatm...@gmail.com]

Found some LED pin I missed while soldering, now all LEDs are on in the all LED on test.

With oidp8i-test I found out, that in column 4 and 5 both are on, all other lines and columns seems to be ok, one issue with switches: both switches under column 4 and 5 give output value of 0030 in the first octal column of test-output (A).

Any idea?
Perhaps I burnt one of the diodes?
Could possibly change 1-3, since there where 3 diodes more in the kit, than needed.

Andy

[Flavio Villanustre]

Hmm... check for solder bridges between the IC legs and in the Raspberry Pi connector area.

Flavio

To view this discussion visit https://groups.google.com/d/msgid/pidp-8/03506d91-fe83-448a-b707-0cc2b96c1203n%40googlegroups.com.

[djatm...@gmail.com]

tbh, could not find the issue and did not have the time to do so...

I found some minor issues that I fixed, now I changed the Pi 3 for an unused Zero 1 WH and a small 1A PSU and it is running Deeper Thought 2 very well.

The column issue is nearly not visible now.

I know that this is not its original purpose, but it is now standing in my living room, right next to the DJ mixer, blinking happily.
Nevertheless, I would like to thank you for your quick assistance, which is not a matter of course these days!

Best Regards
Andy

[Flavio Villanustre]

Andy, I'm very happy that it turned out well. And what you do with your PiDP-8 is up to you. I have it right behind me in my home office, happily blinking the idle pattern using "deeper" (you can google "github deeper pidp-8" to find it).

All the best,

Flavio

To view this discussion visit https://groups.google.com/d/msgid/pidp-8/17e568d0-07fc-441a-b2ee-5f3da199d2d1n%40googlegroups.com.

[timr...@gmail.com]

My PiDP-8i runs TSS/8 and I can watch the null job running by the AC counting.  This is the first type of computer I ever used back in junior high and high school.  I saw that running alot later when I was an operator for this system.  This is what got me to go into computers in college and my later career.  Such a simple machine but you could really do alot with it.