PAL-2 built, running program causes LEDs to blank out

[John Calhoun]

I've tried a couple small programs. Made sure they were correct. Then go to 0200 and hit GO. LED's just blank out. I hit RS and LEDs are back, code is still there.

DIP switches are set to defaults suggested. Power if from 5V bench power supply (1.2A) running into the Application pins A and 1.

Any clue where I should start to troubleshoot?

[Hans Otten]

The PAL-2 looks fine if the LEDs light up and you can use the keypad to enter a program. That means the KIM monitor can use the hardware.

What did your small programs look like? Did they end with a JMP to the KIM monitor? 

LEDs going blank is expected when you start a program , it is the programs task to keep them alive.

Try this very simple program:

Enter FF at 0300

0200 A9 11

0202 8D 00 03

0200 G

Hit go. reset and inspect 0300 , should be 11 now

Now you have proof the PAL-2 is running programs.

Hans

[John Calhoun]

Thanks, Hans.

When I try your simple program, 0300 remains FF. Odd.

[Neil Andretti]

no magic smoke. phew.

It's up and running!

WOHOOOOOOO

[John Calhoun]

Have checked and double checked components, reflowed all the solder on the bottom side of the PCB, swapped the chips that I could with my working PAL-1. Still at a loss for why it does not execute a program when it runs.

There are four IC's I have not been able to swap because I have no substitute: U5, U7, U10 and U22. My focus is on U5, the EEPROM.

Is the EEPROM the "programmed" chip? Does it sound possible that the chip could be incorrectly programmed (or perhaps was scrambled from static discharge)?

Could a bad EEPROM cause execution to fail?

[Hans Otten]

Just to be sure: the SST switch is in the right position? 

[GN Liu]

The EEPROM is programmed with the KIM-1 monitor code and checked before packaging. If the EEPROM is faulty, the system will not power up normally. However, if the system responds to reset, ‘GO,’ and address entry, I believe the EEPROM and its data are functioning correctly.

The U22 will not be involved in the operation if you configure the system to the default setting (Fully RAM). 

You can try manually altering some RAM data and then checking it to see if U7 is working correctly.

and as Hans mentioned, the SST switch may cause the system to be unable to run programs.

[John Calhoun]

Oh wait.

So I had the ON SST switch to the left, assuming to the right was Single-Step. I switch to the right and we're running.

PAL-II #5 is running. Thanks, everyone!

And now to trey and get serial working.... (Kind of having a hard time finding the right combo of software + cables on MacOS.)

[Nils Andreas]

Hahahahahaahahahaah.  

great

Fixed this one. 

Von meinem iPhone gesendet

Am 07.02.2025 um 17:13 schrieb John Calhoun <softd...@gmail.com>:

Oh wait.

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[Hans Otten]

Folks, remember

You have to fill in the NMI vector and CLD after Power on and Reset before you do anything with your KIM-1. 

00F1 00 (Clear Decimal flag set) 

17FA-FB  00 1C NMI required for ST and SST

John had the SST switch to on and not filled in the NMI vector, so the LEDS went blank, the KIM-1 had crashed. Otherwise he would have seen the KIM-1 stepping his program.

(See the User manual Chapter 4)