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My KIM-1 won't add two numbers.
Posted: Thu Apr 03, 2025 7:46 pm
by RonH
Hi Everyone,
I am new here.
My KIM-1 (Rev G) sat for about 45 years
Yesterday, it powered up fine.
I entered the program from the User Manual that adds 2 numbers.
I confirmed the program in memory.
But when I press GO, the display just goes black; the sum is not displayed.
I'm not sure about the correct position of the SST slide switch (my keyboard has that switch on the left).
But I do think I tried both positions with the same result.
(I'm going to double check this.)
My scope shows a good 1 MHz square wave between E-Y and E-22.
I don't know what else to check because I don't know much about how the board works.
I'll be reading the manuals.
Any suggestions, welcome!
RonH
Re: My KIM-1 won't add two numbers.
Posted: Thu Apr 03, 2025 8:16 pm
by barrym95838
Welcome, RonH!
I'm not a KIM-1 expert, but one should be here shortly. I believe that the display is continuously refreshed by the firmware, so if you crashed it with an improper exit you might have really added the numbers but are just unable to view the result.
Re: My KIM-1 won't add two numbers.
Posted: Thu Apr 03, 2025 8:26 pm
by BigEd
Welcome! This looks like the relevant part of the manual:
https://www.kim-1.com/usrman.htm#24
Was it the case that the display showed 0002 just before you pressed GO?
Re: My KIM-1 won't add two numbers.
Posted: Thu Apr 03, 2025 8:28 pm
by BigEd
Ah, we can follow the same process at
https://maksimkorzh.github.io/KIM-1/
the KIM-1 on the web.
Re: My KIM-1 won't add two numbers.
Posted: Thu Apr 03, 2025 8:50 pm
by BigEd
As Mike says, the most important part is the final jump back into the monitor.
You should I think have entered something like this:
Code: Select all
Address Hexdump Dissassembly
-------------------------------
$0002 18 CLC
$0003 A5 00 LDA $00
$0005 65 01 ADC $01
$0007 85 FA STA $FA
$0009 A9 00 LDA #$00
$000B 85 FB STA $FB
$000D 4C 4F 1C JMP $1C4F
So the bytes at 000D onwards should be 4C 4F 1C. But you say you did verify the memory content.
Edit: that listing/disassembly is the result of assembling this program:
Code: Select all
define VAL1 $00
define VAL2 $01
define POINTL $fa
define POINTH $fb
define START $1c4f
PROG: CLC
LDA VAL1
ADC VAL2
STA POINTL
LDA #00
STA POINTH
JMP START
Re: My KIM-1 won't add two numbers.
Posted: Thu Apr 03, 2025 9:16 pm
by RonH
It's ALIVE!
I'm not sure what the issue was.
When I went back and double checked, it worked on the first try.
I confirmed I knew what I was doing by changing the 2 numbers and correctly predicting the sum.
And wow! This is a great place!
Thank you guys for the quick replies.
Yes that's the program.
The simulator is great.
Next (tomorrow?) I will fix my wiring for the cassette interface and see if I can find a recorder.
I think I remember from back in the day a warning not to use one with automatic recording level control.
I also think I remember playing with the pot you are not supposed to touch.
So, this may take a bit of work.
Thanks again!
Re: My KIM-1 won't add two numbers.
Posted: Thu Apr 03, 2025 9:20 pm
by BigEd
Great news!
Re: My KIM-1 won't add two numbers.
Posted: Mon Apr 07, 2025 1:25 am
by 6502inside
Could be flaky RAM. KIMs are notorious for that. My original suitcase KIM-1 would have weird intermittent lockups when it heated up until the bad RAM chip failed completely, and had to be replaced. After that it's worked like a champ. If you can find one of Dwight Elvey's debug boards, those will help a *lot*.
Re: My KIM-1 won't add two numbers.
Posted: Mon Apr 07, 2025 7:11 am
by BigEd
Here's Hans Otten's page describing that board (links within!)
KIM-1 Diagnostic Board
Re: My KIM-1 won't add two numbers.
Posted: Sat Apr 12, 2025 11:21 am
by HansO
First things to do on a KIM-1 (see the sticker attached from my original KIM-1)
Fill in the vectors, so Break /Stop/NMI works works.
Clear decimal 00F1 to 00 at least
Then press Go.