KIM-1 Troubleshooting

[Jeff Nay]

I have recently started trouble shooting a REV G KIM-1 for a friend of mine. Most of the people who have been invited to this group, may already be familiar with my efforts, to determine if the 6530-002 may be the problem.

I created a simple bread board and connected the 6530-002 that I want to test on it and wired it to my working KIM-1.

I had determined that I could use K4 ($1000) for the ROM and K2 ($800+A9,A8+A6) ($oB40) for the I/O timer.

I have received a lot of good information from Hans and from from Youtube Channel Host Code Monkey King.

I thought I had it all figured out, so I wired it all up and hooked it up to my KIM-1, but my KIM-1 would not start with that board attached. So, maybe someone can take a look at my wiring diagram and see where I may have made a mistake. Or is it possible that I can not test the 6530-002 using this setup?

[Jeff Nay]

I added this conversation, before I ever added any members... Maybe this will move this conversation to the main groups conversation.

[Hans Otten]

Circuit looks good, logic makes sense. 

Perhaps the 6530-002 is that faulty on the breadboard, preventing databus/address/bus/RW/Phi2/Reset to operate? 
Did you check any of those? 

I would suggest: (with power off in between each step!)

- First test with only ground VCC.

- Then add one by one Phi2, Reset. R/W

- Next the address bus  

- Then databus 

- Last  connect Kx  lines one by one.

Somewhere in these steps your KIM-1 will stop booting.  

[Jeff M. Nay]

Yes, I did check all those control lines on the non-working system. Actually I did not look at the R/W.

 

Great suggestion.

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[Hans Otten]

I hope that checking one by one on your working KIm-1 with breadboard 6530-002 will show something.

[Jeff Nay]

I was able to get the 6530-002 test board working. I think I had K2 going to RS0 and K4 going to CS1, which is reversed. When I repeated that mistake, my KIM-1 would not boot up. Don't know why.

Anyway, I am now able to access the ROM that I am testing at $1000.  I looked specifically at address $13FC ($1FFC) Where I should see a 22h followed by a 1Ch the address used to Start the KIM-1 after Reset.

I did not find that value there, instead I found FFs. So I jumped to $1100, $1200, $1300. and everything looked pretty good at those addresses. So I started single stepping from $1300 and ran into a problem starting

at address $1308($1F08).

The thing is, where they differ, the code on my test ROM looks like actual good Hex code, not just random garbage. until I get closer to the end of the ROM, where it does start to look more like garbage.

With ($1FFC) $13FC not going to $1C22, and the deviation in code, that looks like good coding. I was thinking that this could have been a customized ROM, built for the system that it came out of. Which was some

kind of Radio Repeater system.

I have asked the owner to look further into the system, and see if there may have been another ROM on board. It would be hilarious if there were another 6530-002 .

However, looking at the end of this ROM, it does start to look like the ROM has gone bad.

When viewing the PAD and PADD at first they look good $0B40 (FF) and $0B41 (00). Although I can not change the data in the PADD. Where I should see PAB and PADB, does not look so good. $0B42 (8F) and $0B43 (FF)

which sets up PORT B as Outputs. I was able to verify this using LEDs. Port B Lights up the LEDs but as PORT A is setup as Inputs. It does not light up the LEDs. Again, this looks like it may have been a customized 6530-002.

I guess I will know more, when I hear back from my friend, and or when I receive the 6532 replacement board.

This is the ROM code I saw starting at $1308 and the differences from my ROM starting at $1F08. I am guessing after $1339 the code seen on the ROM being tested is no longer valid. 

[Jeff M. Nay]

Thank you

 

From: dominic bumbaca [mailto:dominic...@yahoo.com]
Sent: Sunday, August 07, 2022 1:54 PM
To: nove...@gmail.com; KIM-1
Subject: Re: KIM-1 Troubleshooting

 

6532 replacement PCB went out in yesterday's mail.  With luck you will have it Tuesday. 

Sent from Yahoo Mail on Android

 

On Sun, Aug 7, 2022 at 1:24 PM, Jeff Nay

<nove...@gmail.com> wrote:

To view this discussion on the web visit https://groups.google.com/d/msgid/kim-1/a2de60ce-bcbb-4848-8041-cde86d7ca1bbn%40googlegroups.com.

[Jeff Nay]

My friend was able to confirm that there is no other ROMs built into the system, that this KIM-1 came out of. Here are some pics. It looks like it went in for repair, and was never fixed.

You can see Power and Ground at the TOP right Application edge connector and all the port pins running to the add on board.

[Jeff Nay]

Why hasn't anyone considered creating a micro controller replacement for the 6530's? I like the old 89C51 which has 4K programmable ROM, 128 RAM and 4 - 8 pin I/Os and two timers.  Or something similar maybe something a lot smaller,

that does not take up the whole board. Any suggestions?

[Jeff M. Nay]

 

I think I have actually figured out why my breadboard project was not working, when I first tried it. I did not have pull up resistors on RS0 (K4) or CS1 (K2)

 

I just added them, and it did make a big difference.

 

It looks like my PAD and PADD and PBD and PBDD are working, … I can set them up as either input or outputs.

However the ROM portion is still off. Although I did notice a pattern. It looks like it is repeating 8 bytes of good code, there by replacing 8 bytes of good code.

 

It does this all the way throughout the ROM.

 

Now here is a question that just ran through my mind. If I had to replace the 6502 and the 6530-002, because they were both bad.

What is the chance that the 6530-003 is good??? :o(

Although I think I might still be able to boot up, even if it is not working correctly. We will see soon.

 

 

 

 

[Jeff M. Nay]

Here is a reply from Bob Applegate of Corsham. I asked him about using a Arduino Nano or Pico

 

I think the Nano can handle up to 5.5V

 

 

HI Jeff,

 

I did work on emulating a 1793 disk controller using a much faster processor, but maybe an Arduino Mega could do the job of emulating a 6530.  It is only running at 16 MHz… lots of work to do very quickly to keep up with a 1 MHz 6502.

 

Two 8 bit ports can handle all the select, phase 2, /RESET and R/W inputs and two address bits, another 8 bit port having the other 8 address bits, and another bidirectional port for data.

 

It would be tough to get the code to be fast enough as it would need to decode the selects, possibly do a look-up of either ROM or RAM based on the address, present data on reads, etc.

 

Arduinos are 3.3 volt devices?  Might need to buffer the voltages but probably not.

 

Let me know how it works out ;-)

 

Bob

 

 

From: h.o...@hansotten.com [mailto:h.o...@hansotten.com]
Sent: Monday, August 08, 2022 10:52 AM
To: 'Jeff M. Nay'
Subject: RE: KIM-1 Troubleshooting

 

A Raspberry Pi Pico with level translators could do that.

And I have seen a Teensy 4.1 to be a 6502 CPU.

 

So it can be done.

 

A 6532 and a ROM is what the replacement board is about, it works.

 

 

From: Jeff M. Nay <nove...@gmail.com>
Sent: Monday, 8 August 2022 16:11
To: h.o...@hansotten.com
Subject: RE: KIM-1 Troubleshooting

 

Double checked all address lines again. All Good !!!

 

Any microcontroller ideas, to replace either 6530 ???

 

I heard that we have a pretty good programmer in the group…

 

From: h.o...@hansotten.com [mailto:h.o...@hansotten.com]
Sent: Monday, August 08, 2022 9:26 AM
To: 'Jeff M. Nay'
Subject: RE: KIM-1 Troubleshooting

 

The second 6530-003 has the tape ROM, and has the free I/o ports (the ones connected to that rely card).

The KIM-1 will happily boot and function with it if it is not present (like a standard PAL-1 :) )

So remove if that is possible until the KIM-1 is alive again.

 

Sure the address lines are well connected A3? to the breadboard since the 8 byte pattern?

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[Hans Otten]

GitHub - MicroCoreLabs/Projects
Teensy based, fast enough to emulate cpu's like 6502. Well documented. 

[Hans Otten]

5V adapted, small enough to fit a 40 pin IC. 

[Jeff M. Nay]

I am currently simply using a logic probe to look at signals. Is it active (B), Low (L) or High (H) and comparing them to a working KIM-1

 

Since adding the Corsham 6530-002 replacement. I am seeing a much better set of signals going to the U4 (74145) decoder. One display is partially active.

 

I am still receiving  several bad signals coming in and going out of U24 (74145) decoder. So, I replaced it, but still seeing the same bad signals.

Looks like I have a bad input D on pin 12 which is going low – This one concerns me the most, as I believe this input comes from my 6530-002 replacement. Which should be good. I checked pin 21

Of U2 (6530-002) and it is also Low. I am also seeing a low on pin 4 (Output3) and I am seeing a high on pins 6,7 and 9,10,11 (Output 5,6,7,8,9)

 

Looking at U17 (7406) I have one bad signal on pin 10 seems to be stuck low (This seems impossible unless 7406 is bad)

Looking at U13 (74125) one bad signal on pin 5 which is stuck high. I have also noticed the Output pin 12 on U6 (memory) is high – possibly bad memory chip. When I try

to piggy back, I get no display at all and pin 12 is still stuck high.

 

So, right now I am considering replacing U6-2102 Memory and U17-7406 Inverter. Anybody have any suggestions on why I am getting so many bad signals on U24-74145?

 

I went ahead and piggy backed the 7406 and did see a difference in the display. Now instead of a small c showing up, in the left most display. I see a full sized 6. See pics bellow.

However I believe that pin 10 is still being held low, so I am not sure why it made a difference at all.

 

I guess my main concern is why I am not receiving the correct Inputs on U24 74145. A,B,C and D should all be receiving proper inputs from the 6530-002 replacement.

I have of course tried replacing U24 with a new chip, but no change.

 

I will try to get a video created, showing what signals I am seeing, using a logic probe on U24 and at U6. Where I have pulled the suspected bad memory chip.

I will try to display what good signally should look like, using my working KIM-1 and then display what is showing up on the non-working KIM-1 for comparison.

 

I would love to hear any and all inputs. This is a board with multiple failures, so it will not be a simple fix. One thing at a time, I guess…  

 

Looking at the schematics, I might want to start looking at U15 and U16, which controls the R/W and the φ2 and φ2 NOT. I will probably

Have to break out the OScope to take a look at these signals. Unless my probe shows that there is something not working.

 

 

U24 - 74145

U17 - 7406

U13 - 74125

 

       

 

 

 

     

 

 

From: ki...@googlegroups.com [mailto:ki...@googlegroups.com] On Behalf Of Hans Otten
Sent: Wednesday, August 10, 2022 3:06 AM
To: KIM-1
Subject: Re: KIM-1 Troubleshooting

 

5V adapted, small enough to fit a 40 pin IC. 

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[Jeff M. Nay]

I have just finished uploading the video that I created today. Thought you all might like to take a look. It gets real interesting at the very end.

And it definitely points to the memory being the main problem, at this time. So, watch to the very end.

 

https://youtu.be/PG-K_6m9JdE