8085 Project !!

Hi All;

Chuck, Thank You for Your reply and Suggestion, I will Implement that and let You know the Outcome..

I have implemented it, the 74ALS245 doesn't get hot now, But, I can't say it was this wiring change that did it..

I still doesn't work, so the circuitry will need further looking into, and a check of more of the IC's needs to be made..

THANK YOU Marty

Hi All;

I am trying something slightly different, I was looking for something simple for testing Ic's, and in my search, I ran across testing a Z-80, so I typed in Testing an 8085, in Youtube and I found a simple circuit for doing that, which I am attempting to implement on Breadboard..
Then I will try and do the basic same circuit on my WireWrap Board, taking out ROM and RAM.. And seeing if it will pass that way as well..

OK, It works on the BreadBoard, now to work on seeing how much I can slow down the clock, and possibly then Single Stepping..

I am using a 1.84 Mhz Resonate Oscillator divided by seven or eight, and the 8085 still Runs..
So, next I am going to try it on the WireWrap Board, and see if I can get the same results..



THANK YOU Marty

Hi All;

I have now tried to run the WireWrap Board, and their is a Problem, So first check connections and then Replace the 8212 with a 74LS373 to make it like the BreadBoard circuit..

It still Doesn't work, even with the 74LS373 wired in..

THANK YOU Marty

Hi All;

Well, I have it running at a very slow rate, it's clocking at 56.25 HZ, I will next week try to get it even a little slower, so I can watch it as it goes thru the program watching it and comparing it to the printed code..

And then, I will make the necessary changes to the RAM select and see if that helps..

THANK YOU Marty

Must be one of the first microprocessors clocked by (well almost) mains frequency :D

But can't you take it a step (no pun intended) further and make it do single steps, that way you can check all signals while they remain static?

BTW, I love these kind of projects, I found a 20x30 cm 'veroboard' like PCB on a HAM fest yesterday, its got plated through holes so I can even use SMD parts soldered on top and connected on the other side. I already had some smaller PCB's like these but never saw such big ones. Maybe I will setup a similar project based on some exotic CPU.

Hi All;

GertK, thank You for Your reply..

Yes, I do plan on Single Stepping it, I have been thinking about it and the Circuit, and I will try and implement my changes on the BreadBoard, it has not worked so far, Could be for Many Reasons..
Hopefully, next week..

THANK YOU Marty

Not all microprocessors are super reliable at very low clock speed, I think. Single stepping at higher freq. is a much more stable solution.

Hi All;

Thank You, Christoffer for Your response..

I will be working on the single Stepping next week, I just thought it was Interesting that it worked at all..
Mainly I wanted to see whether I was reading the Eprom at the correct address location..

THANK YOU Marty

Hi All;

Well, I found some of my Problem, I have all of my HP Led Display, wired Backwards, so when I wire it for a 1, it displays an E..
So, all of the Displays will need to be re-wired..
I will do one and make sure, I have it correct in my mind..
On the Display the schematic showed I0, I1, I2, I4, and so I wired as such, but I guess that was not correct..
I had I0 to bit 0, but it seems to be it needs to go to I4, and such..
I have switched the input to the HP Led's and tested the first one before I did the rest of them.. And it Tested to be correct..
Now I need to work on the Single Stepping Problem..

I have the Single Stepping working as much as I know how to do for Now.. It does not completely work, it skips a few beats..
So, for now I will put it away, and think on it, behind the Scenes..

THANK YOU Marty