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W65C02 is not Outputting on Address Pins
Posted: Fri Mar 06, 2020 9:37 pm
by PersonHuman250
I'm not sure if this is the right place to put this but I recently bought a W65C02 to build a simple computer I had it working but I took it apart now its not outputting on the address/data pins. I'm not sure if I have bricked it the part was ordered from jameco. Any responses would be helpful. Thank you.
here's the picture(Sorry about my bad wiring):
Re: W65C02 is not Outputting on Address Pins
Posted: Fri Mar 06, 2020 9:50 pm
by GARTHWILSON
A diagram and photos might be helpful. Do go through the 6502 primer at http://wilsonminesco.com/6502primer/ which is about making your own 6502 computer, in 22 logically-arranged sections. Section 19 is on simple debugging steps. Did you get the processor from a legitimate distributor? See our sticky topic, "65xx parts sources, genuine and fake."
Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 12:02 am
by BigDumbDinosaur
I'm not sure if this is the right place to put this but I recently bought a W65C02 to build a simple computer I had it working but I took it apart now its not outputting on the address/data pins. I'm not sure if I have bricked it. Any responses would be helpful. Thank you.
I'll echo Garth's question. From where did you obtain your 65C02? If it was from anyone other than an authorized WDC distributor it's likely you have a counterfeit part.
In any query such as yours always provide a schematic and if possible, any test data that you acquired while trying to troubleshoot. Photos of the unit are also helpful, as they may reveal to the trained eye a construction flaw that is preventing your unit from working. There's no way to determine from your description what the problem may be.
Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 1:21 am
by leepivonka
Do you have the CPUs BE (bus enable) pin tied off appropriately?
Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 11:49 am
by BigEd
Welcome, PersonHuman! I'm sure we can resolve your puzzle, given enough information.
Please respond with replies- people may easily miss edits to earlier posts.
Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 12:09 pm
by cjs
Clicking your photo link gives me, "The requested URL was not found on this server. That’s all we know."
It's better to upload images here rather than link to off-site images. This both avoids them vanishing later on should they be taken down on the other site and also shows them below the message. (You can also display attachments inline in the message.) When editing your message, look below the Preview/Submit/etc. buttons and you'll see an "Upload attachment" section allowing you to attach an image (or other) file. (You'll first have to download it from Google if you don't already have a local copy on your machine.)
You do mention that you "took it apart," and I'm presuming it wasn't working after you put it back together again. Walk through your conections very carefully; it's easy to get one wrong or forget one. (This happened to me just the other day when I put back together a breadboarded project I'd taken apart; I'd forgotten that my PIA needed the system clock input as well.)
Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 3:30 pm
by PersonHuman250
Bus enable and clock in are all hooked up properly and the part was bought from a legit seller. I'd be happy to answer any more questions.
Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 3:59 pm
by Dr Jefyll
Bus enable and clock in are all hooked up properly and the part was bought from a legit seller. I'd be happy to answer any more questions.
Hello, and welcome. Just thought I'd mention... being willing to answer questions is OK, but what's better is to make an effort to
volunteer as much info as possible. And do your best to
be specific. (Thanks, btw, for adding the photo attachment -- that's helpful.

)
"Hooked up properly" is rather vague, unfortunately. We don't know what you think is proper. Also, what exactly do you mean by, "not outputting on the address/data pins" ? Are they high? Low? Floating? Also, you seem to have no connections to the data bus pins. Under those conditions I'm at a loss to know what you expect!
Please make an effort to talk to us and provide as much info as possible. This'll make it immensely easier to help.
Have fun and keep us posted,
Jeff
Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 4:12 pm
by PersonHuman250
By not outputting I mean not outputting any signal high or low and by hooked up properly I meant hooked either to positive or negative depending on the pin.
Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 4:18 pm
by Dr Jefyll
By not outputting I mean not outputting any signal high or low and by hooked up properly I meant hooked either to positive or negative depending on the pin.
Best if you slow down, read my previous post again, and think about what I'm saying. For example, "depending on the pin" is not specific. A specific answer would tell us, for each pin in question, whether it is high or low.
Understand that we need details. They matter!

Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 4:28 pm
by PersonHuman250
Ill list off whats connected to what. If its not on here its not hooked up.
ready: positive
interrupt request : positive
non mask-able interrupt: positive
VDD: positive
VSS: negative
bus enable: positive
Phase 2 in clock: crystal oscillator high output
set overflow: positive
reset: connected by 1k resistor to positive with wire connected to button connected to negative
Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 4:47 pm
by Dr Jefyll
In the photo, the signal from the oscillator appears to connect to pin 4 of the CPU (not pin 37). Is it possible you're counting the pins clockwise, rather than counterclockwise as you should (when viewing from the top)?
Also, I don't see any bypass capacitors on the board, and that's a no-no. Garth's primer (linked to in his post upthread) is a good place to learn about basic stuff like that. (edit)
cheers,
Jeff
Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 5:52 pm
by GARTHWILSON
It looks like you're numbering the pins wrong. This is a top view:

- DIPpinNumbering.gif (11.04 KiB) Viewed 1988 times
Since this is the second one of these we've had in five weeks here on the forum, I'll add it to the 6502 primer.
Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 6:47 pm
by Dr Jefyll
[...] this is the second one of these we've had in five weeks here on the forum
Right, and I also recall some other WTH moments mentioned on this forum recently.
We've
all payed our dues in the Headslap Club!

Re: W65C02 is not Outputting on Address Pins
Posted: Sat Mar 07, 2020 7:27 pm
by BillO
In the photo, the signal from the oscillator appears to connect to pin 4 of the CPU (not pin 37). Is it possible you're counting the pins clockwise, rather than counterclockwise as you should (when viewing from the top)?
Almost certainly. Even if he had the chip around backwards it would be pin 24.
I wonder what the effect of putting power between reset and A4 would be?