Hello. Is this a 6502?

[kasrym]

Greetings,
I am wanting to build a small setup, but I am needing to confirm if this 6502 is legit. Thanks!

[GARTHWILSON]

Yep, a Synertek SYP6502 made in the 33rd week of 1980.

[kasrym]

Woot. Thanks for the quick response. I am trying to get it up and running, but for the project all I am getting is the lights to be solid. I dont know if its my oscillator. If I pull the power off my 7404 I get no change.

The project I am doing is http://www.reocities.com/SiliconValley/ ... 02prj1.htm

[GARTHWILSON]

Be sure to check out my 6502 primer at http://wilsonminesco.com/6502primer/index.html. It has 22 sections addressing many aspects of building the computer (including the clock and troubleshooting, both of which you mention) and related things.

After a very quick look at your page, I might comment that the 65c02 is in production today, in huge volumes (hundreds of millions of units per year, mostly hiding as the processor core inside custom ICs for automotive, industrial, appliance, toy, and even life-support applications), and the fastest of them are running at over 200MHz. The company that licenses the IP is the Western Design Center. Their 65c02 has a lot of hardware and software benefits over the old NMOS 6502 and even over previous 65c02's from other manufacturers, including the ability to stop it in either phase without losing the content of its registers (since you mention that on your page). The natural upgrade path is the 65816.

It looks like you have a lot of good articles I should look into, linked on your home page.

[kasrym]

I will definitely go through your primer. And credit is due for the page its not mine. I actually found it off this site.

[BigEd]

Hi kasrym, welcome!

kasrym wrote:

The project I am doing is http://www.reocities.com/SiliconValley/ ... 02prj1.htm

The with-photos version of Adam's "First Great 6502 Project" can be seen at
http://web.archive.org/web/200910210405 ... rj1pic.htm

What kind of equipment do you have? The first things which are relatively affordable and very useful are
- a multimeter (preferably with frequency counter) (nice to have a beeper for short test)
- a logic probe

But even without those, you may be able to rig up some LEDs and dividers to get an idea of which signals are changing and how fast. The first signal to check is the clock, and then the SYNC pin, and then the high and the low address pins, and then the chip select inputs on any RAM, ROM, or IO chips you have.

Oh, and you should also be checking all close signals for shorts! (Including the power rails - all the power pins should be connected to each other, all the ground pins connected to each other, and the power and ground should not be connected!)

Cheers
Ed

(Edit: I had RDY instead of SYNC. Some inputs should be tied off, and you need to check that they are.)

[kasrym]

Thanks for the link Ed. Wouldn't the ready pin show a 1 since it's tied high?

[BigEd]

kasrym wrote:

Thanks for the link Ed. Wouldn't the ready pin show a 1 since it's tied high?

Oops - my mistake! I meant SYNC. Let me edit that.

Cheers
Ed

[kasrym]

Ok. So to try to get this up and running, I am setting it for the NOP code. It comes on, the lights toed to the address bus are randomized and then it cuts off. Same result when I remove the clock. Any ideas?

[GARTHWILSON]

Do you have resistors in series with the LEDs? Without them, the processor and other things on the buses won't be able to pull up high enough for a valid "1," because a red LED is kind of like a 1.7V zener diode. Put about a 1K resistor in series. Also follow the troubleshooting process on that page of the 6502 primer, at http://wilsonminesco.com/6502primer/debug.html . Do you have a clean reset signal? Valid clock signal, at the expected frequency? Are address and data lines toggling, and going high enough and low enough to be valid 1's and 0's? What's the power supply voltage at the power and ground pins of each IC? How's the power supply current? Is IRQ\ or NMI\ going down unexpectedly?

[kasrym]

I have a 330ohm in series with the led. And 3.17k for NMI and IRQ. With a logic circuit I built on the top of the board I am not getting a clean high or low on 4 and 6. My clock signal should be clean, but I wont jave access to a scope until Dec 8th. Its clocked at 2MHz with a 7404 and a 1.8 across 1 and 2, 3 and 4, with the crystal going across 1 and 4. I have a 330k going from pin 1 to ground. For my reser I have a 2.7k on 40 to vcc, and a line going to my trigger, with a 10microF cap to ground, and othe side of the switch to ground.

I removed all the leds and just put on off A15. And not getting anything.

My power is 4AAAs going through a 7805.

[GARTHWILSON]

It does sound primarily like a clock problem. The reset circuit, not being debounced, is not adequate, but is probably not what's keeping it from toggling the address lines. The 7805 takes about 1.5V minimum, so if you're starting with 6V from the batteries if they're pretty new, you'll only get 4.5V out of the 7805, which is below spec. for the processor but probably not low enough to keep address lines from toggling.

[kasrym]

Here's my clock as of now.

[kasrym]

Is 2MHz too high since my chip is non-suffixed?

[GARTHWILSON]

If it had an "A" on the end, it would mean it passed the tests to be sold as 2MHz. Since it does not have any letters after its name , it means it did not pass for 2MHz or more. Might it run at all at 2MHz? Maybe, if the other parts are fast enough, meaning it would need help from the supporting parts being able to run on decreased timing margins; but you're also running it below the specified power supply voltage of 4.75V-5.25V, one of whose effects will be to further slow it down.