I am trying to build simple system with UA6527 (clone of Ricoh 2A03, which was used in Famicom/NES clones). Basically it is a 6502 with different pin arrangement and some additional I/O pins. I tried to test it by forcing constant execution of NOP instruction, by pulling up/down D0.. D7 lines with 3.3k resistors. Signals on lines from A0 to A13 are fine. But last two address lines behave in weird way - logic analyzer shows the same pulse on each one of them and duty cycle is NOT 50%.
There is no short circuit and I tested three different CPU s from two different suppliers.

Any ideas?

The 2A03 has some built-in devices which live at relatively high addresses. It would be reasonable for the CPU to execute something other than what was on the data bus when reading from those devices.

So, does it mean everything is perfectly normal? Signals on A14 and A15 should look like that?
If so, I'd like to proceed with the next test, run some code from an EPROM and change state of one of the built-in outputs.
Then I'll try to use video controller: UA6538.

I also have few other question regarding schematic I use as a reference.
1) Why there is a filter on U1 (SRAM) CS line? It will cause significant delay in chip activation. C20 will be discharged slowly by R14, so the stope of the signal won't be steep. After deselecting CD line capacitor will be quickly charged again through D1. What is the reason of that? I always thought SRAM should be selected right away after setting its address on address lines...
2) Why there are C21 and C23 capacitors on DBE line of video chip?
3) How to test my device by toggling one ox the OUTx lines?

I just got a batch with the 6527 in it as well..

DIP-40 IC's galore! You get what you pay for! 8088s 6502s 6532 RIOTS #Shorts
https://youtu.be/RyR7n50a7YM

Did anyone succeed getting a 6527 operational?

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New new new new new video out! Serial Bootloader for my 65uino
Also, check out: I2C on a 6502 Single Board Computer
and Complete hardware overview of my 6502 SBC R1