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Thank you for the detailed response :) I will double check my reset line circuitry. I also took the PCF8584 out of circuit and only hooked up VDD & VSS and then connected the RESET pin to VDD using a 4.7k pull up resistor, and still had the RESET pin registering as low. I'm going to order a new ...

Thanks for that additional information. I've been working on this project the last month or so, and updated my schematic to reflect the changes you mentioned. Removed /INT Added a resistor when setting pin 12 high as part of the address decoding Added a 12 mhz Clock I also got the MADS assembler run...

Yup, I used KiCAD and then used Photoshop to add some notes to it. I'm using the same CLK for the 6502 and PCF currently. I don't need to send very much data via the PCF so I thought it should be fine, at least for testing. Would I be able to use another CLK source if i wanted it to be faster? Haha,...

Thanks for clarifying my questions about the 6502 code :) I'm hoping this weekend I can make some more progress on it. Sorry for the messy photo. Last night I created a schematic for it. Currently I have it wired directly to the 6502 and have it accessible on addresses 6000 - 7FFF. I believe this sh...

Hello, I've gotten my PCF chip all wired up and I've been testing with the assembly code you've included; however I've ran into a couple of problems. 1) I wanted to clarify what assembler you're using for this code? I'm guessing it's Mad-Assembler (MADS), but I'd like to confirm :D 2) In the "p...

Sounds great. Thanks for the additional information. I plan on using a 6522 for it. I got it wired up, and am getting ready to power it up to begin testing it

I will let you know how it goes!

Hi, I just wanted to say this is a really cool project, and you've implemented it beautifully. I'm working on a similar project right now, using a 6502 computer to talk to a PCF8584P and found your 6502 code very helpful for how to initialize the chip. I saw that you're assigning address $55 to the ...