@KC9UDX : Actually my project was not just for me and I sold some of them to people interested since there was some interest in it. Personally I would change the power supply but it would not be practical for lots of people interested. I'm sure I would hunt down a proper arrangement with tristate ...

The main problem with this method is : Feeding the databus is very time sensitive so if you wanted to do other things beside booting things gets complex. Also, when you add the ram you'd need a way to orchestrate the bus since 6502 will be the outputting side on the bus (or ram, on read accesses ...

By the way, searching the web I saw overdriving the databus is used safely as a hack to increase the TIA's resolution.
http://atariage.com/forums/topic/183085-bus-stuffing-like-the-graduate/

It's still safe for one side (6507) though I don't know if STM32 would like it.

@hoglet : Thanks for the ...

The quick and dirty solution to the startup problem would be to use some kind of startup rom or similar thing that keeps the cpu in a predefined state. Even a controllable free running mode would do. (tieing the databus to EA)

@richardc64 : Actually I was talking about the hardware part, of course there is no reset functionality provided to the end user on c64.

I examined the 2600 circuit again. It seems I misinterpreted the reset part. Pin pulled high with a resistor, also it's tied to GND with a capacitor. This setup ...

Of course original hardware should be examined but another question arises about bankswitching. Is it happening at the same cycle with the read access to the determined address?

Say a LDA $1FF8 switches banks... do A register contain the rom value at $1FF8 at the end of the operation or is it just ...

I was busy with my c64 cartridge project IRQHack64 lately so I haven't got the chance to contribute to the forum.

I started fresh with a new cartridge project for Atari 2600. I intend to create a cartridge that plays games from a sd card. I'm using a STM32 arm chip.

This is just an introduction ...

I've seen V9958 while I was looking for TMS9918 by the way. It needs a little bit more effort in the software department and it's a bit expensive too. Expensiveness doesn't matter that much but at this point I want a simple chip to integrate. Maybe in my next project I could use it.

ps: Just ...

I completely forgot the refresh issue.

@cbscpe : The idea is to drive the multiplexed A0..A6 by VDC which would handle the dram refresh. And drive the A7 by extra logic which would eventually be controlled by a register which is driven by the main cpu. Then one would need to refresh unbanked dram ...

I was into other things so I put this project aside for a while. 4164 dram chips I ordered recently arrived and I'll revisit this project. With the lousy interfacing I was not able to properly build the sram interface. Maybe it was the software that was problematic but now I want to try it again ...

@Martin A : Mine look a lot similar to the below picture.
One of them has Taiwan G2, and an empty dot.
One of them has Taiwan D3, and an empty dot.
Two of them have PHILIPPINES and BR
One has TAIWAN (very hard to read) and A2

All of them have non uniform bottom paint giving the impression that ...

in the below link they are wholesaling a part with Winsome brand :) That's just a typo by the Alibaba web site. The markings on the chip say Winbond, right?


Actually the company's name in that link is Winsome. There is no picture of the IC they sell but the part number is W65C816.


Not sure ...

I've replaced 10k resistors with 1.5K ones (I really don't have 3.3k ones)
I have 24Mhz and 32Mhz oscillators. Divided these by a counter to test 6, 8 and 12 Mhz. 6 and 8 ok, 12 Mhz fails. But my 24mhz logic analyzer can't properly display 12mhz clock too at that frequency.

If this is a ...

Genuine W65C02S and W65C816S MPUs are only sold through distributors authorized by Western Design Center. Going to anyone else almost guarantees that you will be sold "dodgy" parts. Incidentally, you paid over twice as much for those devices as they cost at authorized distributors.

As I said ...

Well, one thing I forgot was indeed BE line. I pulled it up to VDD. The other problem was with me actually not in the setup. The circuit was expected to free run actually. My badness I thought I should have seen EA on the A7..A0 :)

Now I tested one of the chips today and it indeed free runs... I ...