Hello. I'm cloning a w65c265sxb board, but making it to run at 4.9152 Mhz and 3.3v.

I just wired the memory, following WDC's schematics, using the same components and values.

I wired the memory as in the schematics, but when I modify one single memory location, and then read it again, I get that not only that single memory location has changed, but all the following ones.

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Example:

I use the D command to display memory contents between 0200 and 02FF. It replies 9C 9C 9C ... 9C.
Then, I use the F command to fill that memory locations (0200-02FF) with 00.
Then, I use the D command again to display memory contents between 0200 and 02FF. It replies 00 00 00 ... 00.
Then, I use the M command to change the memory contents, starting from 0200. And I put E0 in that single memory location (0200).
Then, I use the D command again to display memory contents between 0200 and 02FF.

The expected reply should be: E0 00 00 00 ... 00.

But the reply I get is E0 E0 E0 E0 ... E0.
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What I've tried running it @5v, with no success. I checked all the wiring, and it seems OK. The memory module I'm using is AS6C1008-55PCN of 128K, but with A15 and A16 wired to GND, so I can use only 32K of memory.


I'd appreciate some tips or help on this.

Thanks.

It smells to me as through A0-7 are stuck on some constant value, as seen by the SRAM. Possibly also other address lines.

I've checked all the address and data bus lines between the '265, the 74hc00 and the AS6c1008. Evertyhing ok.

Should I provide the board with a stronger 3.3V supply, instead of that of the FTDI232???

As Chromatix said, it seems that A0-7 are stuck on some constant value. I'm no '265 expert, but I know the pins which act as address outputs can also be configured as parallel IO. Maybe this explains what you're seeing. In other words, it seems possible the chip is not configured properly (for what you're doing).

-- Jeff

_________________
In 1988 my 65C02 got six new registers and 44 new full-speed instructions!
https://laughtonelectronics.com/Arcana/ ... mmary.html

I emailed Alliance Memory about this and they confirmed that CE2 should be tied to Vcc all the time in the AS6C1008.

I also grounded A15 and A16.

So now it works!!! I can use Bitwise w65c265 hacker!!!

Next step: wiring the EEPROM.