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Welcome! Some low-voltage parts are tolerant of higher voltages, but some aren't - I think I'd say that most aren't. The thing to do is to read the datasheet of the part you have in mind. It's a useful skill anyway, to read a datasheet. Somewhere you're likely to see 'absolute maximum voltages' for inputs, which is usually half a volt higher than the power supply.

So, with very careful component selection, you can make a mixed-supply design. (If this is your first design, or your first build, I'd recommend you leave as much difficult stuff out until the thing is working.)

If you can't find components which can do this for you, you can instead add some specific level-shifting components in between the 3V and the 5V parts of your design. Have a search in the forum - several such components have been mentioned in previous threads.

(And do feel free to contribute to an existing thread, even if it's very old - so long as you're on-topic, that's fine here.)

Right. The additional delay would diminish or even outweigh the benefit of running the CPU at 5 volts. IMO your best option (if you're determined to use that particular RAM) is to just run the CPU at the lower voltage, too.

Despite using a 3.3V supply, one forum member reports running an '816 at 24 MHz. Of course YMMV. Depending on address decoding and so on, other designs may have a lower ceiling.

-- Jeff

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

letuandk, the CY7C1069AV33-10ZXC is apparently obsolete. I wouldn't doubt if there's a replacement that most users would consider to be exactly the same thing; but I haven't searched. I sell a 4Mx8 10n 5V SRAM module which is much more hobbyist-friendly, assembled and tested, for not much more than the price of the part you were looking at. I uses eight Cypress 512Kx8 5V 10ns SRAM ICs in SOJ-36, four on each side of the board.

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http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?