Ralphy Rocket Posted May 5, 2015 Share Posted May 5, 2015 Hi Friends! I want to make cartridge to store only 16k cart roms..no fancy bank switching just some dip switches to select..my question, what is the easiest eeprom family to use on my 8 bit...I've used 12v programming in the past but.I rather use 5v only for a simple project like this....what speed? Quote Link to comment Share on other sites More sharing options...
Joey Z Posted May 5, 2015 Share Posted May 5, 2015 pretty much anything 8 bit wide will work, I don't think you could find ROMs too slow in this day and age. Keep in mind that 16K cartridges on the 8 bit computers were supposed to be two separate ROMs, so there are a couple ROM select signals that you have to OR together to make the overall select signal, and then one of them becomes your high order address bit. Quote Link to comment Share on other sites More sharing options...
Ralphy Rocket Posted May 6, 2015 Author Share Posted May 6, 2015 Thanks for the response Joey Z! Yes the logic to "chip select" I can cobble together. I need to know What brand, speed, that behaves well in the circuit. It's just for having some fun, nothing serious. Just messing with my 1200xl...any thoughts? Ralph Quote Link to comment Share on other sites More sharing options...
Joey Z Posted May 6, 2015 Share Posted May 6, 2015 (edited) Thanks for the response Joey Z! Yes the logic to "chip select" I can cobble together. I need to know What brand, speed, that behaves well in the circuit. It's just for having some fun, nothing serious. Just messing with my 1200xl...any thoughts? Ralph like I said, pretty much any 8 bit wide ROM should work OK. look for 49xxxx series for flash, 27xxx series for UV EPROM. There are others, but I don't know them as well off the top of my head. EDIT: and if you're really bent on finding the right speed, 1/1.79mhz gives you a period of 560 ns. I think the slowest ROM I've ever seen was significantly less than this at an access time of 150ns, so pretty much ANYTHING you can find will be fast enough, unless you find something really old. Edited May 6, 2015 by Joey Z Quote Link to comment Share on other sites More sharing options...
Ralphy Rocket Posted May 7, 2015 Author Share Posted May 7, 2015 Thanks! I've never "done the math". The design discipline has always escaped me! :-) I usually wire it up and turn it on! Hope it works. Yes...560ns anything would work. if I understand correctly 6502 access memory in half a cycle? So anything faster than 280ns ...still anything would work. I'm going to look in the digi-key catalog for a flash eepron. Thanks! Quote Link to comment Share on other sites More sharing options...
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