EEPROM sizes ...

[sonder]

http://www.jameco.com/webapp/wcs/stores ... 1_74827_-1
http://www.jameco.com/webapp/wcs/stores ... 4Aod8HUAfQ

So, my partner is asking me to buy these for our dev carts, and he claims that these chips are 256KB and 64KB respectively (8 and 4 times what need for the current project), but the literature lists them vaguely as 256K and 64K which to me, seems like it could mean kilobytes OR kiloBITS, and also saying for example on the smaller one that it's "8192 words by 8-bit", saying nothing about pages or specifically listing the number of bytes. I believe they are actually 32kbytes and 8kbytes respectively, though my partner insists it's 8 times more.

Anyway, the point of this is I wanted to buy chips larger than what we immediately need so they could be potentially reused for a future UxRom project. So can anyone shed some light on this? Or tell me if you think that's a bad direction since I have only cursory knowledge about mappers etc and I don't know if it's counter productive, I'm just thrifty.

[thefox]

I believe they are actually 32kbytes and 8kbytes respectively, though my partner insists it's 8 times more.

You're right and your partner is wrong.

EDIT: One way to verify this is to look at the number of address pins, e.g. the 32KByte ROM has 15 address pins (A0..A14), so it can address up to 2^15 = 32768 bytes of memory.

[qbradq]

If your partner is starting EE, they need to understand that "K" means nothing. Got to read the data sheet. 8192 8-bit words means 8 KBytes.

Also, I'd recommend buying more chips than you need. Those things are easy to fry, especially if you've never done that type of work before.

[mham]

I'm sonder's partner in this project. I just didn't explain this properly so there was some miscommunication on my part . The eeprom can hold 32768 bytes. 32768 / 1024 = 32K. The chip is 256k with a wordsize of 8 bits.

Also, I've got plenty of experience working with memory. I am interested in low level computing, have built a few 8 bit computers, hand programmed all of them. I would disagree that eeproms fry easily. If you are aware of all the voltages you'll be fine. I would say that eproms that require larger voltages to program (such as 25v eproms) are more prone to frying due to the simple fact that there is that large voltage that is now in the mix and if applied to the wrong pin you'll fry the chip. eeproms that are 5v across the board won't fry from accidentally applying 5v to one of the pins.