| ??? 10/24/07 12:39 Read: times |
#146131 - FLASH ROM and EEPROM Responding to: ???'s previous message |
Neil Kurzman said:
If I remember, a factory has to make a special ROM chip for you that contains your code. This code can never be changed. This has not been true for many years. A flash based micro can hold you loader code, and still execute code from RAM that is wired in code space. I was talking about the ROM in the old days. I wasn't even thinking about flash rom when I wrote my previous reply. otherwise I would state "Flash Rom". The thing in common between EEPROMS and FLASH ROM is that they can be reprogrammed many times. The technology in them is different, and the way you set up the data when programming them is different. I favor parallel EEPROMS (Like the 28C256 variety) for small projects because all you need to do in order to write data is to set your data, the address to write it to, and lower the WE and then raise it after say 100ms (depending on the datasheet). If I remember, with a flash, you had to write a special sequence of code, and you can only write chunks of data into FLASH ROM where as in an EEPROM, you can write only one byte of data at any address if you wanted to. |
