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convert a 27c series eprom to a 2 wire serial eeprom????

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How dificult would it be to make up some type of conversion board to accept a 2 wire serial eeprom but plug in and take the place of a 27c series eprom. I know the 27c series has a general 8 in 8 out type setup with each let showing one bit in the byte and the serial eeproms work by flashing the line on and off.
How could I set up something like that, where it would take in the 8 seperate address coming from the 27c socket and convert them to something the 2 wire serial can understand. And vice verca.


New Member
parallel Eprom => serial EEprom

Well, it's doable. Whether it's worth the effort to design and build is up to you.

I'm assuming you want to do this in order to take advantage of the much higher memory density of EPROMS vs. serial EEPROMS. Is this correct? Also, do you want to use the EPROM in a read-only capacity or do you want to emulate the complete functionality of a serial EEPROM?

Non-volatile, non-serial memories like EPROMS and SRAMs usually don't have multiplexed address lines like DRAM, and this will increase your device count. I'd suggest using two xx164 SIPO (serial-in, parallel-out) shift registers for the address lines, and a xx165/xx166 PISO shift-register for the data lines if it's a read-only application. For reading and writing, a universal shift-reg like the xx299 is appropriate (You would also need to account for the programming circuitry).

Unless you're trying to use up some parts from your junkbox, take a look at the Atmel dataflash parts. Very cool idea, they take dense flash-EPROM and give it a serial interface. Densities are far higher than you'll find with EEPROMs at any price. 4Mbit and 8Mbit densities are typical.

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