IS YOU IS, OR IS YOU ISN'T

THE MAGAZINE FOR COMPUTER APPLICATIONS Circuit Cellar Online offers articles illustrating creative solutions and unique applications through complete projects, practical tutorials, and useful design techniques.

	IS YOU IS, OR IS YOU ISN'T?
by Tom Cantrell Start ı Earth To Tom ı Name Gameı The Good Old Days ı Flash Forward ı Sources and PDF Earth To Tom OK, where was I? Oh yeah, so I was reading an article in a recent issue of Circuit Cellar and enjoying it thoroughly as usual, when I started seeing references to a "serial EPROM" on the board. I was pretty sure that was supposed to be "serial EEPROM," but as usual, couldnıt avoid the obsession to nail it down. It would have been easier if there were no such thing as serial EPROMs, but they do in fact exist. Serial EPROMs mainly occupy a niche as boot-up chips for FPGAs and are quickly being replaced with newer nonvolatile technologies, but I couldnıt rule it out. There was a part number, but my PC wasnıt on at the time to check it over the Internet. Scanning forward, I hoped to find reference to in-system updates or such that would imply EEPROM rather than EPROM, but those functions werenıt intrinsic to the design in the article. Finally, I peered at the schematic (thank goodness Circuit Cellar always provides real schematics) and noticed the signals connected to the chip were labeled EECS, EEDATA, and so on. My feeling of Sherlock satisfaction was short-lived as I started sizzling and dialed headquarters. I suspect Steve just holds the phone away from his ear while I rant. Then, after he canıt hear the squawking from 3ı away, he gets back on and says something like "so what can I do for you." In this case, he actually recognized off the top of his head the part number as an EEPROM and promised to investigate how the mistake percolated into print. But, thatıs just the start of this semantic saga. A few days later, I got a call complementing me on one of my articles from the supplier of the gadget involved. As we chatted about it, I asked if heıd noticed any mistakes, and he replied there was only a minor one. Although I described in my article their built-in serial EEPROM, he said they were actually using a serial flash memory chip. Now, I feel really bad when I make a mistake, however, I will accept notification of such gracefully. But in this case, I was having trouble. Did I make a mistake or didnıt I? Usually itıs pretty clear one way or the other, but not this time. Is it a flash memory chip or is it an EEPROM? PREVIOUS • NEXT Circuit Cellar provides up-to-date information for engineers. Visit www.circuitcellar.com for more information and additional articles. For subscription information, call (860) 875-2199, subscribe@circuitcellar.com or subscribe online. ıCircuit Cellar, the Magazine for Computer Applications. Posted with permission.