172 DEAR HACKER

172 DEAR HACKER

What about apartment buildings that have a unique ZIP+4? Will they have the last two digits of the street number appended, or the apartment number, or neither?

If you are as intrigued by these questions as I am, I look forward to your follow-up article.

LM Berkeley, CA

The Face Identification Marker (FIM) determines whether or not a letter is processed by a BCS. If FIM A or FIM C is present, then the letter will go to a BCS regardless of where POSTNET is located. In fact, as long as the appropriate FIM is present, the letter will go to a BCS even if POSTNET is not used at all.

Our understanding of MLOCR is that it uses various elements of the address block to determine what barcode should be sprayed. The MLOCR will always try to spray the most accurate address information. For instance, if a letter has a regular ZIP, but the MLOCR determines the location’s ZIP+4, then it will spray the more accu- rate barcode instead.

As far as we know, there is no advantage to using “wide-area” barcoding. It is an example of USPS actually responding to the needs of businesses, many of which use window envelopes for expedience. Wide-area barcoding simply makes it eas- ier for those businesses to make the transition to POSTNET.

Eventually, MLOCRs will be upgraded to use ZIP+6. As a small business, 2600 awaits this increased complexity and confusion with delightful anticipation. In any case, your suggestion of a follow-up article will be mailed to those responsible.

Dear 2600: Ever since the California DMV decided it would be a good idea to

slap a magnetic strip on the back of their driver’s licenses, I’ve been itching to get into mag strip hacking. Of course, mag strips have been around for some time on the backs of our credit cards, ATM cards, and student ID cards, among others. But now there is an additional motivation. A driver’s license is a whole new ball game.

From what I’ve heard from other mag strip hackers, the data encod-

ed on the California driver’s license is basically the same as the info

TECHNOLOGY

printed on the card. Not too exciting. But the media is saying that in the future the DMV wants to encode your driving record on the card. Now that would be something worth modifying.

Imagine getting pulled over on Sunset Boulevard. The cop asks for your license, looks you over, and goes back to the car. While you sit there confidently, the cop zaps your card through his portable mag strip computer. No violations show on your record. Of course, the cop gives you a speeding ticket, so he encodes it straight onto your card and gives you a paper copy as well. But once the cop pulls away, you whip out your laptop computer and homebrew mag strip reader/writer from the back seat. A few strokes on the keyboard and your driving record is clean again—at least on your magnetic strip.

But even while there is no driving record on the card as of yet, it would still be useful to modify the info on the mag strip. Say sometime in the future you attend a large political protest, and you are arrested along with hundreds of others. In order to process this volume of people, the cops are using mag strip reader ticket printers. They zap your card, enter the violation, time, date, etc., and it prints out a citation for you. Of course, the cops aren’t paying enough attention to notice that the information on your magnetic strip is different from the information printed on your license.

That was mostly fiction. Now here’s some fact. In order to get in on the ground floor of the mag strip scene, I purchased a used mag strip reader from Marlin P. Jones and Associates of Lake Park, FL. The model was the Taltek 727. Cost only eight bucks. I figured out how to power the device, and by gosh it worked!

The unit is powered by a 12V AC supply. It has a RAM, ROM, a tele- com microprocessor, and a 16-character alphanumeric display. Two phone jacks are on the back as well as some sort of serial I/O jack. It has two keypads. One has standard DTMF style keys and the other has keys for specific functions. The unit has several functions and was apparently used by a gas station of some sort. The most useful function by far is its ability to read the numeric track of a magnetic strip and display this info on its screen.

To do this, turn the unit on and get the “swipe card” prompt by hit- ting the “check” key, for instance. Then hit the # key. Now swipe the