> Electrically, the programming pins are similar. You will find that to > program a "C" based part, the current required to be sourced to the "Vpp" > (_MCLR) pin is on the order of 40 mA. For an "F" based part, the current > required to be sourced to the Vpp pin is less than 1 mA. Electrically, it > is not an issue to program an "F" based part with a programmer that is > capable of programming a "C", but the reverse is not always true. > > If you do not have an option for programming the "F" based parts, then you > should find the vendor of the programmer and see if they have a software > upgrade for programming the parts that you want. > > Good luck, > > myke Myke, It so happens that my friend and I are trying to use the programmer supplied with your book to program the 16F74. From what I understand, it has a different algorithm for erasing (as opposed to 16C74). Since our chip is not listed under El Cheapo's drop down menu, my friend wrote a console-based driver of his own. After about three evenings, I got it to work on my programmer by adding a 47nF capacitor at 78L12's GND and OUT pins. The bad news is, that didn't solve the problem for him - after erasing, the last word is still 0x0, not 0x3FF as it should be, and the chip is therefore not being programmed. Other chips are programmed just fine. There must be a good reason why you didn't include the 16F7X series in the list of supported devices. Other than the differences you listed above, are there any others that affect El Cheapo's ability to program our chip? Thank you for your help! Vitaliy -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu