James Musselman wrote: > does this price > comparison include the price of the external eprom and latch necessary > to run the XA???? (and the additional latch to replace lost i/o pins? > and the cost of > the additiona PCB real estate for the extra chips??) No, James, that's not what I had in mind. But since you can't hang external memory off most of the PICs, there's little point in making the point. The consensus was that the PIC series was unsuitable for the application; I was suggesting a chip that is, and my price comparison with the PIC was simply to illustrate that it is a cheap chip; but since you asked the question, let's look at the pricing: - Philips have quoted the XA romless part as low as US$7, but I believe that's a quantity price. So we'll just work on what we pay here, and I've no doubt they'd be cheaper in the US. I've allowed one latch for the multiplexed address bus, and two more to replace lost I/O. Philips P51XAG30 US$11.70 (== AUS$15.50) 27C64 EPROM (28DIP) 2.50 74HC373 latch x 3 1.50 Extra board space (if any) 2.00 Total: US$17.70 Compare this with Digikey's current price of US$21 for an erasable 17C42 - it looks pretty good, actually! If we were to compare with PIC pricing in Australia, it would look even better! Board space is not a major issue; the 40 pin DIP C42 takes up nearly as much room as the PLCC XA and a 28 pin ROM anyway - the latch fits underneath the ROM so it does not occupy any extra space at all. The end result is a much faster chip, with more ROM and more RAM, two serial ports instead of one, and the capability to expand the memory at little extra cost. None of this means that one chip is better than the other; the PIC still has some advantages (low current drain, for example). It's horses for courses. Clyde -- Clyde Smith-Stubbs | HI-TECH Software, | Voice: +61 7 3300 5011 clyde@hitech.com.au | P.O. Box 103, Alderley, | Fax: +61 7 3300 5246 http://www.hitech.com.au | QLD, 4051, AUSTRALIA. | BBS: +61 7 3300 5235 --------------------------------------------------------------------------- For info on the World's best C cross compilers for embedded systems, point your WWW browser at http://www.hitech.com.au, or email info@hitech.com.au