Wendy J Olend wrote... >I've just started my "Designing with Microprocessors" class, and guess = what >processor we're working with. The Motorolla HC11. This means I get to >spend the summer wresting with 2 different instruction sets, 2 different >architectures and a host of other confusing incompatibilities... I worked with the 68HC11 for years, and in some ways it's a lot more straightforward than PICs. =20 In some ways, of course, it's not, particularly hardware: if you implement a memory-mapped system with external RAM, EPROM, and I/O (typical in what I was doing), you've got some hardware design and construction to do that's a lot more involved than working with PICs. PICs are compact by comparison. On the plus side, I expect you'll find the 68HC11 has some amenities that make it a bit more programmer-friendly: * No pesky bank bits to fret over; * No pesky page bits to fret over; * A REAL stack that you can actually use for parameter passing, with a stack pointer you can manipulate at will; * Two accumulators (A and B, each analogous to the PIC's W register) that can be used as a single 16-bit register for some operations; * Two index registers (X and Y, somewhat akin to FSR/INDF on the PIC, that can be used to hold addresses; * All memory and I/O (whether on-chip or external) is in a single, contiguous 64K address space; * On-chip RAM is allocated as a single, contiguous block instead of in separate banks as in the PIC; * A nice set of conditional branches that (for me, at least) make programs "seem" a lot more logical; * Table look-ups are a breeze; and * The 68HC11 has on-chip peripherals (timers/counters, SPI, UART, etc.) that are very similar to those on the PIC. I migrated from 68HC11s to PICs because of the PIC's lower cost, lower power consumption, higher speed, its compactness and the availability, in the newer PICs, of enough RAM and flash ROM to do the jobs I have at hand. I **REALLY** like working with the PIC as it allows me a processor solution for tasks that would be way too small to consider using a 68HC11; and its high execution speed also allows me to do things with it that would be impossible with the HC11. (A fast, 4 MHz 68HC11F1 will execute an instruction in anywhere from 500 nanoseconds to 1.75 microseconds, whereas a 20 MHz PIC16F877 executes 5 instructions every microsecond.) That said, the 68HC11 was significantly easier to program than the PIC is right now, at least for me. Maybe when I have a few more PIC projects under my belt I'll feel differently; presently I have just one commercial PIC-based product out and a start on two others, plus some homebrew doohickies on my workbench that blink, beep, or go "phthththttt". > I'm just barely comfortable with the PIC. It'll be a miricle if = I >can do ANYTHING, with either processor, by the time August rolls around. My bet is you've got it backwards: I suspect you'll be able to do a LOT more, with BOTH processors, than you can now imagine. Cheer up! >Pray for me , guys. Nah. You don't need prayers. You just need some online encouragement. When you've learned your first microprocessor, you know only that one processor (unless you've got a head full of theoretical and historical computer science lore, which I did not). When you've learned your second, you begin to see common threads and can start to generalize; you will know a lot more than just the two microprocessors. Once you've learned your third (at least this is my opinion) you've pretty well learned them all, except for such esoterica as digital signal processors and the like. Learning any other chips, from that point on, becomes pretty routine. Good luck with the course, and enjoy. Dave -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics