What do we mean by "RISC”?
It means Reduced Instruction Set Computer, as oposed to CISC (Complex Instruction Set Computer). A RISC proccessor has a limited set of instructions, most of them being atomic (i.e. they execute in a single clock period). Search the web for "risc vs cisc" if you want to learn more about this.
What is Flash Memory?
It's a technology of static re-writable memories. This means you can turn of the power of the memory, and data won't get lost (like a ROM) and you can read and write the memory several times (like a RAM).
I would like to know that what do we mean by " Brown Out Reset"?
Brown out reset is an internal circuit on the PIC that resets the PIC when it detects a brownout on the supply voltage
What does DC in DC - 20Mhz clock input or DC-200ns instruction cycle means?
That means you can run your PIC at any speed you like from DC (direct current) to 20 MHz (5 mips)
What is the difference between FLASH / EEPROM memory?
Well, the differences are subtle. Read it from here:
**broken link removed**
What do we mean by "Eight Level deep hardware Stack”?
The stack is a data structure that stores pogram instruction adresses. When you call a subrutine in your program, the proccessor must remember where it was before jumpig to the subrutine so it can resume the program execution once the subrutine finished. It "remembers" the position of the program because it saves the address of that instruction on the stack. The stack being 8 level deep means you can call a subrutine being inside other subrutine, being inside other subrutine,..... 8 times.
What do we mean by DIP,SOIC,SSOP,PLCC,QRP,I/O/P?
Those are standard chip packages (some smaller, some rectangular, surface mount, through hole, etc)
What do we mean when we say "PIC has 2K X 14 words Flash Program Memory”?
It means you can store a program as big as 2K (2048) instructions. Each instruction is 14 bits wide