Hi friends,my prof has just given me the code that changes the size of the cursor.....the code is heavy in the use of registers ,inregs,outregs etc and I dont even know where to start googling from...so can you tell me what inregs and outregs do and just give me a start

sounds like you got some very very old and ancient MS-DOS code, such as this program. To make effective use of the REGS union you need to learn some assembly language, and especially about software interrupts 16 and 21.

Those are not useful with any of the moders 32-bit compilers. If you are using MS-Windows then you should learn the win32 api console functions.