[ILUG-BOM] Debug for Linux?

Hi! I'm studying 8086 in Microprocessor II Usually we write simple programs using MS-Dos's debug "command" Is there a parallel Linux utility ? Also are there any assemblers like MASM TASM ?

I would also like to clear some doubts:

1. In DOS we use interrupts like int 20,int 21 etc.. which perform certain tasks. Are these interrupts apllicable to Linux also?

2.In Assembly since we deal directly with CPU isn't it a security risk? (I have come across some debug routines which clear CMOS , destroy the hard disk partitions... !)

3.Why there r so many books written for Assembly Programming which are specific to Dos based Assemblers and debug? Is Unix implementation for Assembly Programming difficult ?

Please enlighten.