I'm a little bit confused because I'm french and we have some clear transaltion hahaha :)

A bit is only 0 or 1 ??
A byte is 8 bits ??

What about the instruction in hexadecimal ...
like 45, this means JMP

how many bits does an instruction take ??
Is the lenght variable or not ??

Thank you !!!!
Posted on 2001-10-10 17:57:54 by pas enregistr
>>A bit is only 0 or 1 ??
Correct.

>>A byte is 8 bits ??
Also correct.

>>What about the instruction in hexadecimal ...
>>like 45, this means JMP
>>how many bits does an instruction take ??
>>Is the lenght variable or not ??

The JMP opcode you mentioned above takes 1 byte for the instruction, i dunno about how many bytes the operand takes, but it will be in various bits of doco. Some instructions take two bytes + operand, i dunno if any take three bytes (i haven't memorized all the opcodes....)


sluggy
Posted on 2001-10-10 19:07:18 by sluggy
45 means "inc ebp" and is a one-byte instruction.
EB is a near jump, and has a one-byte (signed, relative) operand.
E9 is a near jump, and has a four-byte (signed, relative) operand.

Opcode length varies a lot, but it will always have byte granularity.

I suggest you take a look at the intel manuals, they explain this
very well.
Posted on 2001-10-10 19:29:06 by f0dder