Top "Opcode" questions

The binary number that represents a machine instruction for a specific processor type.

How to interpret the opcode manually?

77f4bcbc 8945fc mov dword ptr [ebp-4],eax And here's the rule: 88 /r MOV r/m8,r8 2/2 Move byte register …

assembly opcode
SAL/SAR vs SHR/SAR in assembly 8086

I am learning assembly language (specific to x86). I have understood that the SAL and SHL works in similar way (…

assembly x86-16 opcode
execute binary machine code from C

following this instructions I have managed to produce only 528 bytes in size a.out (when gcc main.c gave me 8539 …

c gcc assembly nasm opcode
PowerPC opcode table?

I am interested in developing a PowerPC emulator for my own learning purposes. I've found a fair amount of resources …

assembly disassembly powerpc instruction-set opcode
mov instructions with byte destination for immediate to memory

I am reading a textbook entitled Introduction to 80x86 Assembly Language and Computer Architecture by Richard C. Detmer I have …

assembly x86 opcode mov addressing-mode
x64 instruction encoding and the ModRM byte

The encoding of call qword ptr [rax] call qword ptr [rcx] is FF 10 FF 11 I can see where the last …

assembly x86 x86-64 machine-code opcode
Opcode for negative jump

I'm trying to create some shellcode where I need to jump back (a negative jump). I want to jump 2400 bytes …

assembly x86 opcode shellcode
How to read the Intel Opcode notation

I am reading some material about Intel Opcodes of assembly instructions, but I cannot understand what does it mean that …

assembly x86 intel opcode machine-code
How do I get full assembler output in gcc?

I know I can get the assembler source code generated by the compiler by using: gcc -S ... even though that …

gcc assembly opcode