What are the main differences between x86, arm and avr assembly? How difficult is one to learn if you know another one?
x86, ARM, and AVR are different processor architectures, each with its own assembly language. Assembly language is a low-level programming language designed for a specific processor architecture. Here are the main differences between x86, ARM, and AVR assembly languages:

1. x86 Assembly:
- x86 is a complex instruction set computing (CISC) architecture used in Intel and AMD processors.
- It has a large number of instructions and addressing modes, which allows for complex operations to be performed in a single instruction.
- x86 assembly language has a rich set of registers, including general-purpose registers (GPRs), segment registers, control registers, and floating-point registers.

2. ARM Assembly:
- ARM is a reduced instruction set computing (RISC) architecture used in many embedded systems and mobile devices.
- ARM assembly language is simpler than x86 assembly language, with fewer instructions and addressing modes.
- It has a large number of general-purpose registers (16 in ARMv7 and 31 in ARMv8) and supports multiple register operations (e.g., load/store multiple registers at once).
- ARM assembly uses a load-store architecture, meaning that data must be loaded into registers before being operated on, and the results must be stored back to memory.

3. AVR Assembly:
- AVR is another RISC architecture used in microcontrollers, such as those from Atmel (now part of Microchip).
- AVR assembly language is even simpler than ARM assembly, with a smaller number of instructions and addressing modes.
- It has fewer general-purpose registers (32 in total) than ARM and does not support multiple register operations like ARM.
- AVR assembly also uses a load-store architecture, similar to ARM.

Learning one assembly language can make learning another one easier because many concepts, such as registers, memory addressing, and control flow, are common across different architectures. However, each assembly language has its own unique syntax, instructions, and addressing modes, so you will still need to learn those specifics when switching between architectures.

In general, learning x86 assembly can be more challenging due to the larger number of instructions and complexity. However, once you are familiar with x86 assembly, learning ARM and AVR assembly languages should be comparatively easier due to their simpler instruction sets and more regular syntax. Conversely, if you start with ARM or AVR assembly, you may find it easier to understand the fundamental concepts, but you will still need to learn the additional complexity of x86 assembly when transitioning to that architecture.