Chapter 1: Architecture Flashcards
What is Architecture?
The Architecture is the programmers view of the microprocessor
Fundamental information about the microprocessor often required?
- The instruction set – a set of commands like a programming language. They tend to be very basic commands such as add or subtract or jump.
- Locations of memory containing data
Different architectures:
- x86
- PowerPC
- ARM
- MIPS
- SPARC
x86?
– the majority of personal computers are based around this architecture owned by Intel which started out in 1978 and has been continuously improved ever since.
PowerPC?
– prior to 2005/6 Apple PCs were built using this architecture made by Motorola & IBM.
ARM?
most dominant architecture used in mobile phones, since it uses less power and creates less heat. Used by Apple and Samsung.
MIPS?
has been used by Sony in some of their Playstation products.
SPARC?
developed by Sun Microsystems
Microprocessors: Connections to memory etc.
In a computer the microprocessor is separate to the memory and these elements are all connected together by the system bus, typically a number of parallel electrical wires.
The microprocessor controls the voltages on each of the electrical connections on the bus to read or write information from memory.
Microprocessors: Solitary functionality issues?
The microprocessor is pretty useless on its own; it needs memory, a clock signal to control the timing of the processor, and other peripheral devices so that it can communicate with the real world.
These are all the sorts of things you would see on the motherboard if you opened up your computer.
How is a microcontroller different from a microprocessor?
In contrast, a microcontroller consists of a microprocessor and all these other essential items on a single piece of silicon. This allows them to be embedded into systems out of sight of the user. The PIC16F84A that you will be using in the laboratory sessions is an example of a microcontroller.
Examples of where microcontrollers are used?
- Toys
- Anti-lock braking system
- Washing machine
EXAMPLE
Microcontroller at work:
The idea: You try to slow down your car on a slippery road, say ice or rain. You put on the brakes, the wheels stop turning suddenly because instead of rolling, they are now skidding across the surface. Your brakes are no longer slowing the car down. You can stop quicker by releasing the brakes so that the wheels continue to turn and then braking more slowly.
The solution with a microcontroller: Continuously read a sensor measuring the wheel speed to detect if the car is skidding. If skidding then reduce braking pressure to that wheel. If not, then allow normal braking. Repeat continuously.
Out of Von Neumann and Harvard, which is more susceptible to attack?
Von Neumann is more susceptible as it is easier to place a malicious file into the memory that can then be immediately compiled without going through the CPU.
The security of the system bus can also be questionable.
