Hardware and the Computer

Hardware and the Computer

1. The CPU

   • The letters CPU stand for Central Processing Unit,
   • The CPU executes or runs commands for the computer and it co-ordinates and controls all operations for the computer
   • The CPU's speed is measured in Hz or Hertz
   • Cores and the CPU
     • Cores execute instructions such as add, move data, and branch. Within the chip, each core operates along side the other circuits such as cache, memory management, and input/output ports.
     • Cores in a CPU are separate processes within the CPU
   • The processor uses a special register called the processing register to remember which instruction it should run next.
   • The performance of a CPU can be affected by many factors such as the amount of cores, its clock speed and the amount of cache.
   • The ALU
     • The ALU Performs arithmetic calculations and logical comparisons
     • ALU stands for arithmetic logic unit
   • Cache
     • Cache is a small amount of fast on-board memory often on or near the CPU
   • Clock Speed
     • Clock speed is the operating speed of a computer or its microprocessor, expressed in cycles per second
     • MHz = Million Cycles per Second
     • GHz = Billion Cycles per Second
     • KHz = Thousand Cycles per Second
     • Hz = 1 Cycle per Second

2. RAM and ROM

   • RAM is Random Access Memory
     • The operating system, running programs and data currently being used is all stored in RAM
       • All of the stuff stored in RAM is lost if the computer loses power or is turned off, this type of memory is called volatile.
         • You can read and write data to RAM
   • ROM is Read Only Memory
     • Computer bootup instructions are stored in ROM
       • When the computer is shutdown or looses power all of the stuff stored in ROM is kept and retained, this type of memory is called non-volatile
         • You can only read data from ROM

3. Secondary Storage

   • Secondary storage is storage that is not directly accessible by the CPU, because it is not accessed via the input/output channels eg, Harddrive or USB
   • Secondary storage can be things like the harddrive or the harddisk, it is storage where stuff is permanently stored, so its not RAM.
   • The three main types of storage are: Magnetic, Optical and Solid State
     • Magnetic Storage
       • Disk contains concentric circles called tracks and each track is divided into sectors with diskheads pounted on arms to read and write data
       • Hard Drives are magnetic storage
       • Its Cheap, vast storage capability, fast write speed but Lots of mechanical parts, durability an issue, sealed unit due to disk head and platter precision and not very portable.
       • 500GB - 3TB