Components of a System Unit

A. The CPU
   1. The Control Unit
   2. The Arithmetic-Logic Unit
   3. Machine cycle
      Fetch (memory to Control Unit)
      Decode (Control Unit)
      Execute (ALU)
      Store (ALU to memory)
   4. Pipelining

B. Memory
   1. holds data, instructions and information
   2. volatile, non-volatile
   3. capacity differs from one machine to another
   4. registers (supplement memory in the CPU)
   5. The processing cycle (looking up addresses and using contents)

C. Binary encoding (on/off, 1/0 states)
   1. units of measure for capacity (bits and bytes)
      a. kilobyte (1000 bytes, KB as in 640 KB)
      b. megabyte (1000000 bytes, MB as in 16 MB)
      c. gigabyte (1000000000, GB)
      d. terabyte (1000000000000, TB)
   2. binary coding schemes (ASCII, UNICODE)

D. The System Unit
   1. system board (mother board) - holds all major chip components
   2. microprocessor chips
      a. Intel family (286, 386, 486, Pentium)
      b. math coprocessors
      c. Motorola family (68020, 68030, 68040)
      d. Power PC
      e. CISC vs. RISC chips
   3. RAM chips
      a. can be increased with SIMMs
      b. types of RAM
         i. conventional (640K)
         ii upper memory (640K to 1 Meg)
         iii. extended memory (directly accessible above 1 M)
         iv. expanded memory (swapping up to 32M with upper memory -
            a workaround for older machines)
      c. cache memory - reserved space in RAM for high-speed processing
         level 1 vs. level 2
   4. ROM chips
      a. PROM - programmed by manufacturer
      b. EPROM - eraseable for reprogramming but not accessible by user
   5. System clock
      a. system operation speed (MHz - million cycles per second)
      b. a function of the microprocessor
   6. Expansion slots and boards
      examples: memory expansion boards, network adapter cards, video boards,
        sound boards, CD-ROM adapters
   7. Bus connections (for data transfer within the CPU)
      ISA, PCI, AGP, USB
   8. Ports (parallel, serial, SCSI)