Introduction to Computer Systems

Review these notes. For maximum benefit, go through these notes interactively, thinking about and answering the questions at the bottom of each page. These notes are an experiment in applying the "programmed learning" method to web-based computer aided instruction. The subject is Java Programming for beginning programmers. The content is intended to start beginning programmers out on the track to professional-level programming and reinforce learning by providing abundant feedback. Java is a programming language that is used often in professional practice.

Memory

Answer:

The first microprocessor chip, the Intel 4004, had 2300 transistors in 1971.

 

Memory

The processor performs all the fundamental computation of the computer system. Other components contribute to the computation by doing such things as storing data or moving data into and out of the processor. But the processor is where the fundamental action takes place.

A processor chip has relatively little memory. It has only enough memory to hold a few instructions of a program and the data they process. Complete programs and data sets are held in memory external to the processor. This memory is of two fundamental types: main memory, and secondary memory.

Main memory is sometimes called volatile because it loses its information when power is removed. Secondary memory is usually non-volatile because it retains its information when power is removed.(However, it needs power when information is stored into memory or retrieved from it).

Main memory is sometimes called main storage and secondary memory is sometimes called secondary storage or mass storage.


  • Main memory:
    • closely connected to the processor.
    • stored data are quickly and easily changed.
    • holds the programs and data that the processor is actively working with.
    • interacts with the processor millions of times per second.
    • needs constant electric power to keep its information.
  • Secondary memory:
    • connected to main memory through the bus and a controller.
    • stored data are easily changed, but changes are slow compared to main memory.
    • used for long-term storage of programs and data.
    • before data and programs can be used, they must be copied from secondary memory into main memory.
    • does not need electric power to keep its information.


Question 5:

Which is fastest? Main memory or secondary memory?

Which is largest? Main memory or secondary memory?