Written by Stefan Ohlsson 1997 

  
Image of a Single In-Line Memory Module 

What is RAM (Random Acess memory)? 
Ram chips is one of the two types of memory your computer uses to store 
Information. The other type of memory your computer use is your hard or floppy drive. The microprocessor is getting all its instructions from RAM. All data contained in documents and all other programs must be stored in RAM before the software can use the processor to manipulate that data. 
The PC is using binary numbers for all its operations. It simply means 0's and 1's. 
A computer consists of a large collection of switches. An open switch represents a 0 and a closed switch represents a 1. 1's and 0's is the computer's machine language. 
The operating system and software use a convention known as ASCII or American Standard Code for Information Interchange. This convention interprets the computer language to certain letters. Without this convention an A letter will end up on the screen as the binary number 01000001. 
When you turn on your computer is RAM a tabula rasa or a blank sheet. The 
Memory is filled with 0's and 1's from the operating system and other programs that 
Are working. When you turn off your computer all information stored in RAM will disappear.  

Writing Data to RAM - Step By Step 

1. The software you use in combination with the operating system sends a burst of  electricity along an address line. An address line is a microscopic line of  electrically conductive material etched into a RAM chip. This burst sent by the  operating system and other software identifies where to record data among the  many address lines in a RAM chip. 

2. The electrical pulse closes (turn on) a transistor that's connected to a data line at  each memory location in a RAM chip where data can be stored. 

3. The software sends burst of electricity along selected data lines while the  transistors are turned on. A bit, either a 1 or 0, represents by the burst. 

4. When the electrical pulse go through an address line along which a transistor has  been turned on, the electrical pulse flows through the transistor and charges a  capacitor. A capacitor is an electronic devise that stores electricity. This process repeats itself continuously in order to refresh the capacitor's charge. Without these repeated charges the capacitor's charge will slowly leak out. Each charged  capacitor represents a 1 bit. An uncharged capacitor represents a 0 bit. 

Reading Data from RAM - Step By Step 

1. When you are running a program that wants to read data stored in Ram another electrical pulls will be sent along the address line and turn on the transistors  connected to the address line. 

2. On every location along the address line that there is a capacitor holding a charge,  an electrical pulse will go through the turned on (closed) transistor and through the  address line connected to it. 

3. The software in the computer identifies which data lines the pulses come from. It interprets each pulse as binary numbers. A 1 when a pulse is sent through a data line and a 0 when a pulse is not sent. There are eight data lines into RAM and the combination of 1s and 0s forms a single byte of data.