Texas Instruments 3000 - Manual (Page 156)

F
Configuring Memory
Introduction
Computers handle information as strings of binary digits: ones and zeros. A single I or 0
is refer-red to as a bit, the smallest unit of information handled by the computer. A group
of eight bits, referred to as a byte, is used to represent single characters or numbers such
as "A" or "5".
The size of the computer's RAM (main memory) is measured by the number of bytes the
memory can store. Since this number usually involves thousands and even millions of
bytes, the letter K (kilo) is used to represent thousands of bytes and M (mega) is used to
represent millions of bytes. Because of differences between the binary and decimal
number systems, one K byte actually represents 1024 bytes, and one M byte represents
1024 K bytes. (These values are abbreviated as KB and MB in this manual.)
Computers use two main types of internal memory: ROM and RAM. (Although floppy
drives and hard disk drives are usually incorporated into a computer's case or cabinet,
these memory devices are external memory and could theoretically be located anywhere.)
ROM (Read Only Memory) - ROM is memory that permanently stores programs or data
on integrated circuits mounted on the computer's system board. Information is
programmed into the circuits in the manufacturing process and cannot be changed by the
user.
RAM (Random Access Memory) - RAM is memory that temporarily stores data or
programs-that is, information can be easily erased and rewritten. Also called main
memory, conventional memory, or system memory, RAM is used by the computer to store
data and programs only while the system is running. When the power is turned off, any
information stored in RAM is lost.
Configuring Memory F-1