FIT1047 Study Guide - Final Guide: Computer Memory
Memory
Saturday, 26 May 2018
4:50 PM
• Memory is a sequence of locations, each of which has an address usually starting from 0
• Each location can store one data value of a fixed width (fixed number of bits)
• CPU can read a value currently stored at a location, and overwrite it with a different value
Addressing memory locations
• An address is an integer that references one unique memory location
• Addresses are usually consecutive numbers starting at 0
• In most architectures, one location stores one byte
• Each byte has its own address. This is byte addressable memory
• MARIE
o One memory location stores one word
o Each word has its own address word addressable memory
o MARIE uses 16 bits (2 bytes) for each word
• Other words may be 32 bits or 64 bits
• In order to address 2^n memory locations, we always need b nits for the addresses
RAM (Random Access Memory)
• Emphasises that the CPU can access any memory locations in RAM (read from or write to) in
the same amount of time
• RAM modules are made up of multiple chips
o L x W - L is number of locations, W is number of bits per location
o 2K x 8 means 2x2^10 locations of 8 bits each
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