ch3 Flashcards
what is memory cache
high speed memory external to the processor that stores data which will be needed by the processor again
random access memory
primary memory unit that can be written to or read from
read-only memory
primary memory unit that can only be rea from
properties of RAM
1- volatile: data is stored temporarily
2- data can be read from and written to: data stored can be changed by the user or the computer
3- it stores data that is currently in use
description of DRAM
it is made of tiny capacitors and transistors. capacitors hold the bits of information (0 and 1) and transistors act like a switch; they allow the chip control circuitry to read the capacitor or change the capacitor’s value
advantages of using DRAM over SRAM
1- less expensive to manufacture
2- has higher storage density
3- has higher memory capacity
properties of SRAM
uses flip-flops which hold each bit of memory
advantage of using SRAM over DRAM
1- does not need to be constantly refreshed
2- faster data access time
3- consumes less power
properties of ROM
1- non volatile: memory is permanently stored
2- stores start up data such as BIOS
3- data is only read from which means is cant be changed by the computer or the user
Programmable ROM (PROM)
type of ROM chip memory that can be programmed only once
Erasable PROM (EPROM)
type of ROM that can be
programmed more than once using ultraviolet (UV) light.
difference between primary and secondary storage devices
1- primary can be directly access by the cpu while secondary cannot
2- primary storage is much larger
3- primary memory access time is much faster
Electronically erasable programmable read-only
memory (EEPROM)
read-only (ROM) chip that can
be modified by the user, which can then be erased and
written to repeatedly using pulsed voltages.
benefits of using an SSD rather than an HDD
-are more reliable (no moving parts to go wrong)
-are considerably lighter (which makes them suitable for laptops)
- do not have to ‘get up to speed’ before they work properly
- have a lower power consumption
-faster data access
benefit of EEPROM in the embedded
can be erased and reprogrammed several times
possible to reprogram
without removing it from the device
