1.2 Memory & 1.3 Storage

1.2 Memory & 1.3 Storage

1. 1.2 Memory

   • RAM contains programs, instructions and data that are currently being worked on (in use). RAM is volatile meaning that when the power is removed then all data is lost.
   • ROM (Read Only Memory) is usually a flash memory chip on the motherboard that contains instructions needed to start up (boot) the operating system. ROM is non-volatile meaning that when power is removed, data is retained on the chip.
     • The ROM chip in a PC is usually called BIOS
   • Flash memory refers to memory that is solid state (i.e. No moving parts) that retains data even when power is removed.
   • Virtual memory is for when the computer runs out of available RAM and so uses part of the HDD (Hard Disk Drive) instead. This is not desirable however, as the HDD is much slower than RAM

2. 1.3 Storage

   • Primary Storage (Sometimes called Main Memory) refers to the memory areas that the CPU can access very quickly (Cache, RAM and ROM). Primary storage has the fastest read/write speeds and is mostly volatile.
   • Secondary Storage is non-volatile – it’s where all data (operating systems, applications and user files) are stored when not in use (e.g. HDD, USB Flash drive, SD card). Read/write speeds are much slower compared to primary storage.
   • Types of storage
     • Optical
       • CD (700MB), DVD(4.7GB), Blu-Ray(25GB)
       • Cheap per GB and portable. Can even be given away on magazines!
       • Prone to getting scratched (not durable) and is slower than magnetic or solid state
       • Use is declining
     • Magnetic
       • High capacity and reliable. HDDs are generally around 2TB at the moment
       • Portable versions of HDDs are useful for backing up and transporting large amounts of data
       • Sensitive to being dropped (i.e not durable)
     • Solid State
       • No moving parts (only uses memory chips, no spinning motors that are noisy/generate heat)
       • Fast, reliable and highly portable (light and small).
       • SD cards and USB Pen drives aren’t nearly as fast as SSDs, but still are very useful!

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