Flash memory is primary or secondary memory

Storage architecture

In computer technology, memories are used to store information in binary form. As a rule, these are followed by zeros and ones. Programs and information are saved. Depending on the processing status, this data is located in different places within the memory architecture of a computer system.

An optimal data storage medium would consist of a data carrier that can permanently hold large amounts of data and at the same time is very fast. All three properties have been worked on again and again in the development of data storage systems. Unfortunately, all requirements could never be met together. Either the memory was too small, too slow or lost its memory when the power supply was switched off. For this reason, a two-tier storage architecture has been developed that distinguishes between primary storage and secondary storage.

  1. Primary storage
    • Buffer memory (cache in the processor)
    • Random Access Memory (RAM)
  2. Secondary storage
    • Read-only memory
    • Mass storage
    • Removable storage

Primary storage (cache, main memory)

Primary storage is intended for data and instructions that are about to be processed by the main processor or that have already been processed. These include the cache and the main memory. The cache is integrated in the processor and serves as an intermediate memory, which ideally works at processor speed and ensures that the processor is always fed with data and program code. This prevents the processor from idling.

Before the program code and data enter the processor for processing, the main memory serves as a data store. The size of the main memory determines the amount of data that can be kept for the processor. Executing programs and processing data from the main memory results in a speed advantage that cannot be achieved when reading and storing programs and data from secondary data memories. The main memory is therefore faster than secondary memory.

The specialty of the main memory lies in the random access and in the fast changeability of the memory contents. On the other hand, it loses the contents of the memory if the operating voltage is lost. For example when turning off the computer. If the data is to be stored permanently in the main memory, then it must be written by the main processor from the main memory to a secondary memory.

In a computer, the connection of the data memory to the processor has always been a bottleneck. In practice, however, this has little effect on the overall performance of the system. The combination of jump predictions by the processor in the program code and, at the same time, large, staggered caches absorb a large part of the requests to the main memory and the hard disk. The data from the main memory is usually in the processor's cache before it is called up. If a program has to wait for data, the processor's arithmetic unit does something else in the meantime. In this way, the inadequate storage connection is concealed.

Secondary storage (permanent storage, mass storage)

Secondary memory is the external data memory of a computer, which the main processor does not access directly, but via input and output interfaces. Secondary storage is permanent storage and at the same time also mass storage. Secondary storage is used to permanently store data that is not currently being processed. Compared to primary storage (working memory), it has a higher storage capacity, can permanently store the data even without an energy supply and therefore works much more slowly.

Secondary storage, such as a hard disk, provides a lot of storage space. The hard disk in particular is optimized for high storage capacities. It's about being able to save as much data as possible permanently at the lowest possible price. The writing and reading speed only plays a subordinate role. The access time is limited by the interface and the mechanics and does not allow any working speed that is usual for the processor.

Data on secondary storage is usually organized into files and directories using a file system.

A distinction is made between secondary storage systems based on their technical processes:

  • Mechanical secondary storage
  • Secondary optical storage
    • CD-ROM / CD-R / CD-RW
    • DVD-ROM / DVD-R / -RW / DVD + R / + RW / DVD-RAM
    • Blu-ray Disc / BD-R / BD-RE
    • Holographic memory
  • Magnetic secondary storage
    • Floppy disks
    • ZIP
    • Hard drives
    • Tape / magnetic tape
  • Semiconductor secondary storage

Almost all secondary storage is either magnetic or optical. Mechanical secondary storage is only museum value. Semiconductor memories such as flash memory, which can permanently store data without an energy supply, are pioneering. However, we are still at the beginning of the technical development.

Other related topics:

Everything you need to know about computer technology.

Computer technology primer

The computer technology primer is a book about the basics of computer technology, processor technology, semiconductor memory, interfaces, data storage devices, drives and important hardware components.

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Everything you need to know about computer technology.

Computer technology primer

The computer technology primer is a book about the basics of computer technology, processor technology, semiconductor memory, interfaces, data storage devices, drives and important hardware components.

I want that!