Purposes, features, and uses of internal components
Most of the device categories contain broadly the same types of components, and as such, their purposes and features are similar. We will start by identifying the common elements to all of the devices (and identifying any system-specific features), and then list any system-specific types of component after.
Common Internal Components
Central Processing Unit
A CPU (often referred to as simply processor) is a device which decodes and executes instructions contained in a computer program. Every type of computer system contains a CPU of some description. The implementation of CPUs in different system types varies according the the system’s purpose:
| System type | Features |
|---|---|
| PC | Usually a single CPU package which contains multiple cores allowing multiple tasks to be computed simultaneously. Power consumption is in the range of 30-200W. Likely to be an ‘x86’ compatible processor (meaning it understands a complex instruction set – CISC). Clock speed in the range of 1GHz – 5GHz. |
| MFD | Usually a reduced instruction set (RISC) processor as opposed to x86 Depending on the device, may be single core or multi core Power consumption in the range of 5-50W |
| Server | Specialist versions of x86 and x64 (CISC) CPUs Contain additional hardware specific to server requirements, for example increased cache memory, virtualisation hardware, higher core counts, ability to be used in motherboards that contain more than one CPU package Clock speed and power consumption in the same bracket as PC CPUs |
| Mobile devices | Far more variable in terms of type – for instance, mobile phones are almost all RISC-based designs, whereas laptops are almost always CISC-based. Where CISC-based designs are used, they tend to be specialised versions of PC designs – for example, reduced operating frequency at rest (allowing for lower power consumption), reduced core counts |
RAM
All modern computers utilise Random Access Memory (RAM) in order to provide temporary storage of program data – instructions and data. RAM is volatile primary storage.
As a program is launched, its data is copied from secondary storage (HDD, SSD, network) into RAM, in order for the CPU and other components to access it.
With the exception of MFDs which are typically embedded systems, most computer systems typically contain multiple gigabytes of RAM: 8GB is normal for a PC or laptop computer, mobile phones contain in excess of 3-4GB, whereas a server will contain far more – often more than 64GB.
For the purposes of brevity, RAM is differentiated by the following characteristics:
| Characteristic | Explanation |
|---|---|
| Capacity | The amount of storage provided by a ‘stick’ of RAM (so-called because of its physical appearance). |
| Speed/standard | The ‘standard’ refers to DDR (double-data-rate), DDR2, DDR3, DDR4. Each progressive version of the specification increases the amount of data that can be transferred from the RAM in each cycle. Speed is more complicated: it is composed of two factors – a clock speed (the number of cycles per second that the RAM can fulfil, and is measured in MHz, although it is in the GHz range – e.g. 2400MHz), and its CAS latency. CAS latency refers to the latency (delay between requesting data and it being retrieved) and consists of several values, which govern the initial latency, and the latency between successive retrievals. It is common for high-performance computers to use expensive RAM with not only a higher clock speed, but also a lower latency. |
| Error correction | Servers utilise special RAM, called ‘Error Checking and Correction’ (ECC) RAM. Whereas a normal RAM stick contains 8 (or 16 or 24 etc) RAM chips, ECC sticks usually contain 9 (or 18, or 27 etc). The additional chip is used to store error-checking data which is calculated by an embedded processor on the memory stick), which allows the memory to identify and correct errors which may occur as a result of power fluctuation or radiation. This is expensive technology, and therefore only used in mission-critical scenarios, such as servers where may people depend on the service being available. |
Secondary storage
Almost all devices need some sort of secondary storage – this is used to store information in a non-volatile fashion, meaning that it is not lost when the power is shut down.
For example, an MFD which incorporates a fax provision may need to store received messages until such time that they can be printed. It would not be appropriate to rely on RAM for this, as if there was a power outage, received messages would be lost.
Secondary storage will refer to one of:
- Hard Disk Drive – high capacity, magnetic media
- Solid State Disk – extremely fast, lower power consumption, highly reliable storage utilising memory chips for storage rather than magnetic media
Graphics adapter
Any modern device with the ability to provide a visual output (on a screen), requires hardware to generate the image – this is the role of a graphics adapter. A graphics adapter’s job is to turn binary data into a signal that can be displayed as an image.