Computer hardware are the physical parts of a computer.
Computer Hardware Components
Computer hardware components can be:
- Processors
- Memory
- Peripheral
- Interfaces
Processors
A processor is composed by at least a computer processing unit (CPU). It may also have CPUs.
You can read about processors on this post.
Integrated Circuits
An application-specific integrated circuit (ASIC) is a integrated circuit customized for a particular function.
A field programmable gate array (FPGA) is a type of integrated circuit that can be programmed or reprogrammed after manufacturing. It allows to created reconfigurable hardware to implement custom digital circuits. You can read more about FPGA on this post.
Memory
Types of memory:
- Cache
- Main memory
- Secondary memory
Cache Memory
There are different protocols for cache coherence.
There are different cache memory level: L1, L2 and L3.
MESI protocol is a cache coherence protocol. It is an acronym for Modify, Exclusive, Shared, Invalid.
Main memory
Random Access Management (RAM). There are
Secondary Memory
RAID. You can read about RAID on this post.
Hardware Interfaces
A chipset connects different elements.
Chipset MCH manages main memory and GPU. These tasks are delegated from the CPU to this chipset.
Chipset ICH4 manages the in & out (I/O) operations such as secondary memory, network, audio or USB devices. These tasks are delegated from the CPU to this chipset.
A bus is a communication system that transfers data between components inside a computer or between computers.
An computer bus interface connects the components of a computer. You can read this post about internal computer bus interfaces.
Computer Architecture
Structured Computer Organization. Andrew Tannenbaum has a book on this subject.
Computer architecture is an abstraction that describes the components of a computer and the interaction between them.
Computer Architecture Models
Computer architectures:
- Harvard architecture
- Von Neumman architecture
Harvard Architecture
Harvard architecture features two separates buses and memories for the instructions and the data.
Von Neumann Architecture
Von Neumann architecture or Princeton architecture features a single bus and memory that connects to both the instructions and the data. It reduced complexity.
A Von Neumann architecture, single bus structure or stored program proposes a link between processing, storage and I/O that communicates through a bus. They share direction, data and control through the bus.
The Von Neumann bottleneck refers to the situation where the performance is reduced because the same medium is shared by the instructions and the data.
Memory is organized in addresses.
If a bus has n bits for the address, there are 2^n addresses available. Engineers define that the standard number of bits is 32 or 64 bits.
Data, that includes instructions, are also limited to m bits, a maximum of 128 bits.
The physical capacity of memory (PCM) is:
PCM = 2 ^ n * m bits
Control Unit (CU) uses a specific Instruction Set Control (ISC) is contained by a CU.
A decod is linked to a CU generates 2^m signal controls from m bits of instructions.
A clock is linked to a CU and generates each pulse. The greek letter tau represents the cycle time. It should be at shortest as possible. We are currently in the magnitude of nanoseconds.
Frequency is the inverse of time. We are currently working the magnitud of GHz. The top is 4 GHz.
This limit can be expanded through adding cores, but the improvement is not lineal.
The Arithmetical Logic Unit (ALU) is connected to the CU. It receives the decoded instruction and the clock signal.
ALU may be also referred as Processing Unit (PU).
ALU performs:
- Arithmetical (sums and/or semisum)
- Logic (doors)
- Shifters
Examples of logic doors are AND and OR.
The Control Processing Unit (CPU ) is composed of the CU and ALU.
Computer Types by Power
There are these kinds of computers, in historical order:
- HPC
- Supercomputers
- Mainframe
- Grid computing
- Minicomputers
- Microcomputers
Downsizing means using smaller computers working together that reach the same performance as a larger computer.
Rightsizing means finding the right balance in price between small-size computer and high-size computer.
High Performance Computing (HPC)
You can read a post about high performance computing (HPC).
Minicomputers
You can read a post about minicomputers.
Microcomputers
You can read more about the 8-bit home computers, that were 8-bit microcomputers, on this post.
Embedded Systems
A microcontroller or microcontroller unit (MCU) is a small computer on a single integrated circuit. An MCU usually includes a CPU, RAM, EPROM and I/O in the same chip.
A system-on-chip (SoC) would be an extended concept of a microcontroller that adds extra functionality as radio interfaces (e.g., WiFi) or GPU.
Software related to Hardware
Firmware is low-level software that is embedded directly into hardware devices, typically stored in non-volatile memory such as ROM or flash memory.
You can read more about firmware on this post.
Scale Integration
Scale integration:
- SSI
- MSI
- LSI
- VLSI
- ULSI
Small SI (SSI) has 10 components.
Medium SI (MSI) has 100 components.
Large SI (LSI)
Very Large Scale Integration (VLSI)
Ultra Large Scale Integration ()
Computer Generations
Computer generations:
- 1st generation
- 2st Generation
- 3rd Generation
- 4th Generation
- 5th Generation
Precedent
Charles Babbage theorized about a functional computer and Ada Lovelace programmed for it.
1st Generation (1940-1955)
Characteristics:
- Vacuum tubes
- Relay
- Programmed directly machine language
Examples: ENIAC, EDVAC.
Von Neumann formulated the Von Neumann architecture.
2nd Generation (1955-1968)
Characteristics:
- Transistors
- Assemblers
- Early high-level languages (COBOL, FORTRAN)
- SSI and MSI
Examples: Univac, IBM, Borroughts E-101
3rd Generation (1969-1977)
Characteristics:
- Semiconductors
- Integrated circuits
- Microprocessors like Intel 4004 (1971) and Intel 8008 (1972)
- New high-level languages PASCAL, BASIC
- LSI, early VLSI
Example: IBM S/360, ILLIAC IV, Cray (vectorial processors)
4th Generation (1977-1984)
Characteristics:
- Personal computers, like Apple I (1976), Apple II (1977), IBM PC (1981), Apple Macintosh (1984).
- Processors 8086 and 8088
- VLSI
5th Generation (1985-nowadays)
Characteristics:
- ULSI
- RISC
- Multiprocessors, multicore
- Distributed systems
- Internet