What Hardware Temporarily Stores Information When Software is Being Used?
When software is being run, what temporary storage hardware stores information so it can be accessed by the CPU? The answer is RAM (random access memory).
Typically, a computer’s central processing unit pulls data from RAM, processes it, and writes it back to RAM millions of times per second.
Random Access Memory (RAM)
What hardware temporarily stores information when software is running?
Random Access Memory (RAM) is the temporary storage component of a computer and it’s where data is stored while loading websites, typing documents, or jumping in and out of video games. Because RAM enables fast access to needed information when needed, you can do more work on your machine without having to move it away to a hard drive.
RAM chips store information as electric charges are applied to capacitors and transistors. Each cell’s charge is unique, allowing the processor to differentiate between values representing 1 or 0. Since capacitors lose energy over time, DRAM must periodically replenish itself with an electronic charge to compensate for leakage.
Dynamic random access memory (DRAM) is the primary type of RAM found in most computers. DRAM chips require constant power to maintain data and must be refreshed every few milliseconds to compensate for leaks in capacitors.
Static random access memory (SRAM) does not need to be refreshed as often, but it still requires constant power to keep its data. SRAM chips are commonly found in CPU cache memory as they can be accessed faster and require less power consumption.
DRAM works by storing each bit of information in a single capacitor, with transistors controlling how much charge is applied to that capacitor. Once turned off, however, this discharges the capacitor and no longer serves to store data; only by turning it on again can this same capacitor be used again for storage purposes.
Because a transistor can only turn on when it is certain the capacitor contains information, it is necessary to monitor the amount of charge in each cell. To do this, an electronic signal varying the resistance of a transistor helps determine whether or not there is any charge present in each capacitor.
RAM microchips were initially asynchronous, meaning their clock speed differed from that of the computer’s processor. Synchronous dynamic RAM (SDRAM) was developed around the 1990s to help RAM keep up with processor demands for data. This double-data-rate SDRAM moves data twice during each clock cycle – at its beginning and ending addresses.
Read Only Memory (ROM)
When booting up your computer, it will first turn on its power supply and perform a POST (power-on self-test). This ensures all components are functioning properly. To obtain essential information for proper operation, this information will be sent to a read-only memory chip (ROM), which then executes software instructions.
ROM storage is nonvolatile, meaning it retains its data even after power has been turned off. This makes ROM ideal for storing important information like the Basic Input/Output System (BIOS) and firmware for hardware devices that must remain intact.
RAM has m output lines and n input lines, each assigned a unique address value. These input lines are connected to logic gates that determine which word should be selected and applied to the output lines at any given time; for instance, if the input address is 000001, word number 1 would be selected and applied since binary 000001 equals 1 in decimal form.
There are various types of RAM. These include MROM, PROM, and Mask ROM.
MROM (Managed Read Only Memory) is a type of Random Access Memory (ROM) that has been programmed during manufacture. This type of ROM is inexpensive and already contains preprogrammed data or instructions.
PROM is a type of RAM that can be programmed by users but does not come pre-programmed. Instead, manufacturers leave it blank to enable programming by the user. PROMs are commonly found in video game consoles, mobile phones, and microcontrollers.
ROM is often employed in embedded systems, where it enables application development and testing without needing to install hard disks or connect them to a computer. This type of technology can also be found in home appliances and consumer electronics (MP3 players, set-top boxes) as a reliable, cost-effective alternative to static RAM. Alternatively, ROM could be replaced by reprogrammable nonvolatile memory technologies like UV-EPROM or EEPROM which support erase-rewrite cycles.
I/O Ports
Ports are types of interfaces that enable computers to attach to peripherals like keyboards, mice, and printers. Ports may also be connected to modems or network interfaces.
Input devices provide computer instructions or input data, such as a keyboard, mouse, or microphone. Output devices display the results of these instructions or data output — like a monitor, printer, or speaker.
Typically, I/O devices are managed by an I/O subsystem on a separate chip or processor. Its primary responsibility is to handle routine signaling and provide working data to the CPU. Though integral parts of a microcontroller’s hardware design, its management must be overseen by the operating system for everything to function optimally.
As you can see, a port’s primary responsibility is enabling software to communicate with the outside world. To do this, the I/O subsystem utilizes various functions (see Figure 6.7), which vary depending on the architecture and chipset used.
The inb_p function is one of the most popular, performing a small bit of hardware caching that speeds up CPU access to its registers. Unfortunately, this optimization may not work with all memory-mapped I/O regions and could alter what a write to a memory-mapped region means.
Furthermore, this function may cause the hardware to reorder writes to its registers in an unreadable fashion. Reordering might be necessary for certain situations to reduce redundancy or improve efficiency.
This function is commonly employed for single-byte I/O operations; however, its performance benefits cannot be realized when performing more than one byte per transfer. This limitation is especially prevalent when the device doesn’t support any sort of asynchronous I/O, such as with many USB adapters. Pausing functions provide a solution in such cases by pausing software while hardware performs I/O operations so it can read or write data quickly.
System Bus
What hardware temporarily stores information when software is running?
All hardware has a system bus, which is an interconnecting network of wires connecting its various components. This bus transmits data between the CPU and memory, between the CPU and peripheral devices, as well as between various parts of a computer.
Computer buses operate according to a schedule, “picking up” and “dropping off” data at regular intervals. This ensures efficient retrieval and writing of data.
The bus is classified according to how many bits it can transfer simultaneously, such as 8-bit, 16-bit, 32-bit, or even 64-bit. The width of a bus refers to how many wires can simultaneously carry bits between the CPU and memory and determines the speed of data flow between these two elements.
Therefore, a faster bus is beneficial for the CPU and main memory, since it can transfer data more quickly. The faster a bus transfers data, the smoother your computer’s operation will run.
Computer buses also carry memory addresses, which enable the CPU to refer to locations in memory. When reading or writing from that location, the CPU sends its address on the bus for reference.
When the CPU sends a memory read or write command on the control bus to access data in the main memory, it also includes its address on the address bus. This ensures that it knows where to locate that location for accurate execution of the operation.
When the CPU sends an interrupt signal on the control bus to interrupt processing, it also sends along with it the address of a memory location on the address bus. In this way, other components in a computer can synchronize their activity by waiting for instructions from the CPU before proceeding with any operations. Oftentimes, acknowledgment signals or other timing information is transmitted over this same control bus so other parts know to wait for instructions from the CPU before completing their work.
