A 64-bit processor refers to a microprocessor that can process data and instructions in chunks of 64 bits. Microprocessors that can handle 64 bits perform a larger number of calculations per second compared to 32-bit processors. Typical variations of the term include 64-bit CPU, 64-bit computing and 64-bit microprocessor.
Every microprocessor handles two key criteria: memory addresses and the corresponding data or instruction present at each memory address. Thus, microprocessors are tied to memory where applications and data are executed, and the number of bits available on a processor define the memory size and space, as well as the volume of data that a processor can handle per unit of time. This has become a de facto way of classifying or categorizing modern processors.
A 64-bit processor uses internal registers -- temporary storage locations within the processor -- that are 64 bits wide. This typically corresponds to an address bus and data bus that are also 64 bits wide. The address bus is the pathway of electrical signals used to determine the device or memory address that the processor is attempting to access. The data bus is the pathway used to exchange data with the intended address. Processors also include signaling for a third control bus, but this bus is typically a unique collection of discrete, or individual, digital signals and does not operate like an address or data bus.
64-bit processors may include and support the following advanced technologies:
However, these features are generally not a direct result of 64-bit registers or address or data bus design. For our purposes, the principle distinction between 32-bit and 64-bit processors is the increased bus width.
The simple notation of 64-bit may sound unimpressive by itself, but the use of 64 bits brings powerful implications for computers. In binary parlance, 264, or two raised to the 64th power, equates to 18,446,744,073,709,551,616 unique numbers. For an address bus, that is about 18 exabytes of potential addressable memory space. For a data bus, that is 18 quintillion different possible values. It is leaps and bounds more than the 4 gigabytes of addressable memory space possible with previous 32-bit processors (232 = 4,294,967,296).
Considering the large investment involved in computer hardware and software, the idea of backward compatibility is critical -- will what I have now work on something different or new? Moving from a 32-bit to a 64-bit architecture could potentially be disruptive. Even though 64-bit computing has been the norm for well over a decade now, it is worth considering the implications of such a transition.
Hardware. 64-bit processors are not compatible with 32-bit processors. The sheer number of signal pins involved in the processor's packaging is enough to ensure that a 64-bit processor cannot simply drop into a 32-bit processor socket on the computer's motherboard. At a minimum, a 64-bit computer requires an entire motherboard replacement to support the 64-bit processor, differing clock and bus configurations, new chipsets to interface the processor to other input/output devices like disks and ports, and sockets for much larger memory devices.
Most system diagnostics reveal the current processor hardware configuration. For example, Microsoft Windows 10 shows basic system details by selecting Settings > About.
OSes. 64-bit processors have taken great pains to support compatibility between both 32-bit OSes and 64-bit OSes. A computer owner who licensed a 32-bit OS should be able to reinstall or use that OS on a 64-bit computer. However, the advanced features, functionality and performance of the 64-bit processor may not be available without a suitable 64-bit OS. Emerging OSes, such as Windows 11, dropped support for 32-bit architectures and no longer support 32-bit computing.
Software drivers. Drivers are small bits of software designed to extend the capabilities and compatibilities of an OS by enabling it to recognize, configure and use hardware devices. The drivers should match the OS. So, a 32-bit OS should run with 32-bit drivers, and a 64-bit OS should use corresponding 64-bit drivers. A 32-bit driver is not compatible with a 64-bit OS. Most hardware devices have both 32-bit and 64-bit driver versions available, so select the driver version that is appropriate for the OS.
If a 64-bit driver is not available for a hardware device, it may be possible to use a generic 64-bit driver, although some of the device's specialized or proprietary features may be unavailable. Otherwise, the device needs to be replaced with a new device that does include a suitable driver.
Applications. Most 32-bit applications function on a 64-bit processor and 64-bit OS. The only applications that do not operate properly on a 64-bit platform are those that rely specifically on 32-bit drivers -- which are not compatible with 64-bit OSes -- or those applications that incorporate 32-bit processor-specific instructions or code. Today, only the most unique or niche applications continue to use 32-bit environments, and almost all enterprise applications have updates and patches available to handle 64-bit software versions.
64-bit processors offer numerous advantages, including the following:
Still, there are several drawbacks to today's 64-bit processors, including the following:
The terms CPU and microprocessor are used interchangeably, and while they both execute some of the same computer tasks, their functions differ slightly. Learn how CPUs and microprocessors differ.
09 Mar 2022