Historically, computers used several different architectures to decide how much memory they accessed in each memory word. These memory words of different lengths can vary from the software development process to the day-to-day use of the computer. How different architectures affect the memory capacity of a computer.
First, we'll look at the historical context of the evolution of computer architecture. Next, we'll look at some of the general characteristics of computers that use 32-bit and 64-bit architectures. So, we'll look at how much memory can be addressed with 32-bit and 64-bit architectures.
Most electronic computer machines require memory to perform their tasks. Historically, the need for memory has changed as computing power has evolved. Traditional computers employ processors, such as 8 or 16 bits in the computer registers for one-time access.
However, modern computers often require more memory to execute programs. It led to the rise of 32-bit architectures, which were very popular in the 90s and early 2000s.
As technology evolves, more memory is needed to represent data and instructions. As a result, the adoption of 64-bit computers has been growing from the late 2000s to the present. It's important to emphasize that while 64-bit computers have replaced 32-bit computers, 32-bit computers are still being used heavily.
We can understand 32-bit and 64-bit architectures as the amount of data processed by the CPU at a time. For example, the architecture defines the total memory that a register can support at one time. In addition, it usually determines the size of the instruction set used by the processor.
However, the additional memory for processing instructions and data in the registers is only a point. A 64-bit architecture can handle more memory than a 32-bit architecture, such as random memory and virtual memory. We will see a detailed explanation of this in the next section.
In addition, the program has a version according to the processor architecture. However, in general, this does not mean modifying the source of the program.
In this way, changing from one architecture to another often means defining some of the compiler's configuration flags. So, the biggest difference is in the program's binary.
Finally, 64-bit processors also have compatibility advantages. Typically, 64-bit processors can run both 64-bit and 32-bit versions of the operating system. In turn, a 32-bit processor cannot run a 64-bit operating system.
One of the most significant differences between adopting a 32-bit or 64-bit architecture is the amount of memory addressed. As we previously noted in the previous section, a 64-bit architecture can handle more memory than a 32-bit architecture.
In terms of random access memory, the 32-bit architecture addresses up to 4GB of memory. In turn, the theoretical limit of a 64-bit architecture is to address 16 million TB of memory.
This difference in memory support comes from the number of different addresses that can be represented in a single memory word. We should keep in mind that a computer is byte by byte exactly mapping its memory.