How to determine if a processor is 8-bit; 16-bit or 32-bit

Question

Whether the address bus size is determined; if so, was the 8086 20-bit processor? If there are no criteria for assigning a bit number, such as an 8-bit, 16-bit, 32-bit processor?

Answer 1

Undefined. In general, as xtofl points out, this is the size of an atomic unit of calculation (on early computers, this was not always synonymous with "register"). Thus, the PDP-10 was a 36-bit machine, the 8080 was 8 bits, and the IBM 360 or Intel 80386 was “32 bits”.

But there are exceptions. Motorola 68000 and 68010 processors implemented a 32-bit set of registers, but they did it with microcode on top of the 16-bit internal architecture. At that time, they were usually sold as "16-bit" processors.

The size of the address bus is almost never a determining factor. All successful 8-bit CPUs have implemented, for example, 16-bit addressing (often using odd hacks to compensate for the lack of a single address register, indirect addressing modes 6502 or H / L Z80 registers). And 8086, as you mentioned, used its register of segment registers to get 20 address lines for operation (80286 extended this trick to 24 bits of the physical address). And in the other direction, many “32-bit” CPUs had smaller address buses to save logic that would not be used on a machine that would never have more than a few megabytes of memory: 68000 is limited to addressing up to 24 bits, although the pointers themselves were 32. Similarly, modern 64-bit CPUs universally implement less than 64 bits of a physical address.

Answer 2

I assume that you usually label it with the size of your batteries / registers.

Answer 3

As for the processor, I would say that this is the width of the register. You can only perform an operation of 8 bits , 16-bit , 32-bit , etc. at a time.

Answer 4

As far as I know, the processor bit width is determined by the number of bits that immediately accept internal data processing circuits. For example, if adders, multipliers, etc. The ALU accepts 16-bit operands, then the processor is 16 bits, and if it accepts 32 bits, then it is 32 bits. It does not matter what the width of the data bus or address bus is. In general, the Accumulator bit length determines the processor bit length.

Answer 5

The bit size (8 bits, 16 bits, 32 bits) of the microprocessor is determined by the hardware, in particular the data bus width. Intel 8086 is a 16-bit processor because it can move 16 bits per data bus. The Intel 8088 is an 8-bit processor, although it has an identical instruction set. This is similar to the Motorola 68000 and 68008 processors. The bit size is not determined by the programmer's representation (register width and address range).

Answer 6

I think the first number of Integrated chip refers to the type of processor. If it is an IC 8085, it is an 8-bit processor.

Answer 7

any processor can be indicated by its two attributes

• instruction set architecture &
• not. a bit that it can process in a single clock cycle.

take, for example, the Intel IA-32 architecture, also called x86-32, here x86 indicates the architecture and 32 indicates a 32-bit processor

X architecture

there are several architectures

Pre-x86 x86

- IA-32 Integrated Architecture, also called x86-32 -x86-64 - with AMD AMD64 and Intel Intel 64 versions of this - Motorola 6800 and 68000 a

rchitectures ARM7

Y-bit processor

: simple - its processor / processor data processing capacity per cycle. Suppose this is an 8-bit processor, then in one clock cycle, the ALU can only work with 8-bit data (note that this operation can be an internal operation, such as add / sub, as well as transferring data to another input device -output)

classification Based on Registers- 

In addition to ALU and CU, the processor also contains some memory cells called register. depending on the processor, a register can usually store 8, 16, 32, or 64 bits. The register size of a particular processor allows us to classify the processor. Processors with an n-bit register size are called n-bit processors, so processors with 8-bit registers are called 8-bit processors.

 classification Based on databus width- 

since alu can only process 8-bit data per cycle, it does not make sense that the data bus width is larger and the 8-bit processor has an 8-bit data bus, so bus width can also be an alternative way to find out the processing capabilities of the processor bits. For a processor with an n bit data bus, the processor can transfer n-bits to another device in one operation.

for the question:

"suppose we have a 32-bit ALU, that is, it can take 32 bits at a time and our data bus is 16 bits in size, that is, it can store 16 bits of data at a time tht wht will be ans. In this case ...? "

An example of such a processor would be the Intel 8088 and Moto 68000.

Using the bus width classification, the Intel 8088 microprocessor is an 8-bit processor since it uses an 8-bit data bus, although its processor registers are actually 16-bit registers. Similarly, the Motorola 68000 is classified as a 16-bit processor, although its processor registers are 32-bit registers. Sometimes a combination of the two classifications is used where the 8088 can be called an 8/16-bit processor and the Motorola 68000 as a 16/32-bit processor.

Answer 8

The word size (8 bits, 16 bits or 32 bits) of a microprocessor is the size of the data path in the execution module. This is usually the size of the battery. This is the size of the executive unit. An example of this is the 8088, which is a 16-bit computer running on an 8-bit bus. 8085 - 8 bits. 8086/8088 - 16 bits. 80386 - 32 bits. Intel Mordern 64-bit processors.