The processor is the most important part of your computer. If you don’t have one, you won’t even have a computer. Processor size is the number of bits the processor can interpret and execute at a given time. For example, a 16-bit processor can interpret and execute 16 bits at a time. A 32-bit processor can interpret and execute 32 bits at a time, and so on. To examine how processor size affects system performance, let’s take a look at the Intel 80486 and 80386 processors. These two processors have different processor sizes. The 80486 has an 8-bit processor that can interpret and execute 8 bits at a time. The 80386 has a 6-bit processor that can interpret and execute 6 bits at a time. So what does this mean?
The smaller the processor, the more difficult it is for the processor to interpret information from on-chip memory, thereby slowing down overall system performance. (The main memory component in your computer that determines the speed of your computer.
1. Bigger is Better
Being based on the 286, true processor speed is not an issue for the 386. The big problem for the 386 is apparent when you look at the number of instructions it can execute in a single clock cycle. The 8086 could execute one instruction per clock cycle, and so could the 286. However, the 386 can only handle one-half instruction per clock cycle – that means that the 386 just executes instructions twice as fast as the 286.
Some new instructions have been added to the newer chip (386) to compensate for this problem; however, these instructions will only work on new programs developed specifically to utilize them. Very few programs developed today will utilize the 386’s new instructions, so it’s not likely that they will see a significant processor speed up.
2. The Big Thing Is Smaller
The 80486 is a 16-bit chip with a 16-bit address bus. With such a large address bus, it could issue the same amount of instructions as the 80386; however, it takes more than twice as many clock cycles to do this. The 20-bit bus on the 80386 allows it to issue more instructions per clock cycle than the 16-bit chip (486).
The 386 has also added some new instructions, so it has some of the same capabilities as a programmable coprocessor – yet another speed up. It is also introducing a new cache technology that will allow the 80386 to execute instructions faster than ever before. The 80386 will be twice as fast as the fastest 386 available today, and four times faster than anyone’s 286.
3. The Closer the Better
The 386 is a 16-bit chip with a 20-bit address bus and a 32-bit internal data bus. These facts alone allow it to do so much more than its predecessor, the 286. However, Intel decided to go even further by making it compatible with its 8-bit chip (the 80186). This allows the 80386 to operate as an 80286 while using almost half of the power. This also allows the 386 to run 286 software faster than anyone else’s 286 – even though there are no new instructions in that software.
4. The Farther the Better
By making the 386 use so much less power than its predecessor, Intel can also keep it operating at a higher speed for longer periods of time. Intel is able to do this by switching to a faster oscillator. The 80286 used an 8-MHz oscillator, whereas the 386 uses a 20-MHz oscillator. This seems like quite a jump, but it’s not that risky. The 80286 was designed from the ground up to run as fast as possible – it had no other function. The 386 was designed to handle more complex tasks and still have time left over for fun stuff. Since the 386 is designed for multiple functions, it does not need to run at the fastest speed available – just fast enough to handle its function.
5. The Quicker the Better
The 80286 took about two years to develop, whereas the 80386 was created in only a year and a half. A big reason for this was that much of the work on the 386 was already done by the time they started designing it. If you use what you already have and add quality improvements over time, your product should be better than your competitors’ new products almost every time. This also means that there is less of a chance for bugs to be inserted into your product.
6. The Larger the Better (Usually)
The 80486 can hold up to 8M bytes of memory in its lion’s head, whereas the 486 can only hold up to 4M. The 80386 has a 32-bit address bus that is twice as large as the 486’s 16-bit address bus. This makes it capable of addressing 16M bytes. This sounds like more memory than you’ll ever need, but by the time you add in all the system software, driver software and such that you’ll need, there won’t be much space left in your new computer for anything else – until there comes along a 386 with 64-bit access.
7. The Slower the Better (Usually)
The 486 ran at about 1.4MHz, whereas the 386 can run as fast as 3.2GHz. The 80286 ran at 2MHz, and in comparison with the 486, the 386 runs almost twice as fast – even though both are 16-bit processors.