Computer Architecture Essays - Computer Memory, Digital Electronics

Computer Architecture Computer Architecture 1. There have been a lot of developments in microprocessors since the 286 chip. The 286 CPU are no longer sold and are very rarely found in commercial use today because of its running speed, which is between 10MHz to 20MHz. This processor has a 24-bit address bus, and is able to address up to 16 million different address locations. It also has two operating modes, which are real mode and protected mode. The real mode is basically for normal DOS operations and it uses only 8086 code (8086 was the previous CPU). When it was in protected mode the CPU is able to access beyond the 1mb address limit and employed its added features, which were intended for multi-tasking operations such as Windows, but this CPU is not powerful enough to carry out these multi-tasking operations. The 286 came with a bus width of 16-bit internal, 24-bit address, and 16-bit external, with an external speed of between 6MHz 25MHz, and an internal speed of between 6MHz 25MHz. The next CPU was the 386, this is also no longer produced it had a slightly faster running speeds which are between 16MHz to 40MHz. This CPU could carry out effective multi tasking operations. It also had a substantial improvement in both memory management and it had an enlarged instruction set. It is also the minimum CPU for running windows. It came in two types the 386 SX and the 386 DX. The SX had a 32-bit internal data path but it only had a 16-bit path between the CPU and the computer memory. The DX on the other hand had a 32-bit data bus between the CPU and the memory chips allowing larger data transfers so it had faster through put. It also was able to use external cache memory, usually about 64k, which also improved performance. The 386 came in two different types they both had a internal bus width of 32 bit, the SX had a address bus width of 24 bit, and a external bus width of 16 bit, its internal and external speed was between 16MHz 33MHz. The DX however had an address and external bus width of 32 bit, its internal and external speed was between 33MHz40MHz. The 486 were the next CPU, this is still produced, there was little change to the 386 instruction set, but the 486 ran at speeds between 20MHz to 100MHz. There was more emphasis placed on the enhancements to improve the performance. It was also available in the DX and SX varieties. The difference between them was that the DX had a maths co-processor the SX did not, the Motherboards that used the 486SX chip had a spare maths co-processor socket to upgrade to a DX. The 486 chip because of its design to carry out the most common instructions in a single clock cycle this was a faster than the previous CPUs. It also had 8k of bit in cache memory, the new burst mode it had, allowed memory transfers from consecutive memory locations to be carried out at one clock cycle. The 486 came in four different types they all had a bus width of 32 bit (internal, address, and external), with an external speed of between 20MHz 50MHz. The differences between them were in the internal speeds of the CPU. The SX had an internal speed of between 20MHz 50MHz, the DX had an internal speed of between 25MHz 50MHz, the DX2 had an internal speed of between 50MHz 66MHz. The DX4 had an internal speed of between 100MHz 120MHz, which was actually faster than the bottom of the Pentium range. The Pentium CPU came and is the current entry level standard for computers. This CPU is effectively two that are in the one chip. This then allows two instructions to be executed in parallel, which means it greatly speeds up throughput. It also has the main mathematical operations hard wired into the chip this then means that it can be up to ten times faster than the 486DX maths coprocessor can. All the Pentium models are supercalar. The basic chip has two integer processing pipelines. It also