1. Processing data: Introduction to Processors CHAPTER 4 Factors affecting Processing speed 1. width of Registers: Register is a type of high speed memory unit built onto the CPU used for calculations. A 32 bit processor indicate the width of the register or the word length that can be handled by the processor. Register does arithmetic, logical and moving operations. E.G. Register A hold content of 7 and B holds content of 3: operation: compare Whether A>B. if A>B true then divide A by B. so register C calculates A/B=7/3=2.33. the result is stored in register D. the moved to RAM. If not saved the hard disk the data is lost RAM as RAM is volatile.

2. Factors affecting Processing speed 2. No of registers: having many registers facilitate greater speed. e.g. PowerMac G5 has 80 register vs. Pentium 4 has 16 registers. 3. RAM size: having a larger RAM/ memory increases processing power. Upgrading a RAM is one of the cheapest and most effective way of improving CPU performance. Having a larger RAM reduces virtual memory thus improving performance

3. Factors affecting Processing speed 4. Reducing virtual memory: What is Virtual memory: When you open a program or application. You don’t need to access all the contents of the program at once. You only need a partial amount of features of the program. Vast majority of the application is actually unused. Unused content of the RAM is returned to the hard disk which is called virtual memory. Essentially swapping data from RAM to hard disk forms Virtual memory. Too much swapping reduces performance. Because too much capacity wasted on moving data than actual read/write

4. Increasing RAM reduces virtual memory If you have a 1 GB RAM. You want to open a 500 MB application.150 MB is swapped in from the hard disk to the RAM on startup. So 350 MB is returned to the hard disk. So 350 MB is the virtual memory in this RAM. Increased virtual memory will reduce performance If you have a 2 GB RAM. You want to open a 500 MB application. 300 MB is swapped in from the hard disk to the RAM on startup. So 200 MB is returned to the hard disk. So 200 MB is the virtual memory in this RAM Reduced virtual memory will increase performance

5. Factors affecting Processing speed 5. Increasing internal clock: The internal clock of a processor defines the speed of the processor. If we have a 3.3 GHz processor that means the clock of the processor process 3.3 billion cycles per second. Clock is made of a quartz crystal whose materail is silica(SiO2- silicon di oxide). same material that is sand made of. Piezo-Electric effect: if you apply electricity to the crystal. The crystal will vibrate at a fixed frequency.

6. Factors affecting Processing speed The CPU ticks at 3.3 billion times per second just as our watch ticks at 1 second interval. It also indicates the transistors in the processor will switch ON/OFF 3.3 billion times every second. It also means each cycle of the clock takes 1/3.3 billion second. 1 cycle of the clock=0.3 nanosecond.

7. Factors affecting Processing speed 6. Width of BUS: Bus is the parallel wires that connect different parts of the CPU: Bus is like the highway system that connects different cities. So if we have wider highways e.g. 8 lane highway will transport more cars than 4 or 2 lane highway. So a 32 bit bus will process twice the among data than a 16 bit processor, everything else held constant.

8. Factors affecting Processing speed

9. 7. Clock frequency of bus: If a processor has bus of 3.2 GHz whereas the data bus has 800 MHz then there will be a delay or lag. Processor and data bus clock frequencies are equally important. 8. Having larger cache memory: operating principle of cache memory: When CPU needs to read a data, it first checks whether it is already stored in cache memory before swapping it in from RAM, if it is already not there then CPU reads the data from RAM to registers, at the same time leaves a copy in the cache. So next time if CPU needs the data it can find it in cache memory.

10. Cache memory as different parts of computer has different speed. If you sort from higher to lower speed then Processor is faster than Cache Processor>Cache>RAM>Hard disk drive>CD- ROM player>Floppy disk Drive So to cope with extremely fast processor, a fast speed cache memory is installed in between processor and RAM.

11. Cache memory Cache memory is made of static RAM whereas usual RAM is made of Dynamic RAM. DRAM packs one bit per transistor but SRAM packs only one bit for 3 or 4 transistors. That’s why SRAM is faster because it is dense but more expensive also smaller than DRAM. DRAM or RAM is slower than cache memory or SRAM. But RAM is larger than cache memory also less expensive than RAM in terms of cost per bit.

12. Cache memory cont. 3 types of cache 1. Level 1( L1): built onto CPU, holds recently run data. 2. Level 2(L2): holds potential upcoming data. Intel, AMD found that if L2 cache is built onto CPU it greatly increases performance. Level 3(L3): holds possible data. built on motherboard found only on server and workstations.

14. Factors affecting Processing speed

18. Various bus standards 1. ISA(Industry Standard Architecture)-16 bit bus developed by IBM used on IBM PC/XT. ATA bus renamed to be used on IBM PC/AT running Intel 80286 processor. Backward-compatible with 8-bit systems. 32 bit version was not popular. Gang of 9- 9 competing PC clone manufacturers developed Extended ISA. 2. Local Bus: it is a bus that connects CPU with external devices directly.

19. 3. PCI(Peripheral Component Interface)- a 32-bit 33 MHz local bus standard developed by Intel though not tied to any processor. It has a clock speed of 33 MHz to run at 32 bit. It can run 64 bit at 66 MHz. Motherboards employ ISA for slower devices and PCI for faster devices. In 1993 Intel and Microsoft designed Plug-and-Play ISA(called ISA PnP) so that any device driver can be installed automatically. Later PCI express was developed to connect high speed devices mostly broadband internet connection such as Gigabit Ethernet, also USB 2.0 devices.

20. 4.AGP-Accelerated Graphics Port)- 32 bit 2.1 GHz bus to connect high speed graphics card and video card made by graphic chip divisions of Intel, AMD, Nvidia, ATI(Array Technology Inc.Canada, later acquired by AMD. 5. USB(Universal Serial Bus)-480 MHz, 32 bit and hot swappable to connect newer devices. Best feature 127 daisy chain connected devices.

21. Daisy chain devices

22. 5. Firewire (Apple’s version of IEEE 1394 but incresingly used on PC): 400 MHz 32 bit hot swappable bus to connect high data speed devices such as video camera, digital TV. In 2011 Apple started to replace Firewire with Thunderbolt. Firewire allows peer to data communication e.g. sanner to printer data transfer. It has 80% capacity for Iso-synchronous(fixed data)and 20 % capacity for asynchronous(variable data). That’s why it is popular in aircraft data communications, also used in Internet connection over FireWire, digital camera, Digital Video Recorders, cable TV boxes, iPod and iPhone 3GS charging dropped in favor of USB. NB: AGP, USB 2.0, FireWire faster bus due to high clock speed of 2.1 GHz, 480 and 400 MHz

23. 7. PC CardBus: 32 bit, 33 MHz same as PCI bus only difference hot swappable, size of Credit card. Used for NIC(network Interface Card), Modems, Wi-Fi cards, usually used for notebook/laptops. Mostly No longer used due to popularity of USB bus. 3 types of PC card Type I: flash, RAM, Cache storage and memory devices Type II: Networking Type III: Small 2.5” inch Hard disk drives instead of the regular 3.5” inch HDD. Type III is thicker than Type II and Type II is thicker than Type I CompactFlash flash memory device is a smaller version of PC Card.