Understanding Computer Hardware: A Deep Dive into Storage, Memory, and the CPU - Prof. Mar, Papers of School management&administration

Download Understanding Computer Hardware: A Deep Dive into Storage, Memory, and the CPU - Prof. Mar and more Papers School management&administration in PDF only on Docsity! 1/21 PÏi?ÑÍÎÌËÊÉ Grad School of Lib & Info Sci., Univ. of Illinois http://www.lis.uiuc.edu/ Hardware Overview LIS 315 * Spring 2004 Introduction to Networked Systems http://www.isrl.uiuc.edu/˜mwolske/lis315/spring04 Martin Wolske mwolske@uiuc.edu 2/21 PÏi?ÑÍÎÌËÊÉ After the Keystrokes • What happens in a computer after a series of keystrokes (and mouse clicks) prompt Word to open a document? – A clock pulse acts as a drill sergent defining when any action can take place – Paper must be moved from storage to memory, passing through the OS on the CPU on the way – Program reads paper from memory to determine characteristics of document – Program uses CPU to calculate how mcuh can be displayed and instructs OS what to display – OS instructs CPU to work with video controller to update display 5/21 PÏi?ÑÍÎÌËÊÉ After the Keystrokes Interacting with Memory • Memory stores information in chunks rather than whole papers • When memory is full, something must be written to storage to make room. This is one reason having more memory can improve the speed that a computer operates – anything that can be done to avoid waiting for storage is good. • Memory requires 3-7 clock cycles to perform the steps to retrieve data from a quadrant of memory (newer types of memory use various tricks to speed this process up). We’ll talk about this more next week. 6/21 PÏi?ÑÍÎÌËÊÉ After the Keystrokes Comparing Storage and Memory • The differences in medium provide differing strengths and weaknesses. • What are the strengths and weaknesses of storage? Memory? • What are some steps you can think of to improve the performance of storage? Mem- ory? • While both storage and memory have each changed over time to improve overall performance, neither has been able to keep pace with the performance of other com- ponents, like the CPU 7/21 PÏi?ÑÍÎÌËÊÉ After the Keystrokes The CPU • Both applications and the operating system depend on the the CPU to execute all of their instructions • Over time the performance of the CPU has incremented well beyond that of other components – The speed of the CPU has increased, allowing it to perform many times faster than any other part of the computer. Modern CPU’s run at many times the speed of the rest of the computer. – As the number of transistors have increased within the Integrated Circuit that is the CPU, more functions have been added to the CPU, including the capacity to handle multiple sets of instructions at once, the ability to store bits of information directly in the CPU, and more complex instruction sets that allow programs to interact more efficiently with the CPU. 10/21 PÏi?ÑÍÎÌËÊÉ Moving Data Around – The Busses More on the ISA bus • The ISA bus was one of the earliest standards for moving around data. It can only transfer data at 8- or 16-bits at one time. • The ISA bus is not very condusive to plug and play technology, meaning add-in cards need varying levels of manual configuration. • While it’s limitations may suggest it shoiuld never be used, it’s only been in the last few years that the cost of PCI devices have been less expensive ISA devices. As a result, there’s still a lot of used ISA-based equipment to be found. 11/21 PÏi?ÑÍÎÌËÊÉ Moving Data Around – The Busses More on the PCI bus • The Peripheral Component Interconnect (PCI) bus is today’s standard for adding peripherals inside the computer. • The PCI bus transfers 32-bits of data at one time, and operates at 33 or 66 MHz. How do these numbers compare with the ISA bus and why is this of value? • The PCI bus works much better in supporting plug and play devices, and is much more effective in using limited computer resources. 12/21 PÏi?ÑÍÎÌËÊÉ Moving Data Around – The Busses Adding devices outside the box • Two expansion ports used extensively in older computers to connect devices outside the box include the serial and parallel ports. However, these are relatively slow, they work with only one device at a time, and are not plug and play compatible. • One older bus standard still extensively used in high end computers to provide higher speed connections for external devices is the Small Computer System Interface (SCSI, pronounced scuzzy) • A new implementation of SCSI finding wide acceptance is formally known as IEEE 1394. Apple, realizing this was not a very user friendly name, has dubbed this firewire. • Another new and inexpensive bus that is commonly availabe in computers today is the Universal Serial Bus (USB). • Both firewire and USB support many devices simultaneously and support plug and play. Firewire and USB are beginning to replace the need to add devices internally altogether. 15/21 PÏi?ÑÍÎÌËÊÉ BIOS and CMOS • BIOS, or Basic Input Output System, is a program that provides information on what the computer can and can’t do. This program, unlike other programs, is stored on Read Only Memory (ROM) and is available to the computer without the computer knowing anything else (e.g., what hard drives are installed in the computer) • CMOS is a type of memory that can be rewritten but that requires very little power to maintain the information. It stores setup information for the computer and is accessed by BIOS for current settings. 16/21 PÏi?ÑÍÎÌËÊÉ Finding the Boot Device • For a computer to be functional for users, it needs to load an operating system. The boot device is the place where the operating system is stored when power is removed from the computer. • CMOS is used to specify where to look for a boot device. Often, this can be a series of devices which are probed in order (e.g., first look to the A: floppy drive, then the CD-Rom, then the hard drive). 17/21 PÏi?ÑÍÎÌËÊÉ Accessing CMOS • Access to the setup screen stored in CMOS is useful not only to make configura- tion changes, but to understand what is currently recognized by the computer as an available resource. As such it is a useful tool for inventorying and diagnostics. • Access to CMOS varies across systems: – Pressing a specified key during bootup (e.g., <Delete>, <F10>) – Pressing a specified key sequence after booting (e.g., <CTRL><ALT><ENTER>, <CTRL><ALT><S>) – Using a boot floppy or running a program from the hard drive