Memory and Storage, Exercises of Logic

Download Memory and Storage and more Exercises Logic in PDF only on Docsity! Memory and Storage - 1 Martin B.H. Weiss University of Pittsburgh Tele 2060 Memory and Storage • Main Memory  Fast Access  Directly Accessable by CPU  Usually RAM or ROM • Secondary Storage  Access Via I/O Subsystem  Normally Disk Storage Memory and Storage - 2 Martin B.H. Weiss University of Pittsburgh Tele 2060 Structure of Memory b7 b6 b5 b4 b3 b2 b1 b0 Register N (Location N) Register N-1 (Location N-1) Register N-2 (Location N-2) Register 1 (Location 1) Register 0 (Location 0) • An Array of “Registers” • Each “Register” is a Memory Location Memory and Storage - 3 Martin B.H. Weiss University of Pittsburgh Tele 2060 Structure of Memory • Data is Organized in Words  Contains the Maximum Number of Bits the CPU Can Utilize ‰ Larger Words Imply the Ability to Deal with Larger Numbers ‰ Smaller CPU's Must Make Multiple Fetches to Memory  Processors Are Classified According to Word Size • Words Are Stored in Memory Locations • Memory Locations Have an Address  This is Equivalent to the Register Number  Also, The Location Memory and Storage - 4 Martin B.H. Weiss University of Pittsburgh Tele 2060 Random-Access Memory (Read-Write) • Memory Locations Can be Accessed in Any Order (i.e., Randomly) • An Address is Decoded into a Memory Location By a n-to-2n Decoder • Dynamic RAM's  Data Are Stored in Small Capacitors  Must Be Refreshed Periodically • Static RAM's  Data Are Stored in Flip Flop's  No Refresh Is Necessary • Non-Volatile RAM's  Do Not Lose Their Contents After Power is Turned Off  May Be Dynamic or Static RAM's Memory and Storage - 9 Martin B.H. Weiss University of Pittsburgh Tele 2060 Read-Only Memory • Memory Contents Are Fixed (Permanently Programmed)  Permanent Changes Are Often Made at a Device Level  Burning A Silicon Fuse  Causing Physical Material Changes By High Voltage • Programmable Read-Only Memory (PROM) • Erasable Programmable ROM (EPROM) • Electrically Alterable ROM (EAROM) Memory and Storage - 10 Martin B.H. Weiss University of Pittsburgh Tele 2060 Sequential Access Memory • Data Must Be Accessed in a Sequence With Other Data • Direct Access  The Computer Can Directly Access the Storage Medium  Occurs Via a Transducer  Via the I/O Subsystem  DASD is the IBM Acronym for Disk Storage • Indirect Access  Tape Subsystem  Intermediate System Is Required Memory and Storage - 11 Martin B.H. Weiss University of Pittsburgh Tele 2060 Structure of Disk Drives Sector Tracks Read/ Write Head Arm Memory and Storage - 12 Martin B.H. Weiss University of Pittsburgh Tele 2060 Disk Types • Constant Angular Velocity (CAV)  Rotational Speed Remains Constant  Data Density Varies ‰ High Near Spindle ‰ Low Near Perimeter  Applications ‰ Most Hard Disks ‰ Many Flexible Disks • Constant Linear Velocity (CLV)  Rotational Speed Varies  Data Density Is Constant ‰ Some Flexible Disks ‰ CD/ROMs Memory and Storage - 13 Martin B.H. Weiss University of Pittsburgh Tele 2060 Programmable Logic Device • Allows the development of inexpensive “custom” chip functions • Types of PLDs  PROM ‰ Form of Memory Device ‰ Program the Truth Table of a Function  Programmable Logic Array (PLA) ‰ Standard Chip ‰ Based on Minterm Structure of Boolean Expressions ‰ Inputs Connected by Fuses to AND/OR gates  PAL ‰ Similar to PLAs ‰ Easier to Program than a PLA Memory and Storage - 14 Martin B.H. Weiss University of Pittsburgh Tele 2060 Structure of PLAs A B C 1 0 F1 F2 F3 F4