Memory.pdf, Study notes of Logic

Download Memory.pdf and more Study notes Logic in PDF only on Docsity! Tele 2060 " Main Memory o Fast Access o Directly Accessable by CPU o Usually RAM or ROM " Secondary Storage o Access Via 1/O Subsystem o Normally Disk Storage Memory and Storage Martin B.H. Weiss Memory andStorage - 1 University of Pittsburgh Tele 2060 " An Array of "Registers" " Each "Register" is a Memory Location b7 b6 bs ba b3 b2 bi bo Structure of Memory 17 Register N (Location N) Register N-1 (Location N-1) Register N-2 (Location N-2) Register 1 (Location 1) Register 0 (Location 0) Martin B.H. Weiss Memory and Storage - 2 University of Pittsburgh Tele 2060 Data is Organized in Words Structure of Memory o Contains the Maximum Number of Bits the CPU Can Utilize v Larger Words Imply the Ability to Deal with Larger Numbers u Smaller CPU's Must Make Multiple Fetches to Memory o Processors Are Classified According to Word Size Words Are Stored in Memory Locations Memory Locations Have an Address o This is Equivalent to the Register Number o Also, The Location Martin B.IL Weiss Memory and Storage - 3 University of Pittsburgb 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 o Data Are Stored in Small Capacitors o Must Be Refreshed Periodically Static RAM's o Data Are Stored in Flip Flop's o No Refresh Is Necessary Non-Volatile RAM's o Do Not Lose Their Contents After Power is Turned Off o May Be Dynamic or Static RAM's Martin B.H. Weiss Memory and Storage - 4 University of Pittsburgh Sequential Access Memory Data Must Be Accessed in a Sequence With Other Data Direct Access o The Computer Can Directly Access the Storage Medium o Occurs Via a Transducer o Via the I/O Subsystem o DASD is the IBM Acronym for Disk Storage Indirect Access o Tape Subsystem o Intermediate System Is Required Martin B.H . Weiss Tele 2060 Read-Only Memory " Memory Contents Are Fixed (Permanently Programmed) o Permanent Changes Are Often Made at a Device Level o Burning A Silicon Fuse o Causing Physical Material Changes By High Voltage " Programmable Read-Only Memory (PROM) " Erasable Programmable ROM (EPROM) " Electrically Alterable ROM (EPROM) Martin B.H. Weiss Memory and Storage - 9 Tele 2060 University ofPittsburgh Memory and Storage-10 University of Pittsburgh Tele 2060 Constant Angular Velocity (CAV) o Rotational Speed Remains Constant o Data Density Varies o High Near Spindle o Low Near Perimeter o Applications v Most Hard Disks a Many Flexible Disks Constant Linear Velocity (CLV) o Rotational Speed Varies o Data Density Is Constant o Some Flexible Disks o CD/ROMs Disk Types Martin B.H. Weiss Memory and Storage - 12 University of Pittsburgh Tele 2060 Programmable Logic Device Allows the development of inexpensive "custom" chip functions Types of PLDs o PROM o Form of Memory Device o Program the Truth Table of a Function o Programmable Logic Array (PLA) o Standard Chip o Based on Minterm Structure of Boolean Expressions o Inputs Connected by Fuses to AND/OR gates o PAL o Similar to PLAs o Easier to Program than aPLA Martin B.1L Weiss Memory and' Storage -13 University of Pittsburgh Tele 2060 Structure of PLAs Martin B.H. Weiss Memory and Storage - 14 University of Pittsburgh W.01 =Mml D- I ~a~- nnrnnnmn O O F1 F2 MENEM Cy O O F3 F4