ITEC 1000 Lecture Notes - Direct-Access Storage Device, Hard Disk Drive, Disk Pack
Document Summary
Itec 1000 winter 2010 peter khaiter. Lecture 9/10 computer peripherals mar 8/15. Devices that are external to the main processing function of the computer: not the cpu, memory, power supply. Parallel, usb, serial: interface to systems bus. Access time: the technology or product type that holds the data, the time to locate data and read it, specified as an average in seconds (e. g. , s, ms, s, ns, etc. ) Throughput/transfer rate: amount of data (in consecutive bytes) moved per second, specified in bytes/s (e. g. , kbytes/s, mbytes/s) Direct access storage device (dasd: pronounced dazz-dee , term coined by ibm, distinguishes disks (disk head moves directly to the data) from tapes (tape reel must wind forward or backward to the data: sequential access) Primary memory (cache, conventional memory) immediate access by cpu. Expanded storage (e. g. , ram) a buffer between conventional memory and secondary memory)