Making sense of MFM, RLL, SCSI and ESDI

Users interested in high-end microcomputers should become familiar with the ever-flowing river of acronyms in order to keep abreast of technological developments. Both the original modified frequency modulation (MFM) and the newer run length limited (RLL) data coding sequences are compatible with the IBM ST-506 hard disk system (HDS), for instance. Both MFM and RLL became obsolete with the advent of the small computer systems interface (SCSI) and enhanced small device interface (ESDI). Other terms, such as seek time, explain the various measures of hard disk performance.