Different computers used different block sizes and IBM notably used variable block sizes but the popularity of the IBM PC caused the industry to adopt a standard of 512 user data bytes per block by the middle 1980s.
12.
A Extended Count Key Data ( ECKD ); however the use of variable block size in HDDs fell out of use in the 1990s; one of the last HDDs to support variable block size was the IBM 3390 Model 9, announced May 1993.
13.
A Extended Count Key Data ( ECKD ); however the use of variable block size in HDDs fell out of use in the 1990s; one of the last HDDs to support variable block size was the IBM 3390 Model 9, announced May 1993.
14.
Three common descriptions of " palpitation " are " flip-flopping " ( or " stop and start " ), often caused by premature contraction of the atrium or ventricle, with the perceived " stop " from the pause following the contraction, and the " start " from the subsequent forceful contraction; rapid " fluttering in the chest, " with regular " fluttering " suggesting supraventricular or ventricular arrhythmias ( including sinus tachycardia ) and irregular " fluttering " suggesting atrial fibrillation, atrial flutter, or tachycardia with variable block; and " pounding in the neck " or neck pulsations, often due to " cannon " A waves in the jugular venous pulsations that occur when the right atrium contracts against a closed tricuspid valve.
