from Stan Paddock, 10/26/2009

I know I am going to start another round of discussion with the enclosed subject, so I thought I would capture the facts first. If you have any questions, let me know.

Overview

Transfer Rates
Sheet1


Sheet 1: Transfer Rates



Sheet 2: Sheet1

Magnetic Tape







No. of units that can be connected




6 Units

No. of chars/linear inch of tape




556 Char/inch

Channels or tracks on the tape




7 Tracks/tape

Blank tape separating each record




0.75 Inches

Tape speed




75 Inches/sec

Transfer rate




15,000 to 62,500 Char/sec

Start time




7.3 or 10.8 Millisec

Stop time




7.3 or 10.8 Millisec

Average time for experienced







operator to change reel of tape




60 - 120 Seconds

Physical properties of tape







Width




0.5 Inches

Length of reel




2,400 Feet

Composition




Mylar

Two tape units can be specified:




729 II or 729 IV.










Records Record Length Blocking Factor Total Data Record Time Transfer rate


1000 80 1 80,000 12.0 6,667


1000 160 2 160,000 14.5 11,034


1000 320 4 320,000 19.5 16,410


1000 640 8 640,000 26.5 24,151


1000 1280 16 1,280,000 43.0 29,767


1000 2560 32 2,560,000 73.0 35,068











100% transfer rate 75 ips * 556 bpi =



41,700











Records Record Length Blocking Factor Record Length IN Record Time Records Time Per Cent Transfer Capstaan Time
1000 80 1 0.14 0 1.92 15.99% 10.08 ms
1000 160 2 0.29 0 3.84 26.46% 10.66 ms
1000 320 4 0.58 0.01 7.67 39.35% 11.83 ms
1000 640 8 1.15 0.02 15.35 57.92% 11.15 ms
1000 1280 16 2.3 0.03 30.70 71.38% 12.3 ms
1000 2560 32 4.6 0.06 61.39 84.10% 11.61 ms
















11272.78 ms