CS 457/557 Assignment 1, Disks

Due Friday 19 January 2018

1. Moore's Law Exercises, p. 514, updated(?), or p. 561, 2nd edition

  Exercise 11.2.1 describes the "typical computer in 2001"  as 1.5GHz processor, 100 Mb main memory and 40 Gb disk.
(and in 2nd ed.) the "typical computer in 2008"  as 2 processors of 3GHz , 1 Gb main memory and 250 Gb disk.
Moore's law says that these numbers double every 18 months
  1. How closely do these 2 computers follow Moore's Law?
  2. What is the "typical" PC today (2018)? Look at some current ads.
  3. What will the typical computer be like in 2021? ( based on your answer #2.)
Notes:
I bought my first computer, a low-end PC, in June 1987 (for $1600). It had a 7MHz processor, 640 Kb main memory, and a 20 Mb disk.
Processor speeds seem to have reached a thermodynamic limit, instead more "cores" are being included in processors.
2. Exercises, p. 567, a) - e), g) [Graduate students do all]: (The numbers were smaller in the 1st edition, except for mechanical ones (disks can physically only spin so fast.)

Statistics for the "Megatron 777" disk:

  1. 10 surfaces, 100,000 tracks each
  2. Tracks average 1000 sectors of 1024 bytes
  3. Tracks average about 2 inches in diameter, so let's say 6.4 circumference
  4. 20% of each track used for gaps
  5. 10,000 rpm
  6. Head moves n tracks in 1 + 0.0002n milliseconds.
Calculate
(a) capacity,
(b) density of bits in the sectors of a track,
(c) maximum seek time,
(d) maximum rotational latency ,
(e) 4Kb block transfer time,
(f) [Graduate students] What is the average seek time?
(g) average rotational latency

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