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Lecture 18 - March 14, 2003
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AGENDA:
0 Admin
1 P5 questions?
2 Ch 3.7: disks in MINIX
3 Quiz #4

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0 - ADMIN
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Startout Q: 

Due Monday: 
* P5

Local friendly Dungeon programming contest this
  Saturday (March 15). 1-3:30pm or so. You don't need
  a full team to participate. We can match you up
  when you arrive.

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1 - P5 QUESTIONS?
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Questions?

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2 - CH 3.7: DISKS IN MINIX
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The problems of legacy assumptions: 6-bit sector
  counter. BIOS, lies, and other horrible stories.

Disk software
* what goes into calculating total time?

  seek + rotational delay + actual transfer time

* disk arm scheduling algorithms - any thoughts

  - FCFS (aka FIFO), SSF, elevator algorithms,
    C-scan

Error handling - what sorts of errors and how handle?

* programming, transient checksum probs., permanent
  checksum probs., seek error, controller error

* Bad block - how would you deal with one
  - bad block file
  - alternatives to bad block file

Track caching
* how would you go about it

MINIX hard disk driver
* How deal with multiple controllers?
* Role of BIOS
* detecting devices at startup
* why initialize devices only when first access them?

Implementing HD driver

* so what do we need to worry about?

Implementing floppy driver

* so what do we need to worry about?


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3 - QUIZ #4
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Take quiz (10 minutes)
COS 421 - Lecture Notes #18		SPRING 2003	
COS421-lect-2003-03-14.doc	Page 1	Printed 17.03.03